Vitamin E (Tocopherol)
Elson M. Haas M.D.
Vitamin E (Tocopherol) is a light yellow oil, a fat-soluble vitamin, that is actually a family of compounds, the tocopherols, found in nature. Alphatoxopherol is the most common and the most active of the seven currently described forms-alpha, beta, gamma, delta, epsilon, and zeta. Specifically, d-alpha tocopherol is the most potent form, more active than the synthetic dl-alpha tocopherol.
Vitamin E was discovered in 1922 with experiments on rats. When fed a purified diet devoid of vitamin E, the rats became infertile. Wheat germ oil added to their diet restored their fertility. Later, the oil-based substance was isolated and called the "antisterility" vitamin. (Tokos and phero are the Greek words for "offspring" and "to bear," so tocopherol literally means "to bear children.") Though there is no clear deficiency disease in humans, vitamin E is well accepted as an essential vitamin. There is some question, however, as to whether vitamin E is needed for fertility. From general public experience, though, it seems to be clear that vitamin E makes a difference to many. The average diet today contains much less natural vitamin E than it did 50 years ago; we will see soon why, and what vitamin E actually does in the body.
Alpha-tocopherol is basically stable in heat and in acids; other forms are lost in heat, with storage or freezing, or when oxidized by exposure to the air. All vitamin E's are slightly unstable in alkali and are readily used up when in contact with polyunsaturated oils or rancid fats and oils, which are protected from oxidative destruction by vitamin E. Frying oils, the processing and milling of foods, the bleaching of flours, and cooking remove much of the vitamin E content of whole foods. During the refinement and purification of vegetable oils, vitamin E is lost; the vitamin E-rich by-products of this process are used to make some of the E used in supplements.
Vitamin E is absorbed from the intestines, along with fat and bile salts, first into the lymph and then into the blood, which carries it to the liver to be used or stored. Vitamin E is not stored in the body as effectively as the other fat-soluble vitamins, A, D, and K. Over half of any excesses may be lost in the feces, but some vitamin E is stored in the fatty tissues and the liver and to a lesser degree in the heart, muscles, testes, uterus, adrenal and pituitary glands, and in the blood. Vitamin E is partially absorbed through the skin when used as an ointment or oil application. Intestinal absorption, however, is reduced somewhat with chlorine, inorganic iron, and mineral oil. Unsaturated oils and estrogen also deplete vitamin E, increasing the body's demand for it.
Vitamin E, as its various tocopherol forms, is found in both plant and animal foods. In general, the animal sources of E are fairly poor, with some being found in butter, egg yolk, milk fat, and liver. The best sources of vitamin E are the vegetable and seed or nut oils. It was first isolated from wheat germ oil, which is still a commonly used, rich source of vitamin E.
The oil component of all grains, seeds, and nuts contain tocopherol. The protective covering or germ part of the grains is what contains the E, and this is lost easily in the milling of flour or in the refinement of grains. For the vitamin E to be preserved, extraction of the oils from nuts and seeds must be done naturally, as by cold pressing, rather than by heat or chemical extraction, used commonly in food processing. Because of these forms of processing, the average American diet has lost many of its natural sources of tocopherols, and intake is commonly very low. The cold-pressed vegetable oils are really the best source of vitamin E, and these are most healthfully used in their raw form in salad dressings and sauces rather than in cooking, since most are polyunsaturated oils, which are adversely affected by heating. With refined or cooked polyunsaturates, more vitamin E is needed to prevent oxidation, which could lead to free radical formation, the invisible, underlying cause of many diseases. Free-radical-induced changes occur at the cellular level, the primary processes leading to many chronic degenerative diseases. The vitamin E content of most foods is related to the content of linoleic and linolenic acids, our most essential fatty acids (see Chapter 4, as well as Vitamin F). Also, the content of active alpha-tocopherol varies among the different foods and oils. Safflower oil is one of the best sources, with about 90 percent of the E being the alpha variety. Corn oil has only about 10 percent alpha-tocopherol. Some other foods that contain significant amounts of vitamin E are soybeans, some margarines and shortenings made from vegetable oils, and a few vegetables, such as uncooked green peas, spinach, asparagus, kale, and cucumber; tomato and celery also have a little.
The primary function of vitamin E is as an antioxidant, which is very important, I believe, in our present-day society with widespread pollution, processed food diets, and chemical exposure. Vitamin E is protective because it helps reduce oxidation of lipid membranes and the unsaturated fatty acids and prevents the breakdown of other nutrients by oxygen. This protective, nutritional antioxidant function is also performed and enhanced by other antioxidants, such as vitamin C, beta-carotene, glutathione (L-cysteine), and the mineral selenium. Oxidation in our body of such substances as the fat molecules, particularly from polyunsaturated fats, and from eating other oxidized fats such as hydrogenated oils and rancid oils, causes the genesis of free radicals, unstable molecules that can lead to cellular and tissue irritation and damage, which leads to chronic inflammation, especially in the vascular lining. Excess free radical formation comes from a variety of chemical reactions in the body and is the biochemical basis of many diseases, such as atherosclerosis, heart disease, hypertension, arthritis, senility, and probably even cancer. A number of experiments have shown that the antioxidant nutrients such as vitamin E can protect the tissues from oxidation and free radicals.
Without vitamin E, cell membranes, active enzyme sites, and DNA are less protected from free radical damage. Oxidation by circulating peroxides and superoxides (two types of free radicals) is also reduced by enzymes such as glutathione peroxidase and superoxide dismutase. As does vitamin E, these antioxidant enzymes also protect, by indirect mechanisms, the polyunsaturated fatty acids and vitamin A from oxidative destruction. Fried foods have more oxidized fat by-products, which increase the requirement for vitamin E, but they do not contain any E. This is partly why they are so dangerous when consumed on a regular basis.
More specifically, vitamin E as an antioxidant helps to stabilize cell membranes and protect the tissues of the skin, eyes, liver, breast, and testes, which are more sensitive to oxidation. It protects the lungs from oxidative damage from environmental substances. And vitamin E helps maintain the biological activity of vitamin A, another very important oil-soluble vitamin. Vitamin E protects the unsaturated fatty acids in the body and prevents the oxidation of some hormones, such as those released from the pituitary and adrenal glands. Free radical formation and oxidation are tied to cancer development, so the family of nutritional antioxidants, including vitamin E, may help in preventing tumor growth. More definitive research is needed in regard to this important function.
In simple terms, vitamin E's key function is to modify and stabilize blood fats so that the blood vessels, heart, and entire body are more protected from free-radical-induced injury. Vitamin E also has some anticlotting (antithrombotic) properties and protects the red blood cells' membranes from oxidative damage. Because it helps heart and muscle cell respiration by improving their functioning with less oxygen, vitamin E may help improve stamina and endurance and reduce cardiovascular disease (CVD) risk, especially in those with already existing CVD. Vitamin E has recently been shown to reduce platelet aggregation and platelet adhesiveness to collagen, even more so than aspirin. These platelet functions are linked to an increased risk of atherosclerosis and cardiovascular disease, especially in high-risk groups. Vitamin E has also been shown to neutralize free radicals generated during surgery, particularly cardiopulmonary bypass surgery. It would also protect against the toxicity of some of the gases used in anesthesia.
Although vitamin E was first discovered as the fertility, or at least the antisterility, nutrient, there is no clear evidence that it enhances fertility if there is not a specific deficiency prior to its use. Many people, especially men, take vitamin E with some claimed success in regard to sexuality and vitality. Much of this effect, however, may be due to the antioxidant function and improved circulation and oxygenation.
There is quite an extensive list of uses for this popular nutrient, most commonly in the middle-aged and older populations. And there are many positive effects. Some of these claims are backed by good research, and more investigation is being done on vitamin E by medical and nutritional scientists. There is hope that the results of this research will enable us to better understand its mechanisms and apply them most effectively to prevent and treat our industrial-age medical conditions.
The antioxidant function that we have discussed gives vitamin E a variety of uses. The protection of cells and tissues against oxidation and injury from unstable molecules, pollution, and fats may also be the basis for the prevention of aging and many chronic diseases. Claims about vitamin E's role in preventing premature aging and promoting longevity are big areas of investigation for vitamin E researchers. These claims are often made and with some good reason. Aging, tissue degeneration, and skin changes may be brought about by the damage that free radicals cause to cells unprotected by antioxidant nutrients in the body. Cancer and heart and vascular disease may also be created in this way, and vitamin E therapy may help reduce the risks of these major illnesses. Decreased blood clotting and increased tissue oxygenation may also help reduce symptoms of heart and vascular limitations, such as angina pectoris, intermittent claudication (leg pain with walking due to insufficiency of blood and oxygen, for which vitamin E has clearly been helpful), and problems of arterial spasm. In both congenital and rheumatic heart diseases, vitamin E may help reduce symptoms caused by impaired tissue oxygenation.
Vitamin E may be of help in the prevention of atherosclerosis. Its antioxidant effect reduces thrombin formation and thus helps decrease blood clotting, and it also appears to minimize platelet (blood-clotting component) aggregation and stickiness, aspects that either generate or perpetuate the atherosclerotic process. Vitamin E was thought to raise HDL ("good") cholesterol levels, especially when they were low; however, recent research suggests it has a very mild, if any, effect in this regard. Vitamin A and E together can help to decrease cholesterol and general fat accumulation. To assist in healing and to minimize clotting, tocopherol is a useful nutrient before and after surgery, but is limited to dosages of 200-300 IUs per day (higher amounts may actually suppress the healing process). Also, pre- and postsurgery, vitamin E neutralizes free radical formation and thus reduces possible problems from that. Recently, this antioxidant effect of vitamin E was shown in cardiopulmonary bypass surgery. In regard to its healing powers, vitamin E is used most commonly both internally and externally to assist in the repair of skin lesions, ulcers, burns, abrasions, and dry skin and to heal and/or diminish the scars caused from injury or surgery. (Vitamin A also appears to work in this regard, possibly even better than E in some instances where skin and tissue healing are needed.) Decreasing scars internally may be important in resolving damage from inflammation of blood vessels and may reduce the potential for clotting and thrombophlebitis. Vitamin E, with the help of vitamins C and P (bioflavonoids), may be useful in preventing progression of varicose veins, more so than treating them once they have occurred.
Vitamin E may be very helpful to women. Research shows relief from menstrual pains, as well as general relief from various menstrual disorders. Many problems of menopause, such as headaches, hot flashes, or vaginal itching due to dryness, may be reduced with the use of supplemental vitamin E. When birth control pills are used, the tocopherols may help protect the body from their possible side effects. Estrogen may decrease the effect of vitamin E, so more is needed when estrogen therapy is used. Vitamin E has been used both topically and orally with some success in the treatment of fibrocystic breast disease, or cystic mastitis, likely due to its protective mechanisms against estrogen, which seems to potentiate this disease.
Vitamin E's antioxidant functions help to protect our cell membranes and lung tissue from pollution, particularly from ozone (O3) and nitrogen dioxide (NO2) in the air. Research in rats clearly showed their ability to tolerate increased ozone levels and to survive much longer with vitamin E. There is also some cardiac protection from smoke and alcohol with vitamin E, and it protects against the cardio-toxic effects of adriamycin, an anticancer drug.
Vitamin E has also been used to enhance immunity in the treatment of viral illness and to reduce the neurologic pain from shingles, a viral infection of the nerves and skin. It is also helpful in preventing eye problems, such as poor vision or cataracts, that may be due to oxidation of fatty tissues and free radical formation leading to areas of inflammatory damage. Headaches may sometimes be helped with tocopherol treatment, depending on the cause. Various kidney and liver diseases and muscular dystrophy have all been treated with vitamin E, though more immediate inflammatory problems, as in bursitis, gout, and arthritis seem to benefit more. Leg cramps and circulatory problems associated with diabetes may be helped with vitamin E treatment. For various skin rashes, including those of lupus erythematosus, vitamin E, usually along with vitamin A, may be of some help.
Deficiency and toxicity: Vitamin E is not stored as readily as are the other fat-soluble vitamins. Excess intake is usually eliminated in the urine and feces, and most doses clear the body within a few days. For these reasons, toxicity from vitamin E use is unlikely. In animal studies, very high amounts of E have been shown to retard growth and decrease muscle tissue, decrease the red blood count, and cause poor bone calcification, though in humans these seem more likely to be signs of E deficiency. High intakes of the vitamin E oil can cause nausea, diarrhea, or flatulence in some people.
Large doses of vitamin E are generally avoided for people with high blood pressure as it has been thought to raise blood pressure, though this has not been easily reproduced experimentally. Usually, though, 400-600 IUs daily (the nonoily, water-dispersible vitamin E succinate may be preferable for patients with hypertension) can provide some antioxidant and circulatory benefits without increasing blood pressure. It is possible that large doses of vitamin E (over 1,200 IUs), may have a mild immune-suppressing effect; smaller doses seem to be immune supportive. There is also some concern about using higher doses of vitamin E in people with rheumatic heart disease and administering it to people undergoing digitalis or anticoagulant therapy, as vitamin E may increase the anticoagulant effects of these medicines. Its effects on blood clotting must be watched carefully in such cases. Vitamin E does not contribute to blood clots or abnormal lipid patterns as is sometimes thought.
Vitamin E deficiency is fairly rare with vague symptoms that are difficult to diagnose, causing some question as to its importance since there is no clear deficiency disease in humans as there is with deficiency of vitamin C or many of the B vitamins. Infertility as an effect of vitamin E deficiency has not been revealed as clearly in humans as it was in the rat study. It is likely that vitamin E deficiency is simply more difficult to diagnose symptomatically because of its wide range of effects on the nervous, reproductive, muscular, and circulatory systems and because other nutrients may mask vitamin E deficiencies. However, biochemically, low levels of vitamin E can be measured in the blood and have been seen in such conditions as acne, anemia, infections, some cancers, periodontal disease, cholesterol gallstones, neuromuscular diseases, and dementias such as Alzheimer's disease.
Deficiencies are more of a concern in premature babies, since there is no maternal-fetal vitamin E transfer; vitamin E depletion may also appear in newborns fed on cow's milk, which contains no vitamin E, instead of breast milk, which does contain some if the mother's diet is healthy. Deficiency is also more likely in adults with gastrointestinal disease, with poor fat digestion and metabolism, or with pancreatic insufficiency.
Iron, especially the inorganic form, depletes vitamin E absorption in the small intestine. The two should not be taken together, as this causes the absorption of both to be diminished. Chlorine, ferric chloride, and rancid oils also deplete or destroy vitamin E.
The first sign of vitamin E deficiency may be loss of red blood cells due to fragility caused by the loss of cell membrane protection. Oxidized polyunsaturated fatty acids may also weaken the red blood cell membranes and cause rupture. The generalized decrease in cell and tissue protection from free radical molecules may lead to abnormal fat deposits in muscles, muscle wasting, and problems in the kidneys and liver because of the circulating dead cells and toxins released. Men may have changes in the testicular tissue with vitamin E deficiency.
With increased oxidation, there is an increased requirement for vitamin E. Vitamin E deficiency may lead to free radical effects on the unsaturated fatty acids, inhibiting their functions in the health of cell membranes and tissues. Pituitary and adrenal function may be lowered, as these glands may suffer from the cumulative effects of oxidation. Degenerative changes produced by deficiency of vitamin E may not be corrected by vitamin E therapy.
There is some question as to whether tocopherol ("to bear children") deficiency reduces the ability to carry pregnancy to term and increases the likelihood of premature birth or causes problems in infants. Is it related to increased heart disease or atherosclerosis or even cancer? Surely, there is a lot more to learn about vitamin E.
- Adult males
- Adult females
The amount of vitamin E required depends upon body size and the amount of polyunsaturated fats in the diet, since vitamin E is needed to protect these fats from oxidation. More is needed when any refined oils, fried foods, or rancid oils are consumed. Supplemental estrogen or estrogen imbalance in women increases the need for vitamin E, as does air pollution. And, as I have mentioned, vitamin E should not be taken with iron, especially inorganic iron, such as ferrous sulfate or the iron added to food products. Selenium, another important antioxidant, however, may increase the potency of vitamin E.
Even though the RDA for vitamin E is really quite low, many people do not consume this in their diet alone.
For the d-alpha tocopheral form of this vitamin, 1 mg. equals 1.49 IUs. The different forms of vitamin E have various potencies, with d-alpha the most active and most prevalent in nature. Vitamin E extraction, purity, and activity also vary. The best forms, in my opinion, are those that contain the natural, unesterified d-alpha tocopherol along with the other (beta, gamma, and delta) naturally occurring tocopherols. This type of E is not easy to find because it is more difficult and costly to produce. Vitamin E oil is taken ideally in the morning before breakfast or at night before bed. It can also be taken after meals containing some fat. Approximately 400-600 IUs is used preventively, whereas for therapeutic effects, an amount between 800-1600 IUs daily is suggested. With therapeutic uses of vitamin E, it is best to start with a low level and gradually increase it. Levels over 1,600 IUs per day are not recommended unless there is close medical supervision.