CHICAGO, ILLINOIS. Vitamin E from food has been found to reduce the risk of Alzheimer's disease, most likely due to its antioxidant effect on free radicals. Free radicals may contribute to the pathological processes in Alzheimer's, and evidence shows that levels of vitamin E are low in the cerebrospinal fluid of patients with this disorder. However, doubts exist over whether vitamin E from supplements can produce the same beneficial effect. Vitamin E is primarily found in vegetable and seed oils and comprises four different tocopherols (alpha, beta, gamma and delta) and four tocotrienols. Supplements usually only contain alpha- tocopherol.
Researchers from Rush University Medical Center investigated the effects of each form of dietary tocopherol on Alzheimer's disease and cognitive decline. Study participants came from the ongoing Chicago Health and Aging Project and were all over 64 years old and living in the community. They were followed for six years during which they were evaluated for Alzheimer's disease and periodically completed a food- frequency questionnaire to determine vitamin E intake.
As previously found, tocopherol intake from food reduced incidence of Alzheimer's disease. In an analysis of 1,041 participants, vitamin E reduced four-year risk by 26 per cent, per increase of 5 mg per day. It was also linked to better cognitive performance over six years in a larger analysis of 3,718 participants. Both alpha- and gamma-tocopherol were independently linked to slower cognitive decline, with a 34 per cent and 40 per cent reduction, respectively, for an increase of 5 mg intake per day. Once intake of other forms of dietary fat was taken into account, the protective affect against cognitive decline was even stronger. The beneficial effect was only seen in those without the APOE-e4 allele - an established risk factor for Alzheimer's disease.
The researchers believe that the vitamin E protection could be due to combined intake of the different forms
which may act in synergy. They conclude that other forms of tocopherol than alpha-tocopherol may play a
protective role against Alzheimer's disease.