Vitamin E

Biological antioxidant that protects cells from free radicals.

A group of 8 related fat soluble compounds four of which are tocopherols and four are tocotrienols, exhibiting vitamin E biologic activity.

Vitamin E: a set of eight related tocopherols and tocotrienols, which are fat-soluble vitamins with antioxidant properties.

Alpha tocopherol is the most active vitamin E and the most widely available.

The major lipid soluble antioxidant that donates electrons and neutralizes free radicals as a defense to oxidative stress.

Has a role in termination of free radical generated lipid peroxidation chain reactions, primarily in cellular and sub cellular membranes rich in polyunsaturated lipids.

Present in vegetable oils, nuts, fortified cereals and leafy vegetables.

Widely available in foods and it is unlikely to be insufficient secondary to dietary inadequacy.

Asorption requires normal biliary tree and pancreatic function.

After absorption it is transported as chylomicrons in the blood and rapidly equilibrates with plasma lipoproteins.

Accumulates throughout the body and mainly in fat depots, liver and muscle.

400 IU administered daily for four to six years has no beneficial effects on cardiovascular outcomes in a high-risk population of patients greater than 55 years of age or older.

People on vitamin E are more likely to have congestive heart failure.

Women’s Health Initiative found that 38,876 women using 600 IU of vitamin E vs placebo followed for an average of 10 years had no benefits preventing cardiovascular events or death.

Has no beneficial effects on the incidence or duration of lower respiratory infections in elderly nursing home patients.

Supplementation in elderly nursing home patients resulted in significantly fewer common colds and a 20% lower risk of acquiring a cold than placebo.

Supplementation does not reduce the incidence of cancer.

In doses greater than 400 IU/d associated with increased mortality risk.

Alpha-tocopherol, a form of vitamin E, provided no benefit in reducing the risk of a second primary tumor in survivors of Stage I or Stage II head and neck cancer.

ATBC trial of 50 mg/d associated with a lowered incidence of prostate cancer but no effect on lung or colon cancer.

In the SELECT (Selenium and Vitamin E Cancer Prevention Trial) trial dietary supplementation with vitamin E significantly increased the risk of prostate cancer, 17%, among healthy men (Klein E et al).

Low levels in community living elderly men and women associated with subsequent physical decline.

The nervous system is particularly vulnerable to vitamin E deficiency as the long axons have a large membrane surface.

Vitamin E deficiency typically results in eye problems with degeneration of the spinocerebellar and dorsal column tracts.

Red blood cells are vulnerable to vitamin E deficiency because of their risk for oxidative injury imposed by super oxide radical generation during oxygenation of hemoglobin.

Deficiency from diet is uncommon and occurs almost exclusively with fat malabsorption, associated with cholestasis, cystic fibrosis and small bowel disease, infants with low birth weight and liver immaturity, and abetalipoproteinemia.

Abetalipoproteinemia is a rare autonomic recessive disorder with abnormal transport of Vitamin E as the apoprotein B component of chylomicrons, LDLs, VLDLs is not synthesized.

In a phase III trial of 247 adults with nonalcoholic steatohepatits and without diabetes were randomized to pioglitazone, vitamin E or placebo:vitamin E compared to placebo was associated with a significantly higher rate of improvement of nonalcoholic steatohepatitis 43% vs 19%, and pioglitazone was not beneficial compared to placebo.

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