Alpha-tocopherol: The Great Protector
by Hans R. Larsen, MSc ChE
Research carried out in universities, hospitals, and laboratories around the world provides conclusive evidence that alpha-tocopherol, better known as vitamin E, is absolutely crucial to human health. Moreover, it has been clearly established that the amount of vitamin E present in even the most carefully selected diet is totally inadequate to meet the requirement for this vitamin. The recognition that vitamin E supplementation is essential is a radical departure from the previous stand of the medical/scientific community that very little, perhaps 10-30 milligram/day, of vitamin E is needed and that this amount can be supplied through the normal diet.
Vitamin E, however, is not merely a vitamin. The most active component of the vitamin E complex is alpha-tocopherol and this organic substance is the most powerful antioxidant in the lipid (fat) phase of the human body (1,2). So alpha-tocopherol has two functions: it acts as a vitamin (vitamin E) and it acts as an essential antioxidant. It is this function as an antioxidant and its crucial importance which the mainstream scientific community has so belatedly come to realize. Vitamin E cannot be synthesized by the body and must therefore be supplied in the diet or through supplementation. It is only stored in the body for a relatively short time and must be replenished on a regular basis. Unlike the other fat-soluble vitamins, A,D, and K, which are stored in the liver, vitamin E is stored throughout the body in the lipid phase. This fact is of crucial importance in the utilization of alpha-tocopherol to modify metabolic reactions.
Human metabolism is aerobic, that is, it depends on oxygen for sustenance. This has many advantages, but also creates some problems. One of the very major problems is that oxygen has a pronounced tendency to create free radicals - dangerous and highly reactive molecules which are now recognized as being the culprits in a large array of debilitating and deadly diseases.Antioxidants have long been used to prevent and break up free-radical induced chain reactions and are used extensively for that purpose in plastics, rubbers, gasoline, motor oils, and indeed in many, many foodstuffs. As a matter of fact, unsaturated fatty acids occuring in nature almost always contains alpha-tocopherol which protects them from going rancid. In the body, alpha-tocopherol acts very effectively to deactivate free radicals and stops chain reactions before they can run away (1). In contrast to the action of alpha-tocopherol as a vitamin it is actually consumed, sometimes quite extensively, in its role as antioxidant.
The critical role of alpha-tocopherol in protecting against free-radical reactions becomes apparent when considering the vast number of diseases and conditions thought to be caused by these reactions (3,4). Among them are:
Aging is thought to be caused by a decline in the functioning of the immune system as well as by lipid peroxidation leading to undesirable crosslinking and damage to DNA (3). Daily supplementation with vitamins E and C has been shown to lower lipid peroxide concentration in humans (5). Daily supplementation with vitamin E (400 IU/day) was also shown to increase the T-cell mediated immune responses in healthy, elderly people (6).
Recent studies have shown that a low vitamin E concentration in human blood is associated with an overall increased risk for many cancers including breast and lung cancer (7,8,9). There is definite proof that alpha-tocopherol prevents the formation of cancer-promoting nitrosamines in the stomach (5,8). There is also some indication that an increased intake of vitamin E by smokers (experimental dosage: 1000 mg/day of alpha-tocopheryl acetate) can decrease their risk of developing cancer and heart disease (10).
Atherosclerosis is a common form of heart disease. It is characterized by fatty deposits on the walls of the arteries. Cholesterol and low density lipoproteins (LDP) are known to be heavily implicated in the build-up of the fatty deposits. Recent research has confirmed that high blood levels of LDP's accelerate atherosclerosis. It has also been shown that the LDP's are oxidized before they attach to the artery wall and that this oxidation can be slowed down by the use of antioxidants (11,12).
Alpha-tocopherol has been shown to improve the capacity of the blood to carry oxygen, to prevent and dissolve blood clots and is effective in preventing scar formation (13,14). Other research confirmed that daily supplementation with 400 IU of vitamin E results in a significant reduction in blood platelet adhesion in healthy adults (5). Vitamin E has also been found effective in treating varicose veins and thrombophlebitis (14).
Animal studies have shown that alpha-tocopherol can alleviate arthritis symptoms (15). Studies involving humans suffering from osteoarthritis have shown that supplementatiom with vitamin E is effective in relieving pain associated with this disease (15).
Cataracts are a very major health problem in North America. It is estimated that 45% of men and 48% of women over 75 suffer from cataracts. The disease is caused by long term accumulation of free radical damage. A recent study suggests that the risk of getting cataracts may be reduced by more than 50% through supplementation with vitamins C and E (600 and 400 IU/day respectively) (16).
The list of known benefits of alpha-tocopherol in the fight against free-radical induced diseases goes on and on. The evidence is overwhelming that vitamin E is an extremely critical factor in human health. However, it is equally clear that a normal or even carefully selected diet is totally inadequate to provide the needed quantities of the vitamin/antioxidant.
Nutrition-oriented medical doctors are reaching a consensus as to how much alpha-tocopherol is required for a healthy person eating an average diet. The magic number is 400 IU/day which is considered a basic amount (17,18). The optimum intake for an individual depends on many factors including the intake of polyunsaturated fatty acids and the degree of exposure to air pollution and toxic chemicals. Higher dosages may be indicated for women suffering from premenstrual or menopausal problems, for smokers, for people engaging in heavy, out-door exercise, and for people having a family history of cancer (18). Interestingly enough, the intake of fish oils or a large consumption of fish has been shown to increase the requirement for vitamin E quite significantly (19).
Large, well-controlled studies of vitamin E supplementation have shown the vitamin to be non-toxic in intakes as high as 3200 IU/day (20). However, most researchers caution against daily intakes higher than 800-1200 IU/day for extended periods (13,17,18). It is also recommended that the progression to a daily dose of 400 IU be gradual as should any decrease in intake.
There are some cases in which high dosages (more than 30 IU/day) of vitamin E are contraindicated. Medical advice concerning dosage should be sought by individuals having high blood pressure, those taking anticoagulant drugs (Coumadin, warfarin) or having a tendency to prolonged bleeding, those having a vitamin K deficiency and those suffering from rheumatic heart disease, an overactive thyroid, or diabetes (13,18).
Inorganic iron (ferrous sulphate) destroys vitamin E and birth control pills deactivate it to some degree. So vitamin E should be taken with the main meal (to optimize absorption) and at least six hours before or after taking an iron supplement or a multivitamin/mineral tablet or a birth control pill.
Natural vitamin E comes in two forms: d-alpha-tocopherol (100 mg=149 IU) and d-alpha-tocopheryl acetate (100 mg=136 IU). The "d" designation in front of the "alpha" indicates that the products are derived from natural sources such as vegetable oils or wheat germ. A prefix of "dl", such as in dl-alpha-tocopherol, shows that the vitamin has been synthesized from a petroleum base. Recent research has shown d-alpha-tocopherol and d-alpha-tocopheryl acetate to be equally effective on an International Unit basis (21). Synthetic alpha-tocopherol acetate however, has been found to be considerably less effective than its natural equivalent in raising the blood plasma level of vitamin E and in preventing peroxide hemolysis even when ingested at equivalent IU levels (22).
Vitamin E is quite clearly a prime example of a vitamin/antioxidant which is present in the diet in an amount insufficient to sustain health. To obtain a daily dosage of vitamin E equivalent to 400 IU it would be necessary to consume 200 cups of brown rice, 10 cups of almonds, 80 cups of cooked spinach, or 12 tablespoonfuls of unrefined, fresh wheat germ oil - clearly not a viable alternative.
Perhaps the most telling evidence of the metamorphosis of vitamin E from ugly duckling to reigning swan of nutrition can be found in the fact that an eminent scientist who in 1974 supported the contention that an alpha-tocopherol intake of 10-30 mg/day would be adequate for an adult publicly stated in 1991 that he was himself taking 400 IU of vitamin E every second day (22,23). To quote: "... The knowledge that undesirable products of lipid peroxidation in human tissues can be decreased by taking vitamin E have persuaded me to personally take a 269 mg supplement of d-alpha-tocopherol every other day (23)."