E
(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.
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.
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 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.
Upper safe level for daily
supplementation = 800mg (1200i.u.)
Recommended Daily Allowance = 10mg
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).
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
Anti-coagulant Drugs:
Vitamin E supplements should only be taken under medical
supervision by people taking these drugs.
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 (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.
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