Vitamins - as found in nature or kitchen Vitamin A

[MommaDogs]

I thought it would be a very good discussion here to talk about different aspects of nutrition.

 

There may come a time when Coden Alimentarius takes away our rights, or production lines of vitamins shut down, or the local health food store no longer exists, etc. I have begun to prepare by planting trees or locating trees and herbs known to provide these substances.

 

A few I have in mind are:

--How to make nutrients more bioavailable (cooking, fermenting, combining with fats, etc)

--How to find nutrients in nature if they are unavailable at the store (mulberries, pine needles, kidney fat, etc for Vit C - etc)

--How to get medicines from glandulars and organs (esp for thyroid patients, heart patients, etc)

--Maybe even lists of the best sources of each vitamin/nutrient

--Discussion of antinutrients

 

I'll present scientific evidence for each argument when available. Most medical journals are online and the www.searchedu.com function works very well for this.

 

Let's go in order, I'll start with Vitamin A later today. Anyone out there with knowledge that wants to jump in?

[Darlene]

This is a critically needed, and brilliant idea. Thank you so much for spearheading it.

 

((((MD)))))

[CrabGrassAcres]

Sweet potatoes! Any leafy greens. That means planting collards for winter in the south. Livermush for breakfast. LOL

[Homemaker]

Red palm oil has lots of A, but you'd need to be in the tropics.

Egg yolks and grass fed butter. Cod liver oil if you live way, way up north to get it locally.

 

By the way... plan on healthy fats in your diet to help you convert the beta carotene in the vegetable sources into vitamin A.

[gramma lois]

Vitamin A: (Retinol)

 

Vitamin A deficiency is common throughout the world in underdeveloped, overpopulated countries. Vitamin A deficiency is a major cause of blindness and death in children in these countries. Vitamin A is present in two forms. In food of animal origin it is found as the active vitamin (retinol), while in plant foods it is found as provitamin A carotenes, a precursor of vitamin A.

 

Carotene is an orange-yellow pigment that is present in green vegetables, bus is masked by the green color of the chlorophyl in the leaves. A precursor, or provitamin, is a substance that is changed in the body to a vitamin. Only a portion of the carotene that we eat is changed to vitamin A. This takes place in the wall of the small intestine. The amount that is changed varies between 30 and 70 percent, depending on the type of food and the form in which it is eaten. Carotene itself is not active in the body.

 

In most of the food we eat about half of the vitamin A is in the form of retinol, and the other falf is provitamin A. The liver stores about 90 - 95 percent of our vitamin A, enought to last months or perhaps even years under normal circumstances.

 

Functions:

 

Gives ability to see in dim light

Maintains normal skin

Needed for growth and development of strong bones and teeth

Needed for the secretion of mucus by the cells lining the respiratory, urinary, and intestinal tracts that helps keep them moist and health

Aids in the normal reproductive processes

Needed for carbohydrate metabolism in the liver

Essential for proper smell, hearing and taste

Aids in the prevention of certain types of cancer

Beta carotene is a non-toxic antioxidant and helps prevent disease by neutralizing fee radicals

 

 

Deficiency:

 

Poor vision in dim light (night blindness)

Dry, scaly, itchy skin

Increased susceptibility to infections, specially in the respiratory tract

Changes in the eyes that may lead to blindness. The eyes cecome dry, swollen, and infected.

Slow wound healing

Poor bone growth in children

Defective enamel on teeth and an increased number of cavities

Loss of taste and smell

Stunting of body growth

 

Toxicity:

 

Because vitamin A cannot be excreted from the body in any significant ammount, prolonged daily doses in excess of 50,000 IU in adults and less in children will have toxic results. Toxicity only occurs with retinol and not with carotene. An excess intake of carotene will cause the skin to turn yellow

 

 

Stability

 

Very little vitamin A is lost during cooking or processing. it is stable to heat and alkali, but not when it is exposed to acids, light, or oxygen.

 

 

Source: Back to Eden by Jethro Kloss

 

 

 

 

 

Some plants from which the body manufactures vitamin A are:

 

Dandelion greens, lambsquarter, carrots, yellow dock, turnip greens, sweet potatoes, pokeweed (young shoots), spearmint, parsley, blue violet, chard, kale, collards, mustard greens, spinach, chickory greens, watercress, brocoli, elderberries, winter cress, papaya, cantelope, alfalfa, cranberry, bilberries, artichokes, brier hips, buckwheat, calendula, cowslip (flowers), elencampane (flowers), garlic, iceland moss, Indian corn, lettuce, lily of the valley, okra, red currants, saffron, rowan (fruit), apricots

 

Source: The Herb Book by John Lust

[MommaDogs]

Thanks, everyone. I got a great response by PM also, so I guess this is a good enough idea.

 

Gramma Lois, thank you for doing that. I wanted to put a summary at the start of each vitamin, so that works well.

 

Here's what I know in summary form about Vitamin A.

Gramma Lois already put in what it's good for - eyesight being one of the first issues you'll notice if you're deficient.

 

Many studies have been done on Vitamin A in pregnancy, with warnings never to take it, but those studies were all done on the chemical compound made in a lab, not in natural Retinol as found in liver and animal products.

 

It is true as Homemaker says - that if you want to make Vitamin A from plant sources, you will need fat to convert it. However, even then, conversion is poor at best. Animal sources remain the best way to obtain vitamin A.

 

My source of vitamin A is liver and HIGH VITAMIN cod liver oil (I use Green Pastures) - regular CLO that you buy in the store has been heated, deodorized and cleaned to remove all vitamins and then synthetically a bit of them are added back in. True cod liver oil will have a ratio of 10:1 Vitamin A to Vitamin D.

 

I'm going to post three posts in full, and I'll do a summary of each if someone tells me they can't / don't have time to read through them all. These are all excellent sources, so I had a hard time cutting them down - and in the case of the Weston Price articles, I didn't have permission to cut anything out, so they are here as they appear.

 

 

[MommaDogs]

Couldn't figure out the tables, sorry... hope you can understand them

 

From our illustrious government:

http://dietary-supplements.info.nih.gov/fa...ts/vitamina.asp

Dietary Supplement Fact Sheet: Vitamin A and Carotenoids Office of Dietary Supplements • National Institutes of Health

 

 

 

 

Vitamin A: What is it?

Vitamin A is a group of compounds that play an important role in vision, bone growth, reproduction, cell division, and cell differentiation (in which a cell becomes part of the brain, muscle, lungs, blood, or other specialized tissue.) [1-5]. Vitamin A helps regulate the immune system, which helps prevent or fight off infections by making white blood cells that destroy harmful bacteria and viruses [1,6-10]. Vitamin A also may help lymphocytes (a type of white blood cell) fight infections more effectively.

 

Vitamin A promotes healthy surface linings of the eyes and the respiratory, urinary, and intestinal tracts [8]. When those linings break down, it becomes easier for bacteria to enter the body and cause infection. Vitamin A also helps the skin and mucous membranes function as a barrier to bacteria and viruses [9-11].

 

In general, there are two categories of vitamin A, depending on whether the food source is an animal or a plant.

 

Vitamin A found in foods that come from animals is called preformed vitamin A. It is absorbed in the form of retinol, one of the most usable (active) forms of vitamin A. Sources include liver, whole milk, and some fortified food products. Retinol can be made into retinal and retinoic acid (other active forms of vitamin A) in the body [1].

 

Vitamin A that is found in colorful fruits and vegetables is called provitamin A carotenoid. They can be made into retinol in the body. In the United States, approximately 26% of vitamin A consumed by men and 34% of vitamin A consumed by women is in the form of provitamin A carotenoids [1]. Common provitamin A carotenoids found in foods that come from plants are beta-carotene, alpha-carotene, and beta-cryptoxanthin [11]. Among these, beta-carotene is most efficiently made into retinol [1,13-15]. Alpha-carotene and beta-cryptoxanthin are also converted to vitamin A, but only half as efficiently as beta-carotene [1].

 

Of the 563 identified carotenoids, fewer than 10% can be made into vitamin A in the body [12]. Lycopene, lutein, and zeaxanthin are carotenoids that do not have vitamin A activity but have other health promoting properties [1]. The Institute of Medicine (IOM) encourages consumption of all carotenoid-rich fruits and vegetables for their health-promoting benefits.

 

Some provitamin A carotenoids have been shown to function as antioxidants in laboratory studies; however, this role has not been consistently demonstrated in humans [1]. Antioxidants protect cells from free radicals, which are potentially damaging by-products of oxygen metabolism that may contribute to the development of some chronic diseases [3,14-15].

What foods provide vitamin A?

Retinol is found in foods that come from animals such as whole eggs, milk, and liver. Most fat-free milk and dried nonfat milk solids sold in the United States are fortified with vitamin A to replace the amount lost when the fat is removed [16]. Fortified foods such as fortified breakfast cereals also provide vitamin A. Provitamin A carotenoids are abundant in darkly colored fruits and vegetables. The 2000 National Health and Nutrition Examination Survey (NHANES) indicated that major dietary contributors of retinol are milk, margarine, eggs, beef liver and fortified breakfast cereals, whereas major contributors of provitamin A carotenoids are carrots, cantaloupes, sweet potatoes, and spinach [17].

 

Vitamin A in foods that come from animals is well absorbed and used efficiently by the body. Vitamin A in foods that come from plants is not as well absorbed as animal sources of vitamin A. Tables 1 and 2 suggest many sources of vitamin A and provitamin A carotenoids [18].

 

Table 1: Selected animal sources of vitamin A [18]

Food Vitamin A (IU)* %DV**

Liver, beef, cooked, 3 ounces 27,185 545

Liver, chicken, cooked, 3 ounces 12,325 245

Milk, fortified skim, 1 cup 500 10

Cheese, cheddar, 1 ounce 284 6

Milk, whole (3.25% fat), 1 cup 249 5

Egg substitute, ¼ cup 226 5

 

 

Table 2: Selected plant sources of vitamin A (from beta-carotene) [18]

Food Vitamin A (IU)* %DV**

Carrot juice, canned, ½ cup 22,567 450

Carrots, boiled, ½ cup slices 13,418 270

Spinach, frozen, boiled, ½ cup 11,458 230

Kale, frozen, boiled, ½ cup 9,558 190

Carrots, 1 raw (7½ inches) 8,666 175

Vegetable soup, canned, chunky, ready-to-serve, 1 cup 5,820 115

Cantaloupe, 1 cup cubes 5,411 110

Spinach, raw, 1 cup 2,813 55

Apricots with skin, juice pack, ½ cup 2,063 40

Apricot nectar, canned, ½ cup 1,651 35

Papaya, 1 cup cubes 1,532 30

Mango, 1 cup sliced 1,262 25

Oatmeal, instant, fortified, plain, prepared with water, 1 cup 1,252 25

Peas, frozen, boiled, ½ cup 1,050 20

Tomato juice, canned, 6 ounces 819 15

Peaches, canned, juice pack, ½ cup halves or slices 473 10

Peach, 1 medium 319 6

Pepper, sweet, red, raw, 1 ring (3 inches diameter by ¼ inch thick) 313 6

 

* IU = International Units

** DV = Daily Value. DVs are reference numbers based on the Recommended Dietary Allowances (RDAs). They were developed to help consumers determine if a food contains a lot or a little of a nutrient. The DV for vitamin A is 5,000 IU. Most food labels do not list vitamin A content. The percent DV (%DV) column in the table above indicates the percentage of the DV provided in one serving. A food providing 5% or less of the DV is a low source while a food that provides 10% to 19% of the DV is a good source. A food that provides 20% or more of the DV is high in that nutrient. It is important to remember that foods that provide lower percentages of the DV also contribute to a healthful diet. For foods not listed in this table, refer to the U.S. Department of Agriculture's Nutrient Database Web site: http://www.nal.usda.gov/fnic/cgi-bin/nut_search.pl.

What are recommended intakes of vitamin A?

Recommendations for vitamin A are provided in the Dietary Reference Intakes (DRIs) developed by the Institute of Medicine (IOM) [1]. DRI is the general term for a set of reference values used for planning and assessing nutrient intake in healthy people. Three important types of reference values included in the DRIs are Recommended Dietary Allowances (RDA), Adequate Intakes (AI), and Tolerable Upper Intake Levels (UL). The RDA recommends the average daily dietary intake level that is sufficient to meet the nutrient requirements of nearly all (97% to 98%) healthy individuals in each age and gender group [1]. An AI is set when there are insufficient scientific data to establish an RDA. AIs meet or exceed the amount needed to maintain nutritional adequacy in nearly all people. The UL, on the other hand, is the maximum daily intake unlikely to result in adverse health effects [1].

 

In Table 3, RDAs for vitamin A are listed as micrograms (mcg) of Retinol Activity Equivalents (RAE) to account for the different biological activities of retinol and provitamin A carotenoids [1]. Table 3 also lists RDAs for vitamin A in International Units (IU), which are used on food and supplement labels (1 RAE = 3.3 IU).

 

Table 3: Recommended Dietary Allowances (RDAs) for vitamin A

Age

(years) Children

(mcg RAE) Males

(mcg RAE) Females

(mcg RAE) Pregnancy

(mcg RAE) Lactation

(mcg RAE)

1-3 300

(1,000 IU)

4-8 400

(1,320 IU)

9-13 600

(2,000 IU)

14-18 900

(3,000 IU) 700

(2,310 IU) 750

(2,500 IU) 1,200

(4,000 IU)

19+ 900

(3,000 IU) 700

(2,310 IU) 770

(2,565 IU) 1,300

(4,300 IU)

 

Information is insufficient to establish an RDA for vitamin A for infants. AIs have been established based on the amount of vitamin A consumed by healthy infants fed breast milk (Table 4) [1].

 

Table 4: Adequate Intakes (AIs) for vitamin A for infants

Age (months) Males and females (mcg RAE)

0-6 400 (1,320 IU)

7-12 500 (1,650 IU)

 

The NHANES III survey (1988-1994) found that most Americans consume recommended amounts of vitamin A [19]. More recent NHANES data (1999-2000) show average adult intakes to be about 3,300 IU per day, which also suggests that most Americans get enough vitamin A [20].

 

There is no RDA for beta-carotene or other provitamin A carotenoids. The IOM states that consuming 3 mg to 6 mg of beta-carotene daily (equivalent to 833 IU to 1,667 IU vitamin A) will maintain blood levels of beta-carotene in the range associated with a lower risk of chronic diseases [1]. A diet that provides five or more servings of fruits and vegetables per day and includes some dark green and leafy vegetables and deep yellow or orange fruits should provide sufficient beta-carotene and other carotenoids.

When can vitamin A deficiency occur?

Vitamin A deficiency is common in developing countries but rarely seen in the United States. Approximately 250,000 to 500,000 malnourished children in the developing world become blind each year from a deficiency of vitamin A [1]. In the United States, vitamin A deficiency is most often associated with strict dietary restrictions and excess alcohol intake [21]. Severe zinc deficiency, which is also associated with strict dietary limitations, often accompanies vitamin A deficiency. Zinc is required to make retinol binding protein (RBP) which transports vitamin A. Therefore, a deficiency in zinc limits the body's ability to move vitamin A stores from the liver to body tissues [1].

 

Night blindness is one of the first signs of vitamin A deficiency. In ancient Egypt, it was known that night blindness could be cured by eating liver, which was later found to be a rich source of the vitamin [2]. Vitamin A deficiency contributes to blindness by making the cornea very dry and damaging the retina and cornea [22].

 

Vitamin A deficiency diminishes the ability to fight infections. In countries where such deficiency is common and immunization programs are limited, millions of children die each year from complications of infectious diseases such as measles [23]. In vitamin A-deficient individuals, cells lining the lungs lose their ability to remove disease-causing microorganisms. This may contribute to the pneumonia associated with vitamin A deficiency [2,6-7].

 

There is increased interest in early forms of vitamin A deficiency, described as low storage levels of vitamin A that do not cause obvious deficiency symptoms. This mild degree of vitamin A deficiency may increase children's risk of developing respiratory and diarrheal infections, decrease growth rate, slow bone development, and decrease likelihood of survival from serious illness [24-25]. Children in the United States who are considered to be at increased risk for subclinical vitamin A deficiency include:

• toddlers and preschool age children;

• children living at or below the poverty level;

• children with inadequate health care or immunizations;

• children living in areas with known nutritional deficiencies;

• recent immigrants or refugees from developing countries with high incidence of vitamin A deficiency or measles; and

• children with diseases of the pancreas, liver, or intestines, or with inadequate fat digestion or absorption.

A deficiency can occur when vitamin A is lost through chronic diarrhea and through an overall inadequate intake, as is often seen with protein-energy malnutrition. Low blood retinol concentrations indicate depleted levels of vitamin A. This occurs with vitamin A deficiency but also can result from an inadequate intake of protein, calories, and zinc, since these nutrients are needed to make RBP [1]. Iron deficiency can also affect vitamin A metabolism, and iron supplements provided to iron-deficient individuals may improve body stores of vitamin A and iron [1].

 

Excess alcohol intake depletes vitamin A stores. Also, diets high in alcohol often do not provide recommended amounts of vitamin A [1]. It is very important for people who consume excessive amounts of alcohol to include good sources of vitamin A in their diets. Vitamin A supplements may not be recommended for individuals who abuse alcohol, however, because their livers may be more susceptible to potential toxicity from high doses of vitamin A [26]. A medical doctor will need to evaluate this situation and determine the need for vitamin A supplements.

Who may need extra vitamin A to prevent a deficiency?

Vitamin A deficiency rarely occurs in the United States, but the World Health Organization (WHO) and the United Nations Children's Fund (UNICEF) recommend vitamin A administration for all children diagnosed with measles in communities where vitamin A deficiency is a serious problem and where death from measles is greater than 1%. In 1994, the American Academy of Pediatrics recommended vitamin A supplements for two subgroups of children likely to be at high risk for subclinical vitamin A deficiency: children aged 6 months to 24 months who are hospitalized with measles, and hospitalized children older than 6 months [27].

 

Fat malabsorption can result in diarrhea and prevent normal absorption of vitamin A. Over time this may result in vitamin A deficiency. Those conditions include:

• Celiac disease:

Often referred to as sprue, celiac disease is a genetic disorder. People with celiac disease become sick when they eat a protein called gluten found in wheat and some other grains. In celiac disease, gluten can trigger damage to the small intestine, where most nutrient absorption occurs. Approximately 30% to 60% of people with celiac disease have gastrointestinal-motility disorders such as diarrhea [28].They must follow a gluten-free diet to avoid malabsorption and other symptoms.

• Crohn's disease:

This inflammatory bowel disease affects the small intestine. People with Crohn's disease often experience diarrhea, fat malabsorption, and malnutrition [29].

• Pancreatic disorders:

Because the pancreas secretes enzymes that are important for fat absorption, pancreatic disorders often result in fat malabsorption [30-31]. Without these enzymes, it is difficult to absorb fat. Many people with pancreatic disease take pancreatic enzymes in pill form to prevent fat malabsorption and diarrhea.

Healthy adults usually have a reserve of vitamin A stored in their livers and should not be at risk of deficiency during periods of temporary or short-term fat malabsorption. Long-term problems absorbing fat, however, may result in deficiency. In these instances physicians may recommend additional vitamin A [9].

 

Vegetarians who do not consume eggs and dairy foods need provitamin A carotenoids to meet their need for vitamin A [1]. They should include a minimum of five servings of fruits and vegetables in their daily diet and regularly choose dark green leafy vegetables and orange and yellow fruits to consume recommended amounts of vitamin A.

What are some current issues and controversies about vitamin A?

Vitamin A, beta carotene, and cancer

Dietary intake studies suggest an association between diets rich in beta-carotene and vitamin A and a lower risk of many types of cancer [32]. A higher intake of green and yellow vegetables or other food sources of beta carotene and/or vitamin A may decrease the risk of lung cancer [2,33-34]. However, a number of studies that tested the role of beta-carotene supplements in cancer prevention did not find them to protect against the disease. In the Alpha-Tocopherol Beta-Carotene (ATBC) Cancer Prevention Study, more than 29,000 men who regularly smoked cigarettes were randomized to receive 20 mg beta-carotene alone, 50 mg alpha-tocopherol alone, supplements of both, or a placebo for 5 to 8 years. Incidence of lung cancer was 18% higher among men who took the beta-carotene supplement. Eight percent more men in this group died, as compared to those receiving other treatments or placebo [35]. Similar results were seen in the Carotene and Retinol Efficacy Trial (CARET), a lung cancer chemoprevention study that provided subjects with supplements of 30 mg beta-carotene and 25,000 IU retinyl palmitate (a form of vitamin A) or a placebo. This study was stopped after researchers discovered that subjects receiving beta-carotene had a 46% higher risk of dying from lung cancer [36-37].

 

The IOM states that "beta-carotene supplements are not advisable for the general population," although they also state that this advice "does not pertain to the possible use of supplemental beta-carotene as a provitamin A source for the prevention of vitamin A deficiency in populations with inadequate vitamin A" [1].

 

Vitamin A and osteoporosis

Osteoporosis, a disorder characterized by porous and weak bones, is a serious health problem for more than 10 million Americans, 80% of whom are women. Another 18 million Americans have decreased bone density which precedes the development of osteoporosis. Many factors increase the risk for developing osteoporosis, including being female, thin, inactive, at advanced age, and having a family history of osteoporosis. An inadequate dietary intake of calcium, cigarette smoking, and excessive intake of alcohol also increase the risk [38-40].

 

Researchers are now examining a potential new risk factor for osteoporosis: an excess intake of vitamin A. Animal, human, and laboratory research suggests an association between greater vitamin A intake and weaker bones [40-41]. Worldwide, the highest incidence of osteoporosis occurs in northern Europe, a population with a high intake of vitamin A [42]. However, decreased biosynthesis of vitamin D associated with lower levels of sun exposure in this population may also contribute to this finding.

 

One small study of nine healthy individuals in Sweden found that the amount of vitamin A in one serving of liver may impair the ability of vitamin D to promote calcium absorption [43]. To further test the association between excess dietary intakes of vitamin A and increased risk for hip fractures, researchers in Sweden compared bone mineral density and retinol intake in approximately 250 women with a first hip fracture to 875 age-matched controls. They found that a dietary retinol intake greater than 1,500 mcg/day (more than twice the recommended intake for women) was associated with reduced bone mineral density and increased risk of hip fracture as compared to women who consumed less than 500 mcg/day [44].

 

This issue was also examined by researchers with the Nurses Health Study, who looked at the association between vitamin A intake and hip fractures in over 72,000 postmenopausal women. Women who consumed the most vitamin A in foods and supplements (3,000 mcg or more per day as retinol equivalents, which is over three times the recommended intake) had a significantly increased risk of experiencing a hip fracture as compared to those consuming the least amount (less than 1,250 mcg/day). The effect was lessened by use of estrogens. These observations raise questions about the effect of retinol because retinol intakes greater than 2,000 mcg/day were associated with an increased risk of hip fracture as compared to intakes less than 500 mcg [45].

 

A longitudinal study in more than 2,000 Swedish men compared blood levels of retinol to the incidence of fractures in men. The investigators found that the risk of fractures was greatest in men with the highest blood levels of retinol (more than 75 mcg per deciliter [dL]). Men with blood retinol levels in the 99th percentile (greater than 103 mcg per dL) had an overall risk of fracture that exceeded the risk among men with lower levels of retinol by a factor of seven [46]. High vitamin A intake, however, does not necessarily equate to high blood levels of retinol. Age, gender, hormones, and genetics also influence these levels. Researchers did not find any association between blood levels of beta-carotene and risk of hip fracture. Researchers' findings, which are consistent with the results of animal, in vitro (laboratory), and epidemiologic studies, suggest that intakes above the UL, or approximately two times that of the RDA for vitamin A, may pose subtle risks to bone health that require further study.

 

The Centers for Disease Control and Prevention (CDC) reviewed data from NHANES III (1988-94) to determine whether there was any association between bone mineral density and blood levels of retinyl esters, a form of vitamin A [47]. No significant associations between blood levels of retinyl esters and bone mineral density in 5,800 subjects were found.

 

There is no evidence of an association between beta-carotene intake, especially from fruits and vegetables, and increased risk of osteoporosis. Current evidence points to a possible association with vitamin A as retinol only. If you have specific questions regarding your intake of vitamin A and risk of osteoporosis, discuss this information with your physician or other qualified healthcare provider to determine what's best for your personal health.

What are the health risks of too much vitamin A?

Hypervitaminosis A refers to high storage levels of vitamin A in the body that can lead to toxic symptoms. There are four major adverse effects of hypervitaminosis A: birth defects, liver abnormalities, reduced bone mineral density that may result in osteoporosis (see the previous section), and central nervous system disorders [1,48-49].

 

Toxic symptoms can also arise after consuming very large amounts of preformed vitamin A over a short period of time. Signs of acute toxicity include nausea and vomiting, headache, dizziness, blurred vision, and muscular uncoordination [1,48-49]. Although hypervitaminosis A can occur when large amounts of liver are regularly consumed, most cases result from taking excess amounts of the nutrient in supplements.

 

The IOM has established Tolerable Upper Intake Levels (ULs) for vitamin A that apply to healthy populations [1]. The UL was established to help prevent the risk of vitamin A toxicity. The risk of adverse health effects increases at intakes greater than the UL. The UL does not apply to malnourished individuals receiving vitamin A either periodically or through fortification programs as a means of preventing vitamin A deficiency. It also does not apply to individuals being treated with vitamin A by medical doctors for diseases such as retinitis pigmentosa.

 

Table 5: Tolerable Upper Intake Levels (ULs) for retinol

Age

(years) Children

(mcg) Males

(mcg) Females

(mcg) Pregnancy

(mcg) Lactation

(mcg)

0-1 600

(2,000 IU)

1-3 600

(2,000 IU)

4-8 900

(3,000 IU)

9-13 1,700 (5610 IU)

14-18 2,800 (9,240 IU) 2,800 (9,240 IU) 2,800 (9,240 IU) 2,800 (9,240 IU)

19+ 3,000 (10,000 IU) 3,000 (10,000 IU) 3,000 (10,000 IU) 3,000 (10,000 IU)

 

 

Retinoids are compounds that are chemically similar to vitamin A. Over the past 15 years, synthetic retinoids have been prescribed for acne, psoriasis, and other skin disorders [50]. Isotretinoin (Roaccutane® or Accutane®) is considered an effective anti-acne therapy. At very high doses, however, it can be toxic, which is why this medication is usually saved for the most severe forms of acne [51-53]. The most serious consequence of this medication is birth defects. It is extremely important for sexually active females who may become pregnant and who take these medications to use an effective method of birth control. Women of childbearing age who take these medications are advised to undergo monthly pregnancy tests to make sure they are not pregnant.

What are the health risks of too many carotenoids?

Provitamin A carotenoids such as beta-carotene are generally considered safe because they are not associated with specific adverse health effects. Their conversion to vitamin A decreases when body stores are full. A high intake of provitamin A carotenoids can turn the skin yellow, but this is not considered dangerous to health.

 

Clinical trials that associated beta-carotene supplements with a greater incidence of lung cancer and death in current smokers raise concerns about the effects of beta-carotene supplements on long-term health; however, conflicting studies make it difficult to interpret the health risk. For example, the Physicians Health Study compared the effects of taking 50 mg beta-carotene every other day to a placebo in over 22,000 male physicians and found no adverse health effects [54]. Also, a trial that tested the ability of four different nutrient combinations to help prevent the development of esophageal and gastric cancers in 30,000 men and women in China suggested that after five years those participants who took a combination of beta-carotene, selenium, and vitamin E had a 13% reduction in cancer deaths [55]. In one lung cancer trial, men who consumed more than 11 grams/day of alcohol (approximately one drink per day) were more likely to show an adverse response to beta-carotene supplements [1], which may suggest a potential relationship between alcohol and beta-carotene.

 

The IOM did not set ULs for carotene or other carotenoids. Instead, it concluded that beta-carotene supplements are not advisable for the general population. As stated earlier, however, they may be appropriate as a provitamin A source for the prevention of vitamin A deficiency in specific populations [1].

Vitamin A intakes and healthful diets

According to the 2005 Dietary Guidelines for Americans, "Nutrient needs should be met primarily through consuming foods. Foods provide an array of nutrients and other compounds that may have beneficial effects on health. In certain cases, fortified foods and dietary supplements may be useful sources of one or more nutrients that otherwise might be consumed in less than recommended amounts. However, dietary supplements, while recommended in some cases, cannot replace a healthful diet [56]." For more information about building a healthful diet, refer to the Dietary Guidelines for Americans (http://www.health.gov/dietaryguidelines/dga2005/document/pdf/DGA2005.pdf) and the U.S. Department of Agriculture's food guidance system (My Pyramid; http://www.mypyramid.gov).

 

 

Posted Date:

6/22/2005

Updated:

4/23/2006 8:27 PM

 

 

References

 

1. Institute of Medicine. Food and Nutrition Board. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. National Academy Press, Washington, DC, 2001.

2. Gerster H. Vitamin A-functions, dietary requirements and safety in humans. Int J Vitam Nutr Res 1997;67:71-90. [PubMed abstract]

3. Futoryan T, Gilchrest BE. Retinoids and the skin. Nutr Rev 1994;52:299-310. [PubMed abstract]

4. Hinds TS, West WL, Knight EM. Carotenoids and retinoids: A review of research, clinical, and public health applications. J Clin Pharmacol 1997;37:551-8. [PubMed abstract]

5. Ross AC, Gardner EM. The function of vitamin A in cellular growth and differentiation, and its roles during pregnancy and lactation. Adv Exp Med Biol 1994;352:187-200. [PubMed abstract]

6. Ross AC. Vitamin A and retinoids. In: Modern Nutrition in Health and Disease. 9th Edition (edited by Shils ME, Olson J, Shike M, Ross AC). Lippincott Williams and Wilkins, New York, 1999, pp. 305-27.

7. Ross AC, Stephensen CB. Vitamin A and retinoids in antiviral responses. FASEB J 1996;10:979-85. [PubMed abstract]

8. Semba RD. The role of vitamin A and related retinoids in immune function. Nutr Rev 1998;56:S38-48. [PubMed abstract]

9. Ross DA. Vitamin A and public health: Challenges for the next decade. Proc Nutr Soc 1998;57:159-65. [PubMed abstract]

10. Harbige LS. Nutrition and immunity with emphasis on infection and autoimmune disease. Nutr Health 1996;10:285-312. [PubMed abstract]

11. de Pee S, West CE. Dietary carotenoids and their role in combating vitamin A deficiency: A review of the literature. Eur J Clin Nutr 1996;50 Suppl 3:S38-53. [PubMed abstract]

12. Bendich A, Olson JA. Biological actions of carotenoids. FASEB J 1989:3;1927-32 [PubMed abstract]

13. Olson JA, Kobayashi S. Antioxidants in health and disease: Overview. Proc Soc Exp Biol Med 1992;200:245-7. [PubMed abstract]

14. Olson JA. Benefits and liabilities of vitamin A and carotenoids. J Nutr 1996;126:1208S-12S. [PubMed abstract]

15. Pavia SA, Russell RM. Beta-carotene and other carotenoids as antioxidants. J Am Coll Nutr 1999;18:426-33. [PubMed abstract]

16. Guthrie HA, Picciano MF. Human Nutrition. Mosby, St. Louis, MO, 1995.

17. Harrison EH. Mechanisms of digestion and absorption of dietary vitamin A. Annu Rev Nutr 2005;25:5.1-5.18.

18. U.S. Department of Agriculture, Agricultural Research Service. 2004. USDA National Nutrient Database for Standard Reference, Release 17. Nutrient Data Laboratory Home Page, http://www.nal.usda.gov/fnic/foodcomp.

19. Bialostosky K, Wright JD, Kennedy-Stephenson J, McDowell M, Johnson CL. Dietary Intake of Macronutrients, Micronutrients, and Other Dietary Constituents: United States 1988-94. Vital and Health Statistics 2002;11(245):6-99. US Department of Agriculture, Agricultural Research Service, 2004.

20. U.S. Department of Health and Human Services. Advance Data from Vital and Health Statistics. Dietary Intake of Selected Vitamins for the United States Population: 1999-2000. Centers for Disease Control and Prevention. National Center for Health Statistics. Number 339, 2004.

21. Rodrigues MI, Dohlman CH. Blindness in an American boy caused by unrecognized vitamin A deficiency. Arch Ophthalmol 2004;122:1228-9.

22. Sommer A. Nutritional Blindness: Xeropthalmia and Keratomalacia. Oxford University Press, London and New York, 1982.

23. Ross AC. Vitamin A status: Relationship to immunity and the antibody. Proc Soc Exp Biol Med 1992;200:303-20. [PubMed abstract]

24. Stephens D, Jackson PL, Gutierrez Y. Subclinical vitamin A deficiency: A potentially unrecognized problem in the United States. Pediatr Nurs 1996;22:377-89. [PubMed abstract]

25. Butler JC, Havens PL, Sowell AL, Huff DL, Peterson DE, Day SE, Chusid MJ, Benning RA, Circo R, Davis JP. Measles severity and serum retinol (vitamin A) concentration among children in the United States. Pediatrics 1993;91:1176-81. [PubMed abstract]

26. Leo MA, Lieber CS. Alcohol, vitamin A, and beta-carotene: Adverse interactions, including hepatotoxicity and carcinogenicity. Am J Clin Nutr 1999;69:1071-85. [PubMed abstract]

27. Committee on Infectious Diseases. Vitamin A treatment of measles. Pediatrics 1993;91:1014-5. [PubMed abstract]

28. Tursi A. Gastrointestinal motility disturbances in celiac disease. J Clin Gastroenterol 2004;38:642-5.

29. Krok KL, Lichtenstein GR. Nutrition in Crohns disease. Curr Opin Gastroenterol 2003;19:148-53.

30. Kiehne K, Gunther R, Folsch U. Malnutrition, steatorrhoea and pancreatic head tumour. Eur J Gastroenterol Hepatol 2004;16:711-3.

31. Bell CS, Shepherd RW. Editorial: Optimising nutrition in cystic fibrosis. J Cyst Fibros 2002;1:47-50.

32. Fontham ETH. Protective dietary factors and lung cancer. Int J Epidemiol 1990;19:S32-S42. [PubMed abstract]

33. Koo LC. Diet and lung cancer 20+ years later: more questions than answers? Int J Cancer 1997;Suppl10:22-9. [PubMed abstract]

34. Rock CL, Jacob RA, Bowen PE. Update on the biological characteristics of the antioxidant micronutrients: Vitamin C, vitamin E, and the carotenoids. J Am Diet Assoc 1996;96:693-702. [PubMed abstract]

35. Albanes D, Heinonen OP, Taylor PR, Virtamo J, Edwards BK, Rautalahti M, Hartman AM, Palmgren J, Freedman LS, Haapakoski J, Barrett MJ, Pietinen P, Malila N, Tala E, Lippo K, Salomaa ER, Tangrea JA, Teppo L, Askin FB, Taskinen E, Erozan Y, Greenwald P, Huttunen JK. Alpha-tocopherol and beta-carotene supplement and lung cancer incidence in the alpha-tocopherol, beta-carotene cancer prevention study: Effects of base-line characteristics and study compliance. J Natl Cancer Inst 1996;88:1560-70. [PubMed abstract]

36. Redlich CA, Blaner WS, Van Bennekum AM, Chung JS, Clever SL, Holm CT, Cullen MR. Effect of supplementation with beta-carotene and vitamin A on lung nutrient levels. Cancer Epidemiol Biomarkers Prev 1998;7:211-14. [PubMed abstract]

37. Pryor WA, Stahl W, Rock CL. Beta carotene: from biochemistry to clinical trials. Nutr Rev 2000;58:39-53.

38. National Institutes of Health. Osteoporosis prevention, diagnosis, and therapy. NIH Consensus Statement Online, 2000 March 27-29, 2000:1-36.

39. National Osteoporosis Foundation. NOF osteoporosis prevention-risk factors for osteoporosis. 2003. http://www.nof.org/prevention/risk.htm.

40. Binkley N, Krueger D. Hypervitaminosis A and bone. Nutr Rev 2000;58:138-44. [PubMed abstract]

41. Forsyth KS, Watson RR, Gensler HL. Osteotoxicity after chronic dietary administration of 13-cis-retinoic acid, retinyl palmitate or selenium in mice exposed to tumor initiation and promotion. Life Sci 1989;45:2149-56. [PubMed abstract]

42. Whiting SJ, Lemke B. Excess retinol intake may explain the high incidence of osteoporosis in northern Europe. Nutr Rev 1999;57:249-50. [PubMed abstract]

43. Johansson S, Melhus H. Vitamin A antagonizes calcium response to vitamin D in man. J Bone Miner Res 2001;16:1899-1905. [PubMed abstract]

44. Melhus H, Michaelsson K, Kindmark A, Bergstrom R, Holmberg L, Mallmin H, Wolk A, Ljunghall S. Excessive dietary intake of vitamin A is associated with reduced bone mineral density and increased risk of hip fracture. Ann Intern Med 1998;129:770-8. [PubMed abstract]

45. Feskanich D, Singh F, Willett WC, Colditz GA. Vitamin A intake and hip fractures among postmenopausal women. J Am Med Assoc 2002;287:47-54. [PubMed abstract]

46. Michaelsson K, Lithell H, Vessby B, Mehus H. Serum retinol levels and the risk of fracture. N Engl J Med 2003;348:287-94.

47. Ballew C, Galuska D, Gillespie C. High serum retinyl esters are not associated with reduced bone mineral density in the third National Health and Nutrition Examination Survey, 1988-94. J Bone Miner Res 2001;16:2306-12. [PubMed abstract]

48. Bendich A, Langseth L. Safety of vitamin A. Am J Clin Nutr 1989;49:358-71. [PubMed abstract]

49. Udall JN, Greene HL. Vitamin update. Pediatr Rev 1992;13:185-94. [PubMed abstract]

50. Soprano DR, Soprano KJ. Retinoids as teratogens. Annu Rev Nutr 1995;15:111-32. [PubMed abstract]

51. Orafanos CE, Zouboulis CC, Almond-Roesler B, Geilen CC. Current use and future potential role of retinoids in dermatology. Drugs 1997;53:358-88. [PubMed abstract]

52. Meigel WN. How safe is oral isotretinoin? Dermatology 1997;195:22-28, 38-40. [PubMed abstract]

53. Hathcock JN. Vitamin and Mineral Safety. Council for Responsible Nutrition, Washington, DC, 1997, pp. 26-27.

54. Hennekens CH, Buring JE, Manson JE, Stampfer M, Rosner B, Cook NR, Belanger C, LaMotte F, Gaziano JM, Ridker PM, Willett W, Peto R. Lack of effect of long-term supplementation with beta-carotene on the incidence of malignant neoplasm and cardiovascular disease. N Eng J Med 1996;334:1145-9. [PubMed abstract]

55. Blot WJ, Li J-Y, Taylor PR, Guo W, Dawsey S, Wang G-Q, Yang CS, Zheng S-F, Gail M, Li G-Y, Yu Y, Liu B-Q, Tangrea J, Sun Y-H, Liu F, Fraumeni JF, Zhang Y-H, Li B. Nutrition intervention trials in Linxian, China: supplementation with specific vitamin/mineral combinations, cancer incidence, and disease-specific mortality in the general population. J Natl Cancer Inst 1993;85:1483-92. [PubMed abstract]

56. U.S. Department of Health and Human Services, U.S. Department of Agriculture. Dietary Guidelines for Americans 2005. Washington, DC: U.S. Government Printing Office, 2005. http://www.health.gov/dietaryguidelines/dg...pdf/DGA2005.pdf.

57. U.S. Department of Agriculture. MyPyramid.gov. 2005. http://www.mypyramid.gov/.

 

 

[MommaDogs]

This is a very good write up of vitamin A, included in it's entirety here.

 

http://westonaprice.org/search-results.htm...p;sa=Search#888

 

Vitamin A Saga

By Sally Fallon and Mary G. Enig, PhD

The discovery of vitamin A and the history of its application in the field of human nutrition is a story of bravery and brilliance, one that represents a marriage of the best of scientific inquiry with worldwide cultural traditions; and the suborning of that knowledge to the dictates of the food industry provides a sad lesson in the use of power and influence to obfuscate the truth.

A key player in this fascinating story is Weston A. Price, who discovered that the diets of healthy traditional peoples contained at least ten times as much vitamin A as the American diet of his day. His work revealed that vitamin A is one of several fat-soluble activators present only in animal fats and necessary for the assimilation of minerals in the diet. He noted that the foods held sacred by the peoples he studied, such as spring butter, fish eggs and shark liver, were exceptionally rich in vitamin A.

All traditional cultures recognized that certain foods were necessary to prevent blindness. In his pioneering work, Nutrition and Physical Degeneration, Weston Price tells the story of a prospector who, while crossing a high plateau in the Rocky Mountains, went blind with xerophthalmia, due to a lack of vitamin A. As he wept in despair, he was discovered by an Indian who caught him a trout and fed him "the flesh of the head and the tissues back of the eyes, including the eyes."1 Within a few hours his sight began to return and within two days his eyes were nearly normal. Several years previous to the travels of Weston Price, scientists had discovered that the richest source of vitamin A in the entire animal body is that of the retina and the tissues in back of the eyes.

Many cultures used liver, another excellent source of vitamin A, for various types of blindness.2 The liver was first pressed to the eye and then eaten, a ritual through which the patient directed the healing powers of liver to the afflicted sense organ. The Egyptians described this cure at least 3500 years ago. Similar practices have been described in 18th-century Russia, rural Java in 1978 and among the inhabitants of Newfoundland in 1929. Other cultures used the liver of shark. Hippocrates (460-327 BC) prescribed liver soaked in honey for blindness in malnourished children. Assyrian texts dating from 700 BC and Chinese medical writings from the 7th century AD both call for the use of liver in the treatment of night blindness. A 12th-century Hebrew treatise recommends pressing goat liver to the eyes, followed by eating of the liver. In the Middle Ages, the Dutch physician Jacob van Laerlandt (1235-1299) wrote the following:

Who does not at night see right

Eats the liver of goat

He will then see better at night.

VITAMIN-A BRAVERY

Night blindness was a recurring problem among sailors on long voyages but by the advent of the great European navies, the wisdom of traditional liver therapy was largely ignored. It took brave dedication to the scientific method to confirm the validity of the ancient treatments. The first to do this was Eduard Schwarz (1831-1862), a ship's doctor on an Austrian frigate that was sent around the world on a scientific exploration. Before his departure from Vienna, several physicians had asked Schwartz to test the old folk remedy of boiled ox liver against night blindness. On the voyage, 75 of the 352 men developed the condition. Every evening when dusk came, they lost their vision and had to be led about like the blind. Schwartz fed them ox or pork liver and found that the night vision in all of the afflicted was restored.

The cure was "a true miracle," said Schwartz in his published report, which stated emphatically that night blindness was a nutritional disease. For this he was viciously attacked by the medical profession, which accused him of "frivolity" and "self-aggrandizement." Three years after his return from the expedition, the discredited physician died of TB. He was 31. The use of vitamin-A-rich foods for tuberculosis had not yet been discovered.

In 1904, the Japanese physician M. Mori described xerophthalmia in undernourished children whose diet consisted of rice, barley, cereals "and other vegetables." Xerophthalmia is a condition that progresses from night blindness to dissolution of the cornea and finally the bursting of the eye. He treated the children with liver and also cod liver oil with excellent results. In fact, he found that cod liver oil was even more effective than liver in restoring visual function. Mori described it as "an excellent, almost specific medication. . . Indeed, in most cases, the effect is so rapid that by evening the children with night blindness are already dancing around briskly, to the joy of their mothers." Cod liver oil also helped reverse keratomalacia, a condition associated with severe nutritional deficiencies and characterized by corneal ulceration, extreme dryness of the eyes and infection.

At the end of the First World War, a physician named Bloch discovered that a diet containing whole milk, butter, eggs and cod liver oil cured night blindness and keratomalacia. In one important experiment, Bloch compared the results when he fed one group of children whole milk and the other margarine as the only fat. Half of the margarine-fed children developed corneal problems while the children receiving butterfat and cod liver oil remained healthy.

The actual discovery of vitamin A is credited to a researcher named E. V. McCollum. He was curious why cows fed wheat did not thrive, became blind and gave birth to dead calves, while those fed yellow corn had no health problems. The year was 1907 and by this time, scientists were able to determine the levels of protein, carbohydrate, fat and minerals in food. The wheat and corn used in McCollum's experiments contained equal levels of minerals and macronutrients. McCollum wondered whether the wheat contained a toxic substance, or whether there was something lacking in the wheat that was present in yellow maize?

In order to solve the puzzle, McCollum hit upon the idea of using small animals like mice or rats rather than cows for nutrition experiments-they ate less, took up less space, reproduced rapidly and could be given controlled diets. Like many good ideas, this one met with considerable opposition. McCollum worked in the Wisconsin College of Agriculture and was told by the dean "to experiment with economically valuable animals-the rat was a pest to farmers!" McCollum was forced to work secretly in the basement of the Agriculture Hall where he studied the effects of various diets on colonies of rats. He discovered that rats fed pure protein, pure skim milk, sugar, minerals and lard or olive oil for fat failed to grow. When he added butterfat or an extract of egg yolk to their diets, their health was restored. He discovered a fat-soluble factor in certain foods that was essential for growth and survival. This was named "fat-soluble factor A" as opposed to other accessory dietary factors, called "water-soluble B."

Research by Osbourne and Mendel, published just five months after McCollum's study, found that cod liver oil produced the same results as butter in rat studies, thus confirming the early work of Mori in Japan. Continued experiments helped scientists determine that vitamin A was colorless, but often associated in foods with beta-carotene, which was yellow. In the 1930s, researchers discovered that vitamin A is formed by the conversion of beta-carotenes in the intestinal mucosa of animals and humans.

The scientific term for vitamin A is retinol, because of its presence in the retina of the eye. The role of retinol in vision was elucidated by a number of brilliant scientists, beginning in 1877 with a German, W. Kuhne, who discovered that the purple retinas from dark-adapted frogs turned yellow when exposed to light. The purple color is restored in a complex biochemical cycle involving vitamin A, which makes vision possible. Other scientists demonstrated the role of vitamin A in cell differentiation, bone development, reproduction and immune system function. Weston Price confirmed the value of vitamin A in traditional diets during his studies of primitive peoples carried out during the 1930s and 1940s.

Due to the outstanding scientific work of these and many other researchers, the administration of cod liver oil to growing children-a tradition found among Arctic peoples such as the Scandanivians and Eskimos-became standard practice until after the Second World War. Ironically, as Americans have stopped giving cod liver oil to their children, programs to administer vitamin A to children in Africa and Asia have had astonishing success in preventing blindness and infectious disease. This vitamin-A-treatment program was the brainchild of yet another brave researcher, Alfred Sommer, an ophthalmologist at Johns Hopkins University, who patiently lobbied for an international program after observing the wonderful effects of vitamin-A supplementation in Indonesia and Nepal.

In recent decades, much vitamin-A research has focussed on its role in preventing cancer, and its use in combination with nontoxic therapies in the treatment of cancer. Unfortunately, research on the anticarcinogenic properties of vitamin A has not been widely adopted. Perhaps the most tragic example is Dr. Max Gerson, who treated many cases of terminal cancer with excellent results using raw liver juice, a rich source of vitamin A. In 1946, he testified before a US congressional committee on the success of his treatment, but it was subsequently ignored.3 In 1973, Dr. Kanematsu Sigiura of the Sloan Kettering Institute published the results of studies on mammary tumors in mice using high doses of vitamin A and a derivative of seeds called laetrile. He observed complete regression of all the tumors in a total of five mice. The final report noted that "Dr. Sigiura has never observed complete regression of these tumors in all his cosmic experience with other chemotherapeutic agents." Nevertheless, just a few months later, spokesmen for Sloan Kettering flatly denied that there was any value in the therapy.4

VITAMIN-A VAGARY

While the ongoing process of research into vitamin A and its effects is a boon to children and adults throughout the world, modern agriculture and food processing conglomerates gain nothing from this knowledge. Confinement farming practices effectively prevent vitamin A from incorporation into animal foods and the processing industry would rather use vegetable oils than animal fats. Some vegetable oils contain carotenes but they do not contain true vitamin A. Only animal fats contain vitamin A and vitamin A is present in large amounts only when the animals have a source of carotenes or vitamin A in the diet, such as green pasture, insects and fish meal.

Unfortunately, the vast majority of popular books on nutrition insist that humans can obtain vitamin A from fruits and vegetables. Even worse, FDA regulations allow food processors to label carotenes as vitamin A. The label for a can of tomatoes says that tomatoes contain vitamin A, even though the only source of true vitamin A in the tomatoes is the microscopic insect parts. The food industry, and the lowfat school of nutrition that the industry has spawned, benefit greatly from the fact that the public has only vague notions about vitamin A. In fact, most of the foods that provide large amounts of vitamin A-butter, egg yolks, liver, organ meats and shellfish-have been subject to intense demonization.

Under optimal conditions, humans can indeed convert carotenes to vitamin A. This occurs in the upper intestinal tract by the action of bile salts and fat-splitting enzymes. Of the entire family of carotenes, beta-carotene is most easily converted to vitamin A. Early studies indicated an equivalency of 4:1 of beta-carotene to retinol. In other words, four units of beta-carotene were needed to produce one unit of vitamin A. This ratio was later revised to 6:1 and recent research suggests an even higher ratio.5 This means that you have to eat an awful lot of vegetables and fruits to obtain even the daily minimal requirements of vitamin A, assuming optimal conversion.

But the transformation of carotene to retinol is rarely optimal. Diabetics and those with poor thyroid function, a group that could well include at least half the adult US population, cannot make the conversion. Children make the conversion very poorly and infants not at all - they must obtain their precious stores of vitamin A from animal fats6- yet the low-fat diet is often recommended for children. Strenuous physical exercise, excessive consumption of alcohol, excessive consumption of iron (especially from "fortified" white flour and breakfast cereal), use of a number of popular drugs, excessive consumption of polyunsaturated fatty acids, zinc deficiency and even cold weather can hinder the conversion of carotenes to vitamin A,7 as does the lowfat diet.

Carotenes are converted by the action of bile salts, and very little bile reaches the intestine when a meal is low in fat. The epicure who puts butter on his vegetables and adds cream to his vegetable soup is wiser than he knows. Butterfat stimulates the secretion of bile needed to convert carotenes from vegetables into vitamin A, and at the same time supplies very easily absorbed true vitamin A. Polyunsaturated oils also stimulate the secretion of bile salts but can cause rapid destruction of carotene unless antioxidants are present.

It is very unwise, therefore, to depend on plant sources for vitamin A. This vital nutrient is needed for the growth and repair of body tissues; it helps protect mucous membranes of the mouth, nose, throat and lungs; it prompts the secretion of gastric juices necessary for proper digestion of protein; it helps to build strong bones and teeth and rich blood; it is essential for good eyesight; it aids in the production of RNA; and contributes to the health of the immune system. Vitamin-A deficiency in pregnant mothers results in offspring with eye defects, displaced kidneys, harelip, cleft palate and abnormalities of the heart and larger blood vessels. Vitamin A stores are rapidly depleted during exercise, fever and periods of stress. Even people who can efficiently convert carotenes to vitamin A cannot quickly and adequately replenish vitamin A stores from plant foods.

Foods high in vitamin A are especially important for diabetics and those suffering from thyroid conditions. In fact, the thyroid gland requires more vitamin A than the other glands, and cannot function without it.8 And a diet rich in vitamin A will help protect the diabetic from the degenerative conditions associated with the disease, such as problems with the retina and with healing.

Weston Price considered the fat-soluble vitamins, especially vitamin A, to be the catalysts on which all other biological processes depend.9 Efficient mineral uptake and utilization of water-soluble vitamins require sufficient vitamin A in the diet. His research demonstrated that generous amounts of vitamin A insure healthy reproduction and offspring with attractive wide faces, straight teeth and strong sturdy bodies. He discovered that healthy primitives especially value vitamin-A-rich foods for growing children and pregnant mothers. The tenfold disparity that Price discovered between primitive diets and the American diet in the 1940s is almost certainly greater today as Americans have forsworn butter and cod liver oil for empty, processed polyunsaturates.

In Third World communities that have come into contact with the West, vitamin-A deficiencies are widespread and contribute to high infant mortality, blindness, stunting, bone deformities and susceptibility to infection.10 These occur even in communities that have access to plentiful carotenes in vegetables and fruits. Scarcity of good quality dairy products, a rejection of organ meats as old fashioned or unhealthful, and a substitution of vegetable oil for animal fat in cooking all contribute to the physical degeneration and suffering of Third World peoples.

Supplies of vitamin A are so vital to the human organism that mankind is able to store large quantities of it in the liver and other organs. Thus it is possible for an adult to subsist on a fat-free diet for a considerable period of time before overt symptoms of deficiency appear. But during times of stress, vitamin A stores are rapidly depleted. Strenuous physical exercise, periods of physical growth, pregnancy, lactation and infection are stresses that quickly deplete vitamin A stores. Children with measles rapidly use up vitamin A, which can result in irreversible blindness. An interval of three years between pregnancies allows mothers to rebuild vitamin A stores so that subsequent children will not suffer diminished vitality.

One aspect of vitamin A that deserves more emphasis is its role in protein utilization. Kwashiorkor is as much a disease of vitamin-A deficiency, leading to impaired protein absorption, as it is a result of absence of protein in the diet. High-protein, lowfat diets are especially dangerous because protein consumption rapidly depletes vitamin-A stores. Children brought up on high-protein, lowfat diets often experience rapid growth. The results-tall, myopic, lanky individuals with crowded teeth, and poor bone structure, a kind of Ichabod Crane syndrome-are a fixture in America. High-protein, lowfat diets can even cause blindness as occurred once in Guatemala where huge amounts of instant nonfat dry milk were donated in a food relief program.11 The people who consumed the dried milk went blind. Primitive peoples understood this principle instinctively, which is why they never ate lean meat and always consumed the organ meats of the animals that served them for food.

Growing children actually benefit from a diet that contains considerably more calories as fat than as protein.12 A high-fat diet that is rich in vitamin A will result in steady, even growth, a sturdy physique and high immunity to illness.

The great discrepancy between what science has discovered about vitamin A and what nutrition writers promote in the popular press contributes to awkward moments. The New York Times has been a strong advocate for lowfat diets, even for children, yet a recent NYT article noted that vitamin-A-rich foods like liver, egg yolk, cream and shellfish confer resistance to infectious diseases in children and prevent cancer in adults.13 A Washington Post article hailed vitamin A as "cheap and effective, with wonders still being (re)discovered," noting that recent studies have found that vitamin-A supplements help prevent infant mortality in Third World countries, protect measles victims from severe complications and prevent mother-to-child transmission of HIV virus.14 The article lists butter, egg yolk and liver as important sources of vitamin A, but claims, unfortunately, that carotenes from vegetables are "equally important."

Vitamin-A vagary confuses the public and contributes to continued acceptance of lowfat dogma, even among science writers.

VITAMIN-A KNAVERY

Even worse than vitamin-A vagary is vitamin-A knavery in the form of concerns that vitamin A may be toxic in more than the minuscule RDA-recommended amounts. In fact, so great is the propaganda against the vitamin that obstetricians and pediatricians are now warning patients to avoid foods containing vitamin A!

Recently an "expert" panel recommended lowering the RDA (recommended daily allowance) for vitamin A from 5000 IU daily to about 2500 IU and has set an upper limit of about 10,000 IUs for women. The panel was headed by Dr. Robert Russell of Tufts University, who warned that intake over the "upper limit" may cause irreversible liver damage and birth defects-a ridiculous statement in view of the fact that just a few decades ago pregnant women were routinely advised to take cod liver oil daily and eat liver several times per week. One tablespoon of cod liver oil contains at least 15,000 IU and one serving of liver can contain up to 40,000 IU vitamin A. Russell epitomizes the establishment view when he insists that vitamin-A requirements can be met with one-half cup of carrots daily.

The anti-vitamin-A campaign began in 1995 with the publication of a Boston University School of Medicine study published in the New England Journal of Medicine.15 "Teratogenicity of High Vitamin A Intake," by Kenneth J. Rothman and his colleagues, correlates vitamin-A consumption among more than 22,000 pregnant women with birth defects occurring in subsequent offspring. The study received extensive press coverage in the same publications that had earlier extolled the benefits of vitamin A. "Study Links Excess Vitamin A and Birth Defects" by Jane Brody appeared on the front page of the New York Times on October 7, 1995; on November 24, 1995, the Washington Times reported: "High doses of vitamin A linked to babies' brain defects."

When a single study receives front-page coverage, it's important to take a closer look, especially as earlier research discovered the importance of vitamin A in preventing birth defects. In fact, the defects listed as increasing with increased vitamin A dosage-cleft lip, cleft palate, hydrocephalus and major heart malformations-are also defects of vitamin A deficiency.

In the study, researchers asked over 22,000 women to respond to questionnaires about their eating habits and supplement intake before and during pregnancy. Their responses were used to determine vitamin-A status. As reported in the newspapers, researchers found that cranial-neural-crest defects increased with increased dosages of vitamin A; what the papers did not report was the fact that neural tube defects decreased with increased vitamin A consumption, and that no trend was apparent with musculoskeletal, urogenital or other defects. The trend was much less pronounced, and less statistically significant, when cranial-neural-crest defects were correlated with vitamin-A consumption from food alone.

The study is compromised by a number of flaws. Vitamin-A status was assessed by the inaccurate method of recall and questionnaires; and no blood tests were taken to determine the actual usable vitamin-A status of the mothers. Researchers did not weight birth defects according to severity; thus we do not know whether the defects of babies born to mothers taking high doses of vitamin A were serious or minor compared to those of mothers taking lower amounts.

The most serious flaw was that researchers failed to distinguish between manufactured vitamin A in the form of retinol, found in supplements and added to fabricated foods, from natural vitamin-A complex, present with numerous co-factors, from vitamin-A-containing foods. It is well known that synthetic vitamins are less biologically active, hence less effective, than naturally occurring vitamins. This is especially true of the fat-soluble vitamins like vitamin A, because these tend to be more complex molecules, with numerous double bonds and a multiplicity of forms. Natural vitamin A occurs as a mixture of various isomers, aldehydes, esters, acids and alcohols. Pure retinoic acid, a metabolite of vitamin A used to treat adult acne, is well known to cause birth defects. Apparently pure retinol has teratogenic properties in high amounts as well.

Researchers found that cranial-neural-crest defects increased in proportion to the amount of retinol from supplements consumed during the first trimester of pregnancy (although the total number of defects remained stable up to 15,000 IU daily). Research into vitamin A has indicated that many factors interfere with its absorption and utilization. Inadequate fat in the diet, poor production of bile salts, low enzyme status, and compromised liver function can all interfere with the uptake and usage of vitamin A, especially when given as a supplement in the form of retinol, rather than as a component of whole foods. It may be that the teratogenic effects of commercial vitamin-A preparations are exacerbated in women whose dietary practices and general health status are poor. Some researchers believe that synthetic vitamin A interferes with the proper utilization of natural vitamin A from foods.

Pure retinol is added to many fabricated foods like margarine, breakfast cereals and pizza. The study made no distinction between those women whose vitamin A was supplied by whole animal foods and those who ingested retinol added to margarine, white flour and extruded breakfast cereals-foods which contain many other factors that can cause birth defects. Natural vitamin A provided by liver, eggs, butter, cream and cod liver oil is well recognized as providing excellent protection against birth defects.

Distinctions between synthetic and natural vitamin A have been absent in the extensive media coverage of this study-on the contrary, the newspaper reports contain implied warnings against pregnant women eating liver, dairy products, meat and eggs, but none against eating fabricated foods like margarine and breakfast cereals to which synthetic vitamin A is added. And there has been no media coverage for subsequent studies, which found that high levels of vitamin A did not increase the risk of birth defects. A study carried out in Rome, Italy found no congenital malformations among 120 infants exposed to more than 50,000 IU of vitamin A per day.16 A study from Switzerland looked at blood levels of vitamin A in pregnant women and found that a dose of 30,000 IU per day resulted in blood levels that had no association with birth defects.17

VITAMIN-A SLAVERY

While scientists in America are creating confusion and fear about vitamin A, WHO and UNICEF vitamin-A-distribution programs in Africa and Asia have been extremely successful in reducing blindness and death among both children and adults. Vitamin A is more cost effective in saving lives and preventing suffering than immunizations and drugs and it can be administered with 2-cent capsules. The program does not undermine traditional cultures or foodways and is easily carried out on the village level.

But this kind of success doesn't sit well with the food and pharmaceutical industries because it strengthens village life and lessens the market for drugs and processed foods. Fulsome with praise, the "big guns of the international food supply system" have joined in a "public-private partnership" to get in on the program.18 Kellogg, Cargill, Monsanto and Procter & Gamble have pioneered the addition of vitamin A to margarine, vegetable oil, wheat flour, sugar and breakfast cereals-even to MSG! At a formal luncheon hosted by Hillary Clinton, the corporate executives and leaders of various relief groups announced their goal of showing "indigenous food companies. . . how to add vitamin A to foods that low-income people eat." In other words, vitamin A will be used to promote processed foods to villagers in Africa and Asia in the guise of humanitarian relief. Low income people in America eat margarine and other processed foods, but low-income people in the Third World eat foods grown by farmers and processed locally by artisans.

And when people refuse to eat processed foods, the "big guns" have devised another stratagem-genetically engineering rice to produce carotenes. Those who promote the so-called "golden" rice as a solution to the vitamin-A problem are either woefully ignorant or unabashedly corrupt. Golden rice containing carotenes can't provide true vitamin A to the world's children but it will further the trend of pushing their parents off the farm and into ghastly slums.

In the process of showing "indigenous food companies. . . how to add vitamin A to foods. . ." and of inserting genes for producing carotenes into rice, the multinational corporations will strengthen their grip on the world's food supply, leading to a disruption of village life and what Indian writer Vandana Shiva calls "food dictatorship." If the conglomerates have their way, programs to promote golden rice and "enriched" processed foods will replace programs to distribute vitamin-A capsules, increasing the suffering of children and worldwide economic slavery.

What can we in the west do to foil the nefarious plans of the food-and-pharmaceutical-complex in nations less prosperous than our own? The answer is simple: cut off their funding at the source by refusing to spend money on their products. Boycott processed foods; avoid pharmaceutical drugs. The better way to physical and economic health is through foods containing vitamin A.

REFERENCES

1. Price, Weston A. Nutrition and Physical Degeneration. Price-Pottenger Nutrition Foundation, San Diego, CA, p 280.

2. The history outlined here has been expertly compiled by G Wolf. "A History of Vitamin A and Retinoids." The FASEB Journal, July 1996, 10:1102-1107.

3. Gerson, M., MD. A Cancer Therapy: Results of Fifty Cases. Totality Books, Del Mar, CA, 1958.

4. Griffin, G. E. World Without Cancer. American Media, Westlake Village, CA, 1974, pp 462-3.

5. Solomons, N. W. and J. Bulus. "Plant sources of provitamin A and human nutriture." Nutrition Review, Springer Verlag New York, Inc, July 1993, 51:1992-4.

6. Jennings, I. W. Vitamins in Endocrine Metabolism. Charles C. Thomas Publisher, Springfield, Illinois.

7. Dunne, L. J. Nutrition Almanac, Third Edition, McGraw-Hill Publishing Company, 1990.

8. Jennings, Op Cit.

9. Price, Op Cit.

10. Solomons, Op Cit.

11. Personal Communication, Ruth Rosevear

12. Protein calories should comprise about 15 percent of the diet. Fat calories in children's diets should be greater than 40 percent of total calories.

13. Angler, Natalie. "Vitamins Win Support as Potent Agents of Health," New York Times, March 10, 1992.

14. Brown, David. "It's Cheap and Effective, With Wonders Still Being (Re)discovered." The Washington Post, November 7,1994.

15. Rothman, K. J. and others. "Teratogenicity of high vitamin A intake." New England Journal of Medicine. November 23, 1995 333(21):1414-5.

16. Mastroiacovo, P. and others. "High vitamin A intake in early pregnancy and major malformations: a multicenter prospective controlled study." Teratology. January 1999 59(1):1-2.

17. Wiegand, U. W. and others. "Safety of vitamin A: recent results." International Journal of Vitamin and Nutrition Research. 1998, 68(6):411-6.

18. Mann, J. "Saving Young Lives With a 2-Cent Capsule." The Washington Post, March 17, 1999.

________________________________________

SIDEBAR ARTICLES

THE SUCCESS OF VITAMIN A

One of the most successful programs in the history of nutrition science is the global campaign to distribute high-dose vitamin-A capsules to children throughout Africa and Asia. Launched in 1997, the global campaign is a partnership between UNICEF and the World Health Organization (WHO) as well as the governments of Canada, the United Kingdom, the Netherlands, Japan and the United States Agency for International Development (USAID). The program has been particularly successful in Nepal where groups of local women known as Female Community Health Volunteers help distribute the capsules throughout the rugged terrain. In 2000, over 90 percent of Nepalese children had received their yearly dosage of vitamin A.

Although the vitamin A distributed is synthetic and not the natural form derived from fish oils, it is the animal form of vitamin A (retinol), not carotenes. Children six to twelve months old receive two doses of 100,000 units per year; children over 12 months receive two doses of 200,000 per year. According to Werner Schultink, head of the Nutrition Section at UNICEF headquarters in New York, infant and child mortality drops about 23 percent when vitamin A levels are adequate. The program in Nepal costs just over $2 million per year, less than $1 per child (Reuter's 2/12/01).

________________________________________

CONVERSION OF CAROTENES TO VITAMIN A

The many conditions that interfere with the conversion of carotenes in plant foods to vitamin A include:

• Being an infant or child

• Diabetes

• Low Thyroid Function

• Low Fat Intake

• Intestinal Roundworms

• Diarrhea

• Pancreatic Disease

• Celiac Disease

• Sprue

________________________________________

THE MYTH OF VITAMIN A TOXICITY

Typical of the orthodox medical view of vitamin A is the following statement, posted at WebMD.com: "Vitamin A can be very toxic when taken in high-dose supplements for long periods of time and can affect almost every part of the body, including eyes, bones, blood, skin, central nervous system, liver, and genital and urinary tracts. Symptoms include dizziness, nausea, vomiting, headache, skin damage, mental disturbances and, in women, infrequent periods. Severe toxicity can cause blindness and may even be life-threatening. Liver damage can occur in children who take RDA-approved adult levels over prolonged periods of time or in adults who take as little as five times the RDA-approved amount for seven to ten years. In children, chronic overdose can cause fluid on the brain and other symptoms similar to those in adults. Pregnant women who take amounts not much higher than RDA levels increase the risk for birth defects in their children. High consumption of vitamin A may also increase the risk of gastric cancer and the risk of osteoporosis and fractures in women."

The Merck Manual describes vitamin-A toxicity in less hysterical terms. Acute vitamin-A poisoning can occur in children after taking a single dose of synthetic vitamin A in the range of 300,000 IU or a daily dosage of 60,000 IU for a few weeks. Two fatalities have been reported from acute vitamin-A poisoning in children, which manifests as increased intracranial pressure and vomiting. For the vast majority, however, recovery after discontinuation is "spontaneous, with no residual damage."

In adults, according to the Merck Manual, vitamin-A toxicity has been reported in arctic explorers who developed drowsiness, irritability, headaches and vomiting, with subsequent peeling of the skin, within a few hours of ingesting several million units of vitamin A from polar bear or seal liver. Again, these symptoms cleared up with discontinuation of the vitamin-A rich food. Other than this unusual example, however, only vitamin-A from "megavitamin tablets containing vitamin A. . . when taken for a long time" has induced acute toxicity, that is, 100,000 IU synthetic vitamin-A per day taken for many months.

Unless you are an arctic explorer, it is virtually impossible to develop vitamin-A toxicity from food. The putative toxic dose of 100,000 IU per day would be contained in 3 tablespoons of high vitamin cod liver oil, 6 tablespoons of regular cod liver oil, two-and-one-half 100-gram servings of duck liver, about three 100-gram servings of beef liver, seven pounds of butter or 309 egg yolks. Even synthetic vitamin A is not toxic when given as a single large dose or in small amounts on a daily basis. Children in impoverished areas of the world are routinely given two 100,000-unit doses of retinol per year for infants and two 200,000-unit doses for children over 12 months.

The tragedy is that misplaced concern about vitamin-A toxicity has led doctors to advise pregnant women to avoid foods containing vitamin A, and parents to avoid giving cod liver oil to their babies. Yet the early books on the feeding of pregnant women and infants recommended generous doses of cod liver oil and frequent liver consumption for pregnant women and two teaspoons of cod liver oil per day for babies three months and older. A majority of our medical problems would clear up very quickly if the populace would return to eating liver and embrace the use of cod liver oil-our finest superfoods.

________________________________________

GETTING IT WRONG

"Vitamin A can be found in fish liver oils, animal livers and green and yellow fruits and vegetables." —Prescription for Nutritional Healing by James F. Balch, MD and Phillis A. Balch, CNC. (However, the authors include the following warning at the end of their section on vitamin A: "Diabetics should avoid beta-carotene as should hypothyroid individuals, because they cannot convert beta-carotene to vitamin A.")

"Cod liver oil used to be taken routinely as a source of vitamin A. But many experts now believe that as a nutritional aid, the oil is obsolete. We can only consume vitamin A directly in the meat of animals-liver is the richest source. But bright orange fruits and vegetables and dark, leafy greens contain beta-carotene which our bodies convert into the vitamin. . . Before the days of refrigerated trucks and mass distribution of produce, vitamin A deficiency was an enormous problem. . . . But today most people have access to a wide range of produce year-round. What's more, beta-carotene supplements are also widely available." —Article on WebMD.com by Karen Cullen, RD, PhD

"Vitamin A is found in animal produce and beta-carotene, a vitamin-A-type compound. It is found in the yellow pigments of vegetables. . . If it is not needed, it remains as beta-carotene; if needed, it is converted into vitamin A. . . vitamin A supplements [are] not necessary."—Enhancing Fertility Naturally by Nicky Wesson

"Vitamin A is found in the form of betacarotene in leafy green vegetables, carrots, sweet potatoes, winter squash and cantelope in adequate amounts to supply a child's daily needs. . . " —Dr. Attwood's Low-Fat Prescription for Kids by Dr. Charles R. Attwood

"Vitamin A's toxicity depends on its form. Only retinol and the other varieties found in animal foods are capable of doing much harm. Carotenoids, the vegetable sources of vitamin A, don't seem to be toxic even when extraordinarily large amounts are consumed." —The University of California San Diego Nutrition Book by Paul Saltman, PhD, Joel Gurin and Ira Mothner

"The carotenes. . . are the main source of vitamin A." Basic Food Chemistry by Frank E. Lee, PhD "Yellow, deep orange/red and dark green vegetables and fruits. . . are high in vitamin A. . . " —The Breast Cancer Survival Manual by John Link, MD

"Vitamin A taken too enthusiastically can be toxic, since it is stored in the liver. Beta-carotene, however, is not converted into vitamin A unless the body requires it, and you cannot suffer from toxic levels of it." —The Endometriosis Answer Book by Niels H Lauersen and Constance deSwaan

________________________________________

VITAMIN A-THE MIRACLE NUTRIENT

Vitamin A supplementation of children in Asia and Africa has been extremely effective in reducing the rates of infection, diarrhea, anemia and blindness (Reuter's 2/12/01). African and Asian children receiving vitamin-A supplements grow faster, have better hemoglobin values and die 30-60 percent less frequently than nonsupplemented peers (J Nutr Jan 1989 119(1):96-100).

Vitamin A supplementation can reduce the incidence of malaria. Children in Papua New Guinea given high doses of vitamin A had a 30 percent lower incidence of malaria than those receiving a placebo (The Lancet, 1999, 354:203-9).

Vitamin A plays a vital regulating role in the immune system. Vitamin A deficiency leads to a loss of ciliated cells in the lung, an important first line defense against pathogens. Vitamin A promotes mucin secretion and microvilli formation by mucosa, including the gastrointestinal tract mucosa. Vitamin A regulates T-cell production and apoptosis (programmed cell death) (Nutrition Reviews 1998;56:S38-S48).

HIV transmission is closely correlated with levels of vitamin A in mothers. A study in Malawi, Africa found that mothers with the highest levels of vitamin A had an HIV transmission rate of just 7.2 percent (Celia Farber, "A Timely Firestorm," www.ironminds.com).

Treatment with megadoses of vitamin A (100,000 IU per day) resulted in a 92 percent cure rate of menorrhagia (excessive menstrual bleeding) at Johannesburg General Hospital in South Africa (S Afr Med J 1977).

Lack of vitamin A interferes with optimal function of the hippocampus, the main seat of learning. Scientists at the Salk Institute for Biological Studies in San Diego, California, found that removing vitamin A from the diets of mice diminished chemical changes in the brain considered the hallmarks of learning and memory (Proc Natl Acad Sci, Sep 25, 2001 98(20):11714-9).

Natural vitamin A helps reconnect retinoid receptors critical for vision, sensory perception, language processing and attention in autistic children. Use of cod liver oil helps children recover from autism due to the DPT vaccine. The pertussis toxin interferes with retinoid receptors in the brain (Med Hypothesis, Jun 2000 54(6):979-83).

Vitamin A can be helpful in the treatment of psoriasis. Researchers found that patients suffering from severe psoriasis had low blood levels of vitamin A (Acta Derm Venereol Jul 1994 74(4):298-301).

In stroke victims, those with high levels of vitamin A are more likely to recover without damage (The Lancet, Mar 25, 1998, pp 47-50).

Vitamin A protects against lung and bladder cancers in men (Alt Cancer Inst Monogr Dec 1985 69:137-42). Fourteen out of 20 patients with prostate cancer achieved total remission and five achieved partial remission using vitamin A as part of a natural cancer therapy in Germany (Drugs Exp Clin Res 2000;26(65-6):249-52).

Vitamin A was used successfully by Dr. L. J. A. Loewenthal, to combat tropical ulcers in Uganda (S Afr Med J Dec 24 1983 64(27):1064-7).

Vitamin A has also been used successfully to treat a skin condition called Kyrle's disease (Cutis Dec 1982 30(6):753-5, 759). Elderly persons who consume adequate vitamin A are less prone to leg ulcers (Veris Newsletter Dec 1999;15(4):5).

Chronic vitamin-A deficiency causes degeneration of the structures of the ear. Decreased auditory function in humans is associated with low vitamin-A levels. (Arch Otorhinolaryngol 1982;234(2):167-73).

Vitamin A inhibits the effects of phytic acid and increases absorption of iron from whole wheat. (Arch Latinoam Nutr Sep 2000;50(3):243-8). Vitamin A supplementation increases absorption of iron and folic acid in women in Bangladesh (Am J Clin Nutr Jul 2001;74(1):108-15).

Use of vitamin A supplements reduces the risk of cataracts (Am J Ophthalmol Jul 2001;132(1):19-26).

________________________________________

SOURCES OF VITAMIN A

Listed below are approximate levels of vitamin A in common foods, in IUs per 100 grams:

• High-vitamin cod liver oil 230,000

• Regular cod liver oil 100,000

• Duck liver 40,000

• Beef liver 35,000

• Goose liver 31,000

• Liverwurst sausage (pork) 28,000

• Lamb liver 25,000

It should be noted that these amounts can vary according to how the animals are fed. Weston Price noted a huge variation in vitamin-A content of butter according to the season. In addition, absorption of vitamin A varies according to the food. Research carried out during the 1940s indicates that vitamin A is more easily absorbed from butter than from other foods.

The US Recommended Daily Allowance of vitamin A is currently 5,000 IU per day (and may possibly be lowered to 2500 IU per day). From the work of Weston Price, we can assume that the amount in primitive diets was about 50,000 IU per day, which could be achieved in a modern diet by consuming generous amounts of whole milk, cream, butter and eggs from pastured animals; beef or duck liver several times per week; and 1 tablespoon regular cod liver oil or 1/2 tablespoon high-vitamin cod liver oil per day.

________________________________________

ARE CAROTENES SAFE?

Are carotenes safe in large doses, as claimed? Dependence on carotenes for vitamin A calls on large reserves of enzymes to make the conversion. In their fascinating book Nutrition and Evolution, Michael Crawford and David Marsh note that in animals, "if any function can be delegated to another organism it leaves the disk space free to perform some new function or to perform an old one better." The cat species does not synthesize vitamin A from carotenes. "If they had to synthesize their own vitamin A . . . it would take up a significant amount of their disk space." Cats get vitamin A from their prey, whose ability to synthesize vitamin A from carotenes compromises other functions, such as night vision and quickness of movement. While medical orthodoxy claims that consumption of large amounts of carotenes has no downside, it is possible that dependence on carotenes for vitamin A, even in those who are good converters, compromises other biochemical functions in subtle ways.

The so-called nontoxic betacarotene supplements contain a synthetic form of carotene, just one of 50 or 60 carotenes found in the typical diet. The biological activity of synthetic betacarotene is much lower than that of the natural complexes of carotenes and, in fact, may put stress on the immune system Studies with humans and rats given synthetic betacarotene found an increase in white blood cells. In cancer trials, synthetic betacarotenes were not found to be protective. In fact, in one study, patients given synthetic betacarotene had worse results than controls (NEJM April 1994 330:(15);891-895).

About the Authors

Mary G. Enig, PhD is an expert of international renown in the field of lipid biochemistry. She has headed a number of studies on the content and effects of trans fatty acids in America and Israel, and has successfully challenged government assertions that dietary animal fat causes cancer and heart disease. Recent scientific and media attention on the possible adverse health effects of trans fatty acids has brought increased attention to her work. She is a licensed nutritionist, certified by the Certification Board for Nutrition Specialists, a qualified expert witness, nutrition consultant to individuals, industry and state and federal governments, contributing editor to a number of scientific publications, Fellow of the American College of Nutrition and President of the Maryland Nutritionists Association. She is the author of over 60 technical papers and presentations, as well as a popular lecturer. Dr. Enig is currently working on the exploratory development of an adjunct therapy for AIDS using complete medium chain saturated fatty acids from whole foods. She is Vice-President of the Weston A Price Foundation and Scientific Editor of Wise Traditions as well as the author of Know Your Fats: The Complete Primer for Understanding the Nutrition of Fats, Oils, and Cholesterol, Bethesda Press, May 2000. She is the mother of three healthy children brought up on whole foods including butter, cream, eggs and meat.

Sally Fallon is the author of Nourishing Traditions: The Cookbook that Challenges Politically Correct Nutrition and the Diet Dictocrats (with Mary G. Enig, PhD), a well-researched, thought-provoking guide to traditional foods with a startling message: Animal fats and cholesterol are not villains but vital factors in the diet, necessary for normal growth, proper function of the brain and nervous system, protection from disease and optimum energy levels. She joined forces with Enig again to write Eat Fat, Lose Fat, and has authored numerous articles on the subject of diet and health. The President of the Weston A. Price Foundation and founder of A Campaign for Real Milk, Sally is also a journalist, chef, nutrition researcher, homemaker, and community activist. Her four healthy children were raised on whole foods including butter, cream, eggs and meat.

 

[MommaDogs]

I found this interesting because as stated elsewhere on this site, during hard physical labor, you'll need extra energy... how about extra muscle, testosterone (for men, obviously), etc.

 

www.westonaprice.org/men/vitaminabodybuilding.html

 

Vitamin A:

The Forgotten Bodybuilding Nutrient

By Chris Masterjohn

The dense forest of bodybuilding nutrition contains a paradox: the quantity of information available is abundant, but the wisdom of traditional diets to satisfy the primary concerns of bodybuilders is sparse and hard to find. Typical recommendations include very low-fat diets rich in protein foods like salmon and chicken.

You will search in vain through mainstream men's health magazines to find so much as a mention of the importance of vitamin A to bodybuilding. Yet this nutrient is essential to muscle-building and may be the bodybuilder's most potent weapon. Vitamin A is necessary for the utilization of protein and the production of testosterone and other growth factors. In fact, one human study, discussed below, found the administration of vitamin A and iron to have results equivalent to the administration of testosterone itself. Rather than advocating the consumption of vitamin-A rich foods such as liver and natural food-based supplements such as cod liver oil, mainstream men's health writers are advocating diets very high in protein, which deplete vitamin A reserves, leaving one to wonder whether the athletes who resort to over-the-counter steroid supplements might be able to achieve similar results by consuming a traditional diet, rich in vitamin A.

Vitamin A and Testosterone

Abundant animal research indicates the importance of vitamin A to the production of testosterone. Vitamin A crosses the blood-testis barrier in its alcohol form as retinol, where it is stored in the Sertoli cells and converted as needed to its more biologically active form, retinoic acid. Experiments with rats show that greater concentrations of vitamin A in the testes increase basal testosterone secretion, as well as transferrin, which is responsible for the transport of iron; and a variety of growth factors including IGF-binding protein 4 (which transports IGF), androgen-binding protein (which transports androgens), transforming growth factor-beta (which causes cell growth but suppresses cancer) and steroidogenic acute regulatory protein (which is responsible for the transport of cholesterol into the mitochondria for its conversion to steroids). Vitamin A also decreases estrogen production in the male testes. Rats that are deficient in vitamin A experience decreased testosterone until the accessory sex organs atrophy, indicating that vitamin A not only aids in, but is essential to, testosterone production.1

One experiment using guinea pigs, which corroborates the many experiments done with rats, found a decrease in plasma testosterone associated with a deficiency in vitamin A.2 A human study comparing the dietary intakes of 155 pairs of male twins found a correlation between testosterone levels and vitamin A intake.3

The most compelling study is one that assigned 102 teenage boys with short stature and delayed puberty into four groups: a control, a testosterone-supplemented group, a vitamin A- and iron-supplemented group, and a group that received both testosterone and the nutritional supplementation. All treatments were effective in inducing growth and puberty, whereas the control group did not gain weight or begin puberty in the same period of time. What is most amazing is that the degree of growth acceleration was similar in the testosterone-treated group and the vitamin A-treated group. Pubertal onset occurred in 9-12 months in the testosterone group, and by 12 months in the vitamin-A group.4

This study suggests two things. The first is that the growth problems these boys experienced could have been avoided if their parents only had known the importance of serving a meal with liver on a weekly basis, as liver is very rich in both vitamin A and iron. The second is that, with equivalent hard work and dedication, athletes and body builders may be able to achieve similar results from their training by taking high-vitamin cod liver oil and eating foods rich in vitamin A on a regular basis as others receive from the common practice of supplementing with testosterone precursors.

Vitamin A and Prostate Cancer

Although some researchers have expressed concern that androgens such as testosterone may be involved in the etiology of prostate cancer, from vitamin A we can expect only more good news. Scientists in one controlled study administered doses of cyproterone acetate, an anti-androgen, and testosterone proprionate, to rats, followed by N-methyl-N-nitrosourea, a carcinogen, with one group treated with large doses of vitamin A. The incidence of prostate cancer in the group not treated with vitamin A was 65 percent, while only 18 percent and 20 percent of vitamin A-treated rats experienced dorsolateral and anterior prostate cancer, respectively.5

Vitamin A and Protein Utilization

The utilization of protein requires vitamin A. Several animal studies have shown that liver reserves of vitamin A are depleted by a high dietary intake of protein, while vitamin A increases in non-liver tissues. One explanation for this is that adequate protein is necessary for vitamin A transport. In one study researchers fed radioactively-labeled vitamin A to rats on low-protein and high-protein diets, using the amount of radioactivity present in exhaled gases, urine and feces as a measure of the metabolism of vitamin A, and found that vitamin A is indeed used at a higher rate on a high-protein diet.6

Vitamin A is not only depleted by a high intake of protein, but it is also necessary for the synthesis of new protein, which is the goal of the bodybuilder. Rats fed diets deficient in vitamin A synthesize protein at a lower rate than rats fed adequate vitamin A.7 Cultured skeletal muscle cells increase the amount of protein per cell when exposed to vitamin A and D, but not when exposed to vitamin D alone.8

Eat Your Liver

Bodybuilders and other athletes interested in gaining muscle have an interest in boosting their levels of testosterone and other growth factors and maximizing their utilization of protein and its incorporation into muscle cells. Typical recommendations usually include very high amounts of protein, but exclude foods like liver that are high in vitamin A, and low-fat recommendations all but banish vitamin A entirely from the diet by excluding foods such as full-fat milk. The combination of a high-protein diet that depletes vitamin A and a low-fat diet that fails to provide vitamin A is a clear recipe for deficiency of this vital nutrient. Exercises that elicit a high demand for testosterone, such as squats and deadlifts, are often recommended for muscle growth, but without vitamin A the body cannot meet that demand for testosterone. It's high time for athletes to forget the modern mantras and remember the dietary wisdom of the past, achieving a lean, muscular physique through traditional foods such as liver, egg yolks, full-fat milk, butter from grass-fed cows and cod liver oil.

About the Author

Chris Masterjohn is the author of several Wise Traditions articles and the creator and maintainer of Cholesterol-And-Health.Com, a website dedicated to extolling the virtues of cholesterol and cholesterol-rich foods. He has authored two items accepted for publication in peer-reviewed journals: a letter in an upcoming issue of the Journal of the American College of Cardiology criticizing the conclusions of a recent study on saturated fat and a full-length feature in an upcoming issue of Medical Hypotheses proposing a molecular mechanism of vitamin D toxicity. Masterjohn holds a Bachelor's degree in History and is preparing to pursue a PhD in Molecular and Cellular Biology. He is also a Weston A. Price Foundation Local Chapter Leader in West Brookfield, Massachusetts.

 

Editor's Note: Many health conscious individuals avoid cod liver oil and other foods rich in vitamin A because of concerns about vitamin A toxicity. Yet, according to the Merck Manual, vitamin A poisoning is rare. In adults, vitamin A toxicity has been reported in Arctic explorers who developed drowsiness, irritability, headaches and vomiting, with subsequent peeling of the skin, within a few hours of ingesting several million units of vitamin A from polar bear or seal liver. These symptoms cleared up with discontinuation of the vitamin A rich food. Other than this unusual example, however, only vitamin A from "megavitamin tablets containing vitamin A. . . when taken for a long time" has induced acute toxicity, that is, 100,000 IU synthetic vitamin A per day taken for many months. Unless you are an Arctic explorer, it is very difficult to develop vitamin A toxicity from food. The putative toxic dose of 100,000 IU per day would be contained in 3 tablespoons of high vitamin cod liver oil, 6 tablespoons of regular cod liver oil, two-and-one-half 100-gram servings of duck liver, 150 grams of beef liver, seven pounds of butter or 309 egg yolks. Bodybuilders undergoing strenuous exercise can consume even higher amounts without adverse effects. For further information see "Vitamin A Saga."

REFERENCES

1. Livera, et al., "Regulation and Perturbation of Testicular Functions by Vitamin A" (Review), Reproduction (2002) 124, 173-180

2. Nayyar, et. al., "Alterations in binding characteristics of peripheral benzodiazepine receptors in testes by vitamin A deficiency in guinea pigs," Mol Cell Biochem. 2000 Aug;211(1-2):47-50

3. Bishop, et. al., "The effect of nutritional factors on sex hormone levels in male twins," Genet Epidemiol. 1988;5(1):43-59.

4. Zadik, et. al., "Vitamin A and iron supplementation is as efficient as hormonal therapy in constitutionally delayed children," Clin Endocrinol (Oxf). 2004 Jun; 60(6):682-7.

5. McCormick, et. al., "Chemoprevention of rat prostate carcinogenesis by 9-cis-retinoic acid," Cancer Res. 1999 Feb 1;59(3):521-4.

6. Furusho, et. al., "Tissue specific-distribution and metabolism of vitamin A are affected by dietary protein levels in rats," Int J Vitam Nutr Res. 1998;68(5):287-92

7. Narbonne, et. al., "Protein metabolism in vitamin A deficient rats. II. Protein synthesis in striated muscle," Ann Nutr Aliment. 1978;32(1):59-75.

8. Stio, et. al., "Synergistic effect of vitamin D derivatives and retinoids on C2C12 skeletal muscle cells," IUBMB Life. 2002 Mar;53(3):175-81

[gramma lois]

Well is it any wonder now why our mothers' made sure we had spring doses of cod liver oil - and not in capsule form either - a generous tablespoon I'm stocking up on cod liver oil.

 

IU (International Units) and RE (Retinal Equivalent) Dosages:

 

5000 IU (1000 RE): Males 11 years and over

 

4000IU (800 RE): Femailes 11 years and over

 

5000 IU (1000 RE): During Pregnancy

 

6000 IU (1200 RE): During Lactation

 

"Since 1974 the designation RE (retinol equivalent) has been the preferred method of indicating the dose of vitamin A. Most food value charts at the present time give both the IU and the RE (retinol equivalent)."

 

Source: Back to Eden by Jethro Kloss - revised edition 2005

[Ambergris]

I know someone who drank heavily for over 30 years, but made an invariable habit of taking one Beta Carotene capsule every time he thought it was morning. (He was too drunk, sometimes, to realize it was evening instead.) He loves collards, and will eat them all winter. Fried chicken livers are another favorite treat. He also drinks lots and lots of water. At age 51, his liver was biopsied because he had a very rare form of Hep C (Type 4). According to his puzzled liver specialist, he has the liver of a 20-year-old who never drank alcohol in his life.

[MommaDogs]

Two page printout for your files (I can send by email in Word format if you want a pretty version, PM me with your email and I'll get it right out) - still can't figure out tables, so if anyone can help, please let me know. All sources for the below post are listed above this post.

Common Name

Vitamin A

Chemical Name

Retinol (preformed vitamin)

Beta Carotene (precursor vitamin)

 

Sources of Retinol

Liver, Cod liver oil, egg yolks, grass fed butter, whole milk, fish eggs, shark liver **note: there can be a huge variation according to how the animals are fed, and the seasons. Butter seems to be the most easily absorbed.

 

Sources of precursor

Sweet potatoes, leafy greens, red palm oil, bee larvae, carrots, cantaloupe

 

Functions

Night vision

Growth and development of bones and teeth

Skin health

Secretion of mucus by the cells lining the respiratory, urinary, and intestinal tracts (part of immune function)

Aids in the normal reproductive processes

Needed for carbohydrate metabolism in the liver

Essential for proper smell, hearing and taste

Aids in the prevention of certain types of cancer

Helps regulate the immune system, which helps prevent or fight off infections by making white blood cells that destroy harmful bacteria and viruses. Vitamin A also may help lymphocytes (a type of white blood cell) fight infections more effectively.

 

From the work of Weston Price, we can assume that the amount in primitive diets was about 50,000 IU per day, which could be achieved in a modern diet by consuming generous amounts of whole milk, cream, butter and eggs from pastured animals; beef or duck liver several times per week; and 1 tablespoon regular cod liver oil or 1/2 tablespoon high-vitamin cod liver oil per day.

 

Special considerations Must have good fats in your diet in order to convert beta carotene to

vitamin A in your body, which occurs in your intestine. Only a small portion is utilized in the body, so larger amounts of beta carotene are needed to obtain adequate doses of the vitamin

 

The chemical form of retinol (ie made in a lab, not found in food) has been shown

to have toxicity. Although highly unlikely, care should be taken when consuming fortified foods during pregnancy as serious defects can occur if the mother supplements with chemical Vitamin A

 

Carotenoids are not as well absorbed by the body, and as such, retinol from animal sources remains the best source of Vitamin A Things that may interfere with this conversion are as follows:

• Being an infant or child

• Diabetes

• Low Thyroid Function

• Low Fat Intake

• Intestinal Roundworms

• Diarrhea

• Pancreatic Disease (fat malabsorption)

• Celiac Disease (fat malabsorption)

• Sprue

• Crohn’s disease (fat malabsorption)

 

 

 

Toxicity Excess of 50,000 IU daily over a period of time

The studies in toxicity typically study chemically created vitamin A

Please note that some acne medication contains synthetic Vitamin A and can cause reproductive harm, including spontaneous abortion and birth defects.

 

Deficiency Night blindness is the first symptom

Poor vision in dim light (night blindness)

Dry, scaly, itchy skin

Increased susceptibility to infections, specially in the respiratory tract

Changes in the eyes that may lead to blindness. The eyes become dry, swollen, and infected.

Slow wound healing

Poor bone growth in children

Defective enamel on teeth and an increased number of cavities

Loss of taste and smell

Stunting of body growth

 

 

Storage Majority in the liver

 

Stability Stable in heat or alkali

Unstable in acids, light and oxygen

 

RDA

Age (years) Children

(mcg RAE) Males

(mcg RAE) Females

(mcg RAE) Pregnancy

(mcg RAE) Lactation

(mcg RAE)

1-3 300

(1,000 IU)

4-6 400

(1,320 IU)

9-13 600

(2,000 IU)

14-18 900

(3,000 IU) 700

(2,310 IU) 750

(2,500 IU) 1,200

(4,000 IU)

19+ 900

(3,000 IU) 700

(2,310 IU) 770

(2,565 IU) 1,300

(4,300 IU)

[Stephanie]

What a GREAT thread! Thank you, did you continue this elsewhere with the other vitamins?

[MommaDogs]

You know, I was just thinking about this today. Sorry everyone for dropping the ball... I got so busy at work, I haven't had much time for anything other than sleeping in my personal life. I will get back to it soon, I promise.