Vitamin E

DESCRIPTION

Vitamin E occurs as eight compounds in nature: alpha, beta, delta and gamma tocopherol and tocotrienols. On supplement labels vitamin E refers to "d-alpha tocopherol/tocotrienol." equivalent. The synthetic form of vitamin E is "dl-alpha tocopherol" and is a less active form. Vitamin E is measured in mg and i.u. where:
1 mg = 1.49 i.u.

STABILITY

Commercial food processing reduces the vitamin E content of foods as does freezing and deep-frying. Solvent extraction of vegetable oils also destroys vitamin E.

N.B. Acetate and succinate are more stable forms of vitamin E often used in supplement manufacture.

FUNCTIONS

Vitamin E is a very important antioxidant. Its properties are vital in the membranes of tissues which have a high concentration of polyunsaturated fats (PUFAs), such as in the brain, nervous system and lungs.

Vitamin E helps protect PUFAs and other fatty substances such as cholesterol from oxidation caused by free radicals, the highly reactive by-products of metabolism which also arise from environmental sources.

As an antioxidant nutrient, vitamin E helps to prevent conversion of nitrites in smoked, pickled and cured foods to nitrosamines (possible carcinogens) in the stomach. As an antioxidant, vitamin E works closely with Vitamin C .

Vitamin E has a very powerful antioxidant effect in the body - protecting the lipids in cell walls particularly. Lipids are particularly susceptible to oxidation by free radicals (highly reactive by-products of metabolism also arising from environmental sources).

In its capacity as an antioxidant, vitamin E can act to reduce the oxygen requirement of muscles and thereby increase exercise capacity. It also helps healing and is protective against Atherosclerosis and thrombosis.

Vitamin E also has an important neurological role and prevents degeneration of the nerves and muscles.
Vitamin E may also play an important role in stimulating the immune response (1).

DEFICIENCY

Deficiency of vitamin E does not lead to any specific disease in the short term, but chronic insufficiency of vitamin E is thought to be a contributory factor in cancer and heart disease.

In children, fat malabsorption can lead to a deficiency of vitamin E characterised by abnormal red blood cell development.

REQUIREMENTS

Upper safe level for daily supplementation = 800mg (1200i.u.)

Recommended Daily Allowance = 10mg

SUPPLEMENTAL USES

Vitamin E supplements are advised in individuals who have fat malabsorption problems.

To date, these are some of the conditions that vitamin E supplements may help prevent:

Heart conditions (2)
Circulatory disorders(3)
Fibrocystic breast disease (4)
Blood platelet aggregation (e.g. in susceptible women on the contraceptive pill) (5)
Vitamin E requirement increases when the intake of polyunsaturated fats (PUFAs) increases.
Extra vitamin E has benefited smokers. Free radical damage in the lungs increases the requirement for this vitamin.
Vitamin E may also be used as a nutritional therapy in the following conditions:

Pre-menstrual syndrome (6) (especially with Evening Primrose Oil )
Post-operative Wound healing (7)
Poor circulation (3), Varicose veins, etc.
Alzheimer’s disease (8)
Coronary Heart Disease:
Recent studies indicate that supplementation with 400-800i.u. of vitamin E can reduce the incidents of non-fatal heart attacks by preventing lipid oxidation, thereby modifying the size of the coronary atherosclerotic plaque (9).

Parkinson’s Disease:
Studies suggest that high intakes of vitamin E may slow down the progression of Parkinson’s disease and reduce the severity of other neurological disorders (1).

SAFETY

Levels over about 800mg vitamin E (d-alpha tocopherol) have occasionally been associated with such symptoms as Fatigue, nausea, mild gastrointestinal problems, palpitations and transient blood pressure increase. Such symptoms are reversible.

INTERACTIONS AND CONTRA-INDICATIONS

Interactions have been reported between vitamin E and a range of drugs, and anyone taking medication should consult their general practitioner before using vitamin E supplements.

Anti-coagulant Drugs:
Vitamin E supplements should only be taken under medical supervision by people taking anticoagulant drugs such as aspririn, since bith have a blood thinning effect and there are reports that the combination has resulted in increased bleeding.

Diabetes and Hypothyroidism:
High levels of vitamin E are best avoided by those suffering from these conditions.

Selenium:
Vitamin E activity is increased by Selenium and vice versa.
This is known as a synergistic action.

FOOD SOURCES

Food (mg/100g)
Wheatgerm oil 178
Safflower oil 97
Sunflower seeds, raw 74
Sunflower oil 73
Almonds 37
Mayonnaise 19
Wheatgerm 17
Margarine, hard 16
Peanut butter 9
Soybean oil 8
Butter 3
Asparagus 2.7
Spinach 2.7
Broccoli 0.7
Bananas 0.3
Strawberries 0.3

REFERENCES

1. "Human Nutrition and Dietetics", J S Garrow & W P T James, Churchill Livingstone, 1996.
2. Kwiterovich PO Jr. The effect of dietary fat, Antioxidants , and pro-oxidants on blood lipids, lipoproteins, and Atherosclerosis. J Am Diet Assoc, 97;7 suppl:S31-41, 1997.
3. "Martindale The Extra Pharmacopoeia", J Reynolds, The Pharmaceutical Press, 29th Ed, 1989.
4. London RS et al. Endocrine parameters and alpha-tocopherol therapy of patients with mammary dysplasia. Caner Res, 41:3811-3813, 1981.
5. Renaud S et al. Influence of vitamin E administration on platelet functions in hormonal contraceptive users. Contraception, 36:347-358, 1987.
6. London RS et al. Efficacy of alpha-tocopherol in the treatment of the premenstrual syndrome. J Reprod Med, 32;6:400-404, 1987.
7. Int J Dermatol, 1995,34;7:506-509.
8. Sano et al. A controlled clinical trial of Selegiline, Alpha-tocopherol or both as treatment for Alzheimer's Disease. New England J Med, 336;17:1216-1222, 1997.
9. Stephens NG et al. Randomised controlled trial of vitamin E in patients with coronary disease: Cambridge Heart Antioxidant and Study (CHAOS). The Lancet, 347;9004:781-786, 1996.