HSR'S ANNUAL GUIDE TO VITAMINS

HSR'S ANNUAL GUIDE TO VITAMINS

This second edition of HSR's Annual Guide to Vitamins is intended to assist you, the retailer, in your endeavor to educate your customers. Each article addresses the latest science related to a specific vitamin. Note that each article in this section is appropriate for photocopying. As a retailer, you have our express permission to photocopy the articles in this section for distribution to your customers.

This edition of HSR's Annual Guide to Vitamins includes the following articles:

• Vitamin A / Beta Carotene
• B Vitamins
• Vitamin C
• Vitamin E

Next Month

Look for the second edition of HSR's Annual Guide to Herbs with consumer-friendly articles on St. John's wort, kava kava, garlic, ginseng, echinacea, ginkgo biloba and more.

Vitamin A

The first vitamin to be officially identified, vitamin A is available in two different forms--retinol, a preformed vitamin A, and carotene pigments (the best-known of which is beta carotene), which are provitamin A. Like some other essential vitamins, a significant percentage of Americans do not attain even the minimal requirements of vitamin A or beta carotene. The Reference Daily Intake (RDI) for vitamin A is 3,300 International Units (IUs). Anywhere from 10,000 to 15,000 IUs of beta carotene is needed to meet the RDI for vitamin A. There is no formal RDI for beta carotene, as it is not officially recognized as an essential nutrient.

A study published in the Journal of the American Dietetic Association stated that only 25 percent of a sample population of Americans achieved the daily intake level of beta carotene suggested by the American Dietetic Association (ADA). The study also found that 50 percent of men and 44 percent of women do not meet the dietary guidelines for vitamin A, which is based upon the intake needed to prevent xerophthalmia.¹ Eventually leading to blindness, xerophthalmia is a condition in which the eyes become dry, ulcers develop on the cornea and the eyelids become dry and sticky. The disease is the leading preventable cause of blindness in developing countries.

Vitamin A is necessary for many other areas and functions of the body, including growth of the base layer of skin cells. Lack of vitamin A can lead to growth retardation, defective teeth and gum formation, weakened immune system and fatigue. The need for vitamin A may increase in instances of trauma, anxiety, stress, smoking and alcohol use. The elderly, alcoholics and teenagers are the three groups that most commonly have vitamin A deficiencies. Vitamin A supplements also may be beneficial for those who have difficulty absorbing fats. Recent studies have suggested that high blood levels of vitamin A may help prevent cancer, particularly lung cancer. Vitamin A also is used to treat skin disorders such as acne and psoriasis.

While beta carotene's benefits are partly due to its conversion to Vitamin A in the body, it has therapeutic effects in and of itself. Research indicates that beta carotene is an antioxidant that reduces the risk of cardiovascular disease and multiple forms of cancer. It also has been shown to stimulate immune system processes by increasing the numbers of immune cells such as B and T lymphocytes.²

Vitamin A is found in fish and liver oils, egg yolks and all milk products. Supplemental Vitamin A often is made from cod liver oil, synthetic vitamin A palmitate and vitamin A acetate. Beta carotene is converted to vitamin A by our bodies, and good sources of beta carotene include dark leafy vegetables, broccoli, carrots, squash, pumpkins, sweet potatoes, cantaloupe, apricots and pink grapefruit. Cooking does not destroy beta carotene. Beta carotene supplements are available in synthetic forms or from algae and palm oil, which may possess greater beneficial effects than synthetic forms.

Vitamin A is fat-soluble and joins to fatty acids in the intestinal lining where it combines with other substances before being transferred to the liver, where 90 percent of the body's vitamin A is stored. Beta carotene is absorbed in the wall of the small intestinal lining where some of it is converted to vitamin A. Beta carotene also can be stored in the liver, lungs, kidneys, skin and fat.

Because vitamin A is fat-soluble and can be stored in the liver for long periods of time, there exists the possibility for toxicity. It would be difficult to intake toxic levels of vitamin A from diet alone, but vitamin A supplements do pose a potential risk.³ Signs of vitamin A toxicity include headaches, chapped lips, dry skin and joint and muscle pain. Beta carotene is nontoxic.

In recent years, researchers have taken particular notice of the role of vitamin A/beta carotene in the prevention of cancer, cardiovascular disease and infections:

• High doses of vitamin A complemented by a dose of vitamin E administered to children in Bangladesh cured them of the bacterial disease, shinellosis, according to a report in the British Medical Journal. According to the researchers, vitamin A reduces the severity of acute shinellosis in children living in areas where vitamin A deficiency is a major health problem.⁴
• A puzzling study appearing in the Journal of the American Geriatrics Society indicated that zinc supplements improved some measures of immune function, while vitamin A supplements blunted others in a group of institutionalized but relatively healthy older adults. The researchers reported that they cannot explain the negative effects of vitamin A, especially since there is evidence that the essential nutrient improves immune function.⁵
• According to a study in the American Journal of Clinical Nutrition, men taking beta carotene supplements had significantly greater NK (key immune cells that have antitumor activity and help fight infections) cell activity compared with those taking placebo.⁶
• In a study published in International Journal of Vitamin and Nutrition Research, the inhibitory effects of beta carotene and vitamin A on precancerous lesions in rats was compared when administered during early promotion of liver cancer. The incidence and total number of nodules in the liver were significantly decreased in the beta carotene group compared to the untreated group. Vitamin A-supplemented rats exhibited a lower number of liver nodules but incidence remained at 100 percent.⁷
• A study published in the International Journal of Vitamin and Nutrition Research discovered that smoking lowers carotenoid levels in the body, requiring higher daily intakes for smokers.⁸
• A study published in Contemporary International Medicine concluded that women in the highest quintile of beta carotene intakes had a 22 percent lower risk of coronary heart disease, while men in the highest quintile were 25 percent less likely to suffer from a coronary heart problem.⁹

References 1. Millen B, et al. "Population Nutrient Intake Approaches Dietary Recommendations: 1991 to 1995 Framingham Nutritional Studies." Journal for the American Dietetic Association. 97:742-749 (1997). 2. Haas, E. Staying Healthy with Nutrition: The Complete Guide to Diet and Nutritional Medicine. Berkeley: Celestial Arts, 1992. p.95. 3. Haas, p. 97. 4. Hossain S, et al. "Single Dose Vitamin A Treatment in Acute Shigellosis in Banglandeshi Children." British Medical Journal. 316:422-426 (1998). 5. Fortes C. et al. "The Effect of Zinc and Vitamin A Supplementation on Immune Response in an Older Population." Journal of the American Geriatrics Society. 46(1) (1998). 6. Santos MS, et al. "Beta-Carotene-Induced Enhancement of Natural Killer Cell Activity in Elderly Men: An Investigation of the Role of Cytokines." American Journal of Clinical Nutrition. 68:164-170 (1998). 7. Rizzi MB, et al. "Beta-Carotene Inhibits and Stimulates Remodeling Gamma-GT-Positive Preneoplastic Lesions." International Journal for Vitamin & Nutrition Research. 67:415-422 (1997). 8. Driskell JA, et al. "Plasma Concentrations of Carotenoids and Tocopherols in Male Long-Term Tobacco Chewers, Smokers and Nonusers." International Journal for Vitamin & Nutrition Research. 66:203-209 (1996). 9. Gaziano JM., Hennekens, CH. "Antioxidant Vitamins in the Prevention of Coronary Artery Disease." Cont. Int. Med. 7:9-14 (1995).

Vitamin B

Although the water-soluble B vitamins each have their own unique, individual properties, they possess similar coenzyme functions and are commonly found together in foods. They are very important for the normal functioning of the nervous system and are often helpful in bringing relaxation or energy to individuals who are stressed or fatigued. Additionally, B vitamins help provide energy by acting with enzymes to convert carbohydrates to glucose and also are important in fat and protein/amino acid metabolism. They also influence the health of the skin, hair, eyes and liver.

However, because the B vitamins are easily digested and absorbed, deficiencies of one or more B vitamin is not uncommon, particularly during times of fasting or dieting. Because of these deficiencies, and no known toxicity associated with their use, modest excesses should not be cause for concern. When the amount of B vitamins taken exceeds the body's needs, the excess is easily excreted in the urine.

Vitamin B1

The first B vitamin to be discovered, vitamin B1 (thiamin) is part of an enzyme system essential for nearly every cellular reaction in the body due to its involvement in energy production and carbohydrate and fatty acid metabolism.

Foods rich in thiamin include organ meats, dried beans, peas, soybeans, peanuts, poultry, egg yolks and fish. Sources of moderate amounts include plums, raisins, asparagus, broccoli and oatmeal. However, foods lose their thiamin content if exposed to ultraviolet light, sulfites, nitrites or live yeast. Cooking also destroys a portion of the nutrients.

It has been suggested that adequate thiamin levels may help prevent the accumulation of fatty deposits in the arteries and thereby reduce the progression of atherosclerosis. Thiamin also is important in the health of the nervous system, possibly because of its role in the synthesis of acetylcholine, a neurotransmitter.¹

Thiamin deficiency is rare in developed countries because refined flours and cereals are often fortified with the nutrient. But there are some risks for young children and teenagers, stressed adults, heavy exercisers, alcoholics and pregnant women.² The classic deficiency disease is beriberi, which affects the gastrointestinal, cardiovascular and peripheral nervous systems. One of the earliest signs of thiamin deficiency is reduced stamina. Depression, irritability and reduced ability to concentrate are later followed by fatigue, muscle cramps and various pains. Advanced symptoms include indigestion, constipation, insomnia, and a heaviness in the legs.

The Reference Daily Intake (RDI) for thiamin is 1.5 mg for men and women, and 1.7 mg for pregnant and lactating women. The Real Vitamin and Mineral Book by Shari Lieberman, Ph.D., and Nancy Bruning, however, recommends 25 to 300 mg for men and women for optimal general health.³

Vitamin B2

The second B complex to be discovered was vitamin B2, or riboflavin. A yellow-orange, water-soluble compound, riboflavin is part of two enzymes that are essential for tissue respiration and the metabolism of carbohydrates, amino acids and fats.

Many people may be marginally deficient in B2 as a result of taking antibiotics, oral contraceptives or alcohol, all of which deplete or interfere with the absorption or utilization of riboflavin.

Symptoms of severe riboflavin deficiency include depression, loss of appetite and decreased sensitivity to touch, as well as red and swollen lips, mouth and tongue. Deficiency can also lead to vitamin B2 anemia, which is thought to occur either because the deficiency inhibits red blood cell production, or because it causes the cells to die too early.

In a recent study conducted at the University of Liege, researchers found that a high daily dose of vitamin B2 may also be helpful in preventing migraine headaches. Researchers reported that the 55 patients receiving 400 mg of B2 daily for three months reported 37-percent fewer migraines.⁴

The RDI for vitamin B2 is 1.7 mg per day for men and women, and 2 mg for pregnant and lactating women, but optimal daily intake is 25 to 300 mg for men and women.⁴ Foods naturally high in riboflavin include cheese, yogurt, eggs, poultry, fish, spinach and beans. Other good sources include nuts, broccoli, currants and avocados. Although the vitamin is stable when heated, it is easily destroyed by light, making supplements a viable alternative, particularly for alcoholics or those with absorption difficulties.

Vitamin B3

Although the role of vitamin B3, or niacin, in metabolizing fats has made it a favored treatment for high levels of cholesterol, it has other cardiovascular functions, as well. It can be used in the treatment of anxiety, circulatory problems, and emotional or physical stress.

One of the first signs of pellagra, or niacin deficiency, is skin sensitivity to light. The skin then becomes rough, thick and dry. Other symptoms include weakness and general fatigue, anorexia, indigestion and skin eruptions. Niacin deficiency symptoms can be seen in people with a dietary intake of less than 7.5 mg per day.

Vitamin B3 is found in beef, pork, fish, milk and cheese, whole wheat, potatoes, corn and carrots. Because only small to moderate amounts of vitamin B3 occur in foods as pure niacin, it is advisable to steam, bake or stir-fry vegetables to spare as much of this vitamin as possible.

The RDI for vitamin B3 is 20 mg for men and women. Deficiencies are common in alcoholics and severely malnourished people, as well as in people with cancer, protein deficiencies or women who are taking oral contraceptives. On the average, many supplements provide at least 50 to 100 mg per day of niacin. For treatment of niacin deficiency symptoms, levels of up to 2 to 3 grams per day are not uncommon.

Vitamin B6

Vitamin B6, or pyridoxine, is a family of chemically related compounds including pyridoxamine and pyridoxal which are found in animal products, and pyridoxine, which is found in plants. The form most commonly found in foods and supplements is pyridoxine.

Vitamin B6 is necessary for the proper functioning of more than 60 enzymes. It helps in the synthesis and breakdown of amino acids, in the conversion of amino acids to carbohydrates or fat and in the conversion of one type of fat to another.

Chicken, fish, liver, kidney, pork, eggs, milk, wheat germ and brewer's yeast all are good sources of the vitamin, but long storage, canning, roasting or stewing can destroy vitamin B6.

The RDI is 2.0 mg for men and women and 2.5 mg for pregnant and lactating women. Although the Framingham Nutrition Studies published in the Journal of the American Dietetic Association indicate that 51 percent of men and 49 percent of women meet the daily guideline, many people still require more than the RDI due to a number of outside influences such as exposure to radiation, tobacco use, air pollutants, stress and the use of oral contraceptives.⁵

Vitamin B6 is available in supplemental form as pyridoxine hydrochloride, the most commonly available form, and pyridoxine phosphate, which may be better absorbed. Supplements are used to treat a variety of health conditions including asthma, cardiovascular disease, mood disorders and premenstrual syndrome.

Like vitamin B1, those at risk for a vitamin B6 deficiency are adolescents, the elderly, those on restricted diets and alcoholics. Deficiency is manifested as irritability, weakness, drowsiness, depression and poor appetite. It can cause convulsions in young children and can affect the development of a baby's nervous system if the mother was deficient during pregnancy. Although B6 is relatively nontoxic, it should be used with caution by diabetics, as it may lower blood sugar.

Vitamin B12

Vitamin B12, or cobalamin, is the only vitamin that contains an essential mineral--cobalt. It is also unique in that it is required in much smaller amounts--3 to 4 mcg; however, higher levels of up to 1 mg are often used therapeutically. It is essential for the metabolism of the nerve tissue and necessary for the health of the entire nervous system.

The body stores vitamin B12, so deficiencies may take several years to develop. The highest concentrations of B12 are found in the liver, heart, kidney, pancreas, brain, testes, blood and bone marrow--all active metabolic tissues.

Vitamin B12 is found in significant amounts in the animal protein foods. Primary food sources include most fish (especially the oily ones), crabs and oysters, eggs, milk products and meat.

Three to 4 mcg of vitamin B12 is needed in most adults to prevent deficiency, but 10 to 20 mcg daily is a good insurance level. Vitamin B12 can also be consumed through oral supplementation, most widely found as cyanocobalamin. Hydroxycobalamin is a form of B12 used in injections which are recommended in cases of B12 malabsorption.

Perhaps because of the small amount necessary to maintain recommended vitamin B12 levels, the Framingham Nutrition Studies reported that approximately 94 percent of men and 83 percent of women meet the RDI guidelines--the highest percentage of all nutrients.⁶

The classic B12 deficiency disease is pernicious anemia, which is often accompanied by weight loss, weakness, pale skin and psychological disturbances. This type of anemia occurs frequently in alcoholics, the elderly and strict vegetarians. There have been no known toxic effects from megadoses of vitamin B12.

Other B Vitamins

Other B vitamins known only by their chemical names are biotin, choline, folic acid, inositol and para-aminobenzoic acid (PABA). Biotin, choline and inositol have similar functions, while folic acid is closely related to amino acid metabolism and vitamin B12. Folic acid deficiency is one of the more common deficiencies of the B complex vitamins.⁷

In both a study published in the New England Journal of Medicine and in a report released by the Institute of Medicine's National Academy of Science, the preventative and therapeutic benefits of folic acid were extolled.

In the April 9 issue of the New England Journal of Medicine, researchers reported that cereal fortified with folic acid has the potential to increase plasma folic acid levels and reduce homocysteine levels.⁸ The Institute of Medicine's report further emphasized that up to 30 percent of people past the age of 50 have lost the ability to absorb adequate vitamin B12 from meat or dairy products.⁹

Adequate doses of folic acid are also critical in the prevention of spinal birth defects. The Institute of Medicine report urged women of childbearing age to eat specially fortified foods or take vitamin supplements daily to protect against spina bifida, a disease that affects approximately 2,500 babies each year.

The best source of folic acid is green leafy vegetables such as spinach, kale, asparagus, broccoli and beats. Whole wheat bread and milk also contain some folic acid. However, it is sensitive and easily destroyed by light, heat, any type of cooking or an acid pH below 4. It can also be lost from foods stored at room temperature for long periods of time.

The RDA for folic acid is 400 mcg in adults, 800 mcg during pregnancy and 600 mcg during lactation. But the average American diet contains only about half of this, or 220 mcg.⁸

References 1. Haas, E. Staying Healthy with Nutrition: The Complete Guide to Diet and Nutritional Medicine. Berkeley: Celestial Arts, 1992. p. 113. 2. Lieberman S, Bruning, N. The Real Vitamin & Mineral Book Second Edition. Garden City Park, N.Y.: Avery Publishing Group, 1997. p. 92. 3. Lieberman S, Bruning, N. p. 93. 4. University of Liege. Neurology, February, 1998. 5. Millen B, et al. "Population Nutrient Intake Approaches Dietary Recommendations: 1991 to 1995 Framingham Nutrition Studies." Journal of the American Dietetic Association. 97:742-749 (1997). 6. Millen B, et al. p. 745. 7. Haas, E. p. 132. 8. Malinow, Manuel, et al. "Reduction of Plasma Homocysteine Levels by Breakfast Cereal Fortified with Folic Acid in Patients with Coronary Heart Disease." The New England Journal of Medicine. 330:15;1009-1115 (1998). 9. Institute of Medicine's National Academy of Science.

Vitamin C

As one of the most popular vitamins today, vitamin C, also known as ascorbic acid, has a wide range of uses, serving a multitude of health concerns. While many consumers recognize vitamin C for its effects on the common cold, the vitamin has other important roles including its essential role in the formation and maintenance of collagen.

As the basis of connective tissue found in the skin, ligaments, cartilage, bones and teeth, collagen is responsible for the strengthening of bones and blood vessels, the anchoring of teeth to the gums and the formation of intracellular adhesive substances required for healthy body growth, tissue repair and healing wounds. Technically, Vitamin C works as a coenzyme to convert proline and lysine (both proteins) to hydroxyproline and hydroxylysine, which are both important to the collagen structure.

Vitamin C also affects the metabolism of tyrosine, folic acid and tryptophan, all substances vital to the healthy functioning of the body. Ascorbic acid helps convert tryptophan to 5-hydroxytyrptophan (5-HTP), which is a precursor to serotonin, a neurotransmitter that affects mood, sleep and appetite. The far-reaching vitamin also helps to stimulate the body's adrenal function and the release of stress hormones including adrenaline. Among its other benefits, ascorbic acid aids thyroid hormone production and assists cholesterol metabolism. More recently touted are the antioxidant properties of vitamin C. In helping to prevent oxidation of water-soluble molecules that often lead to free radicals, vitamin C has become a significant tool in combating various diseases.

This wonder vitamin is found naturally in a variety of fruits and vegetables, most notably citrus fruits like oranges, lemons, tangerines and grapefruits. Other excellent sources of the vitamin are rose hips and acerola cherries. The best vegetable sources are green and red peppers, though beneficial amounts can also be obtained from broccoli, tomatoes, asparagus and various dark leafy greens.

The best dosage of vitamin C is much debated in nutrition and science. While most animals produce relatively high levels of ascorbic acid from glucose in the liver, humans have historically had to build vitamin C levels from digesting many fruits and vegetables. What is probably the lowest dosage recommendation, the Reference Daily Intake (RDI) of vitamin C is a mere 60 mg per day, the minimum amount to prevent scurvy, a condition spurred by a vitamin C deficiency. Many nutritionists and other scientific experts differ greatly in their recommendations, however, endorsing intakes of anywhere from 100 mg to 10,000 mg per day.

Whatever the dosage, vitamin C is quickly absorbed from the intestines and is used by the body in about two hours. In fact, it usually leaves the body within three to four hours after ingestion. For this reason, Haas suggests taking vitamin C at intervals throughout the day or a time-released version once daily. Many lifestyle or environmental situations cause a rapid reduction of blood levels of vitamin C. Among the enemies of vitamin C levels, smoking and alcoholic consumption are the most noted. Other substances and situations that endanger vitamin C levels include fever, viral illness, antibiotics, cortisone, aspirin, DDT and carbon monoxide.

Generally, vitamin C is non-toxic. The worst side effects associated with over-consumption are diarrhea and, possibly, kidney stone development (calcium oxalate stones, specifically). On the other side, a deficiency of vitamin C causes scurvy, a disease marked by spongy gums, loosened teeth and bleeding under the skin.¹ Meeting the minimum dosage recommended by the RDI eliminates the risk of contracting this once prevalent disease. Also associated with low blood levels of vitamin C are various medical problems including depression, high blood pressure, arthritis, vascular fragility, allergies, ulcers and various illnesses.

The most well-known benefit of vitamin C supplementation in the past 25 years has been its defense against the common cold and flu. Starting with Pauling's 1970 discovery that the vitamin helps defend the body against the common cold, medical professionals have been increasingly aware of ascorbic acid's immune-boosting effects. In fact, vitamin C has been shown to enhance the production and activity of interferon, an antiviral substance naturally produced in the body. Haas explained that vitamin C levels need be relatively high, at least 5 to 10 g, to achieve this effect.²

Over the past year, vitamin C research has not waned.

• In Nov. 1997, researchers from the Memorial Sloan-Kettering Cancer Center published findings in the December issue of the Journal of Clinical Investigation that they had found a method of helping large vitamin C doses cross the brain barrier--a significant step towards slowing the progression of certain neurodegenerative diseases such as Alzheimer's.³
• Rounding out 1997, a population study of vitamin C's antioxidant properties showed that people with higher blood levels of the vitamin have lower levels of a marker of oxidative stress, cell damage caused by free radicals that plays a role in atherosclerosis, cancer and pulmonary disease.⁴
• Thus far, 1998 has produced a handful of studies on vitamin C supplementation. In a highly criticized study, researchers from Leicester University in England found evidence that at 500 mg per day, vitamin C supplementation ceases to be useful as an antioxidant⁵
• Also in 1998, researchers published a study in the Journal of the American College of Cardiology, reporting that vitamin C may help keep the fatty deposits inside the arteries from rupturing and causing unstable angina or heart attack.⁶ Then, on the subject of lifestyle, findings from a Spanish study published in the August issue of the Journal of the American College of Nutrition disclosed that despite equal intake levels, pregnant women who smoke have lower levels of vitamin C in their plasma and breast milk, compared to women who don't smoke.⁷

References 1. Hark, L. Vitamin C: Its Role in Health and Prevention. New Providence, N.J.: Center for Cardiovascular Education, 1996. 2. Haas, E. Staying Healthy with Nutrition: The Complete Guide to Diet and Nutritional Medecine. Berkeley: Celestial Arts, 1992. 3. Golde, D. et al. "Vitamin C Crosses the Blood-Brain Barrier in oxidized Form Through the Glucose Transporters." Journal of Clinical Investigation. 100:2842-2848 (1997). 4. Schunemann, H. et al. "Population study shows vitamin C may be antioxidant." UB News, 1997. 5. Lunec, J. et al. "Vitamin C Exhibits Pro-Oxidant Properties." Nature 392:559 (1998). 6. Vita, J. et al. "Low Plasma Ascorbic Acid Independently Predicts the Presence of an Unstable Coronary Syndrome." Journal of the American College of Cardiology. 31:980-986 (1998). 7. Ortega, R. et al.. "Smoking Reduces Vitamin C Levels in Breast Milk." Journal of the American College of Nutrition. 17:379-384 (1998).

Vitamin E

Vitamin E is a fat-soluble vitamin that performs many important functions in the body. But perhaps its most recognized role is that of an antioxidant. Through its ability to quench free radicals created by metabolic processes and environmental pollutants, vitamin E can help protect cells and other components of the body from such diseases as cancer, heart disease, premature aging and more.

Unlike other vitamins, however, a deficiency of vitamin E does not produce a specific disease with rapidly progressing symptoms. Instead, the results of vitamin E deficiencies usually take years or decades to develop, possibly resulting in a range of degenerative diseases such as cancer and heart disease. Low blood levels of vitamin E have been seen in conditions such as acne, anemia, infections, some cancers, periodontal disease, neuromuscular diseases and Alzheimer's disease.¹

Because the body cannot manufacture this essential nutrient, it must be supplied through the diet. Although foods such as seeds, nuts, grains and some uncooked vegetables such as green peas, spinach and kale are a good source of vitamin E, obtaining levels that many experts believe are needed for optimal health would require the ingestion of too much fat.²

Additionally, many nutrient and drug factors can influence vitamin E absorption and needs.³ High doses of vitamin C, for example, may decrease vitamin E absorption. Supplementation of vitamin E is, therefore, often recommended to meet the Reference Daily Intake (RDI) of 15 International Units (IUs) for adult males and 12 IUs for adult females. Currently, only 44 percent of men and 46 percent of women meet RDI levels of vitamin E, according to the Framingham Nutrition Studies published in the Journal of the American Dietetic Association.⁴

Toxicity from vitamin E intake is unlikely, and numerous studies have shown that oral intake of high levels of the nutrient produce no significant side effects in normal individuals. Vitamin E can have an anticoagulant effect, however, and it may intensify an existing coagulation defect produced by vitamin K.⁵

While there is no disputing the importance of vitamin E in maintaining good health, there is some debate over which form of vitamin E is the most bioavailable--synthetic or natural.

The term "vitamin E" describes many substances generally known as tocopherols. The word "tocopherol" was derived from the Greek word "tokos" meaning childbirth, and the verb "phero," meaning to bring forth. This is because the substance was originally identified as being involved in the fertility of rats. The suffix "ol" was added to the word to identify the alcohol contained in the molecule.

Both natural and synthetic tocopherols are used as ingredients in dietary supplements. While d-alpha-tocopherol is probably the most popular form, other natural tocopherols frequently utilized include d-beta-, d-gamma- and d-delta-. Additionally, the substances d-alpha-, d-beta-, d-gamma- and d-delta-tocotrienol have been found to exhibit vitamin E activity.⁶ Synthetic tocopherols are designated by the appearance of the letters "dl," as in dl-alpha-tocopherol.

The debate over synthetic vs. natural vitamin E was recently addressed in a study published in the March issue of the American Journal of Clinical Nutrition.⁶ In the study, 15 pregnant women given a vitamin E capsule containing both the natural and synthetic form of vitamin E five days before birth. Following delivery, researchers found nearly twice the concentration of the natural vitamin E in the mother's blood and nearly three and one-half times more of natural vitamin E than the synthetic vitamin E in their placental cord.

Additionally, a study published in the American Journal of Clinical Nutrition indicated that the bioavailability of RRR- alpha-tocopherol (a natural form of vitamin E) is almost three times higher than that of all-rac-alpha-tocopheryl acetate (a synthetic form of vitamin E). The researchers concluded that RRR-alpha-tocopherol is preferable for the treatment and prevention of disease.⁷

While this ongoing debate remains to be settled, vitamin E derived from any source has proven successful in a number of studies published in a number of peer-reviewed journals. Among them:

• A study of nearly 30,000 male smokers between the ages of 50 and 69, reported in the March 18 issue of the Journal of the National Cancer Institute, indicated that daily doses of vitamin E reduced prostate cancer risk by one-third and the disease's death rate by 41 percent.⁸
• In combination with vitamin A, 25 IU of vitamin E were shown to cure children in Bangladesh of the bacterial disease, shigellosis. Results were reported in the February 1998 issue of the British Medical Journal.⁹
• Researchers reported in the November 1997 issue of the Journal of the American Medical Association vitamins C and E may prevent fatty food from clogging the blood vessels and damaging their lining.¹⁰
• According to a study published in the June issue of Opthalmology, vitamin E has shown to sharply reduce the risk of cataracts.¹¹

References 1. Haas, E. Staying Healthy with Nutrition: The Complete Guide to Diet and Nutritional Medicine. Berkeley: Celestial Arts, 1992. p. 106. 2. Vitamin E Fact Book, VERIS Research Information Service. 3. Vitamin E Fact Book, VERIS Research Information Service. 4. Millen B, et al. "Population Nutrient Intake Approaches Dietary Recommendations: 1991 to 1995 Framingham Nutrition Studies." Journal of the American Dietetic Association. 97:742-749 (1997). 5. Vitamin E Fact Book, VERIS Research Information Service. 6. Acuff, RV, et al. "Transport of Deuterium-Labeled Tocopherols During Pregnancy." American Journal of Clinical Nutrition. 67:459-64 (1998). 7. Kiyose C, et al. "Biodiscrimination of Alpha-Tocopherol Sterioisomers in Humans after Oral Administration." American Journal of Clinical Nutrition. 65:785-789 (1997). 8. Albanes, D. Journal of the National Cancer Institute. March 18, 1998. 9. Hossain, S., et al. "Single-Dose Vitamin A Treatment In Acute Shigellosis in Bangladeshi Children: Randomised Double-Blind Controlled Trial." British Medical Journal. 316: 422-426 (1998). 10. Plotnick, G. "Effect of Antioxidant Vitamins on the Transient Impairment of Endothelium-Dependent Brachial Artery Vasoactivity Following a Single High-Fat Meal." Journal of the American Medical Association. 278: 1682-1686 (1997). 11. Chylack, L. Opthalmology. June 1998.