Monday, August 24, 2009

Vitamin E

Vitamin E comes in eight different forms with alpha-tocopherol being the most widely studied form. Antioxidant is a word commonly associated with vitamin E. The antioxidant mechanism involves the vitamin giving up one of its electrons to a free radical, which is an electron short of stability, thereby reducing the free radical’s damaging effects on cellular structure. Vitamin E is also important in the formation of red blood cells and vitamin K absorption.

Antioxidant properties may temper symptoms of mild cognitive impairment and Alzheimer’s disease. As well, low serum levels of vitamin E have been noted in depression (1). Research is still being conducted on whether or not the primary role and biological necessity of vitamin e is indeed its antioxidant property.

A study done in 2005 concluded that the lower levels of vitamin E (alpha-tocopherol) in depressed patients was not a result of poor dietary intake.

A review done in 2008 concluded there was no significant benefit of vitamin E treatment for Alzheimer’s or mild cognitive impairment and that the role of vitamin E in managing cognitive impairment was questionable.

Another study comparing vitamin E with donepezil produced similar results showing no slowing of progression of Alzheimer’s disease.

A study, with no placebo group, showed a combination of vitamins E and C with omega fatty acids decreased the effects of positive and negative symptoms in schizophrenia.

The recommended daily intake of vitamin E is about 400 IU/day and therapeutic values can be up to 1600 IU/day.

Toxicity can occur at very high doses of about 3000 IU/day. However, when vitamin K deficiency is also present, doses of over 1600 IU/day can interfere with normal haematological processes such as bleeding time and clotting (2). Vitamin E supplementation may impair the haematological response to iron in children with iron-deficiency anaemia. As well, high doses of vitamin E may increase cardiovascular risks (3, 4).

Sources of vitamin E include mustard greens, turnip greens, chard, sunflower seeds, almonds, spinach, collard greens, parsley, kale, papaya, olives, bell pepper, brussel sprouts, kiwi, tomato, blueberries, and broccoli.

References: 1, 2, 3, 4

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