Receiving the best form of vitamin E is critical in obtaining the health benefits of this essential vitamin. One recent study showed that gamma-tocopherol, (which is the form that is highest in food) may actually be superior to alpha-tocopherol (the type that is found in most supplements) in the prevention of Alzheimer’s disease.
Researchers speculate this may explain the absence of vitamin E protection against Alzheimer's reported in some previous studies with the use of vitamin E supplements. Most of the previous studies have used vitamin E supplements that only contained alpha-tocopherol.
To reach this conclusion, researchers examined whether gamma-tocopherol, alpha-tocopherol equivalents (measure of the relative biologic activity of tocopherols and tocotrienols) or individual tocopherols would protect against Alzheimer’s and cognitive decline over a period of six years.
The study included:
- The administration of four cognitive tests
- Clinical evaluations for Alzheimer’s
- Food-frequency questionnaire for dietary assessment
Results indicated various tocopherol forms, rather than solely alpha-tocopherol, may be important in the vitamin E protective association with Alzheimer’s.
American Journal of Clinical Nutrition February 2005 Vol. 81(2) 508-514
Relation of the tocopherol forms to incident Alzheimer disease and to cognitive change1,2,3
1 From the Rush Institute for Healthy Aging (MCM, DAE, JLB, RSW, and NTA), the Department of Internal Medicine (MCM, DAE, and JLB), the Department of Preventive Medicine (MCM), the Rush Alzheimer's Disease Center (DAE, RSW, and NTA), the Department of Clinical Nutrition (CCT), the Department of Neurological Sciences (RSW and NTA), and the Department of Psychology (RSW and PAS), Rush University Medical Center, Chicago, and the Division of Adult and Community Health, Centers for Disease Control and Prevention, Atlanta (PAS).
Background: High intake of vitamin E from food (tocopherol), but not from supplements (which usually contain 
-tocopherol), is inversely associated with Alzheimer disease.
Objective: We examined whether food intakes of vitamin E, -tocopherol equivalents (a measure of the relative biologic activity of tocopherols and tocotrienols), or individual tocopherols would protect against incident Alzheimer disease and cognitive decline over 6 y in participants of the Chicago Health and Aging Project.
Design: The 1993–2002 study of community residents aged 
65 y included the administration of 4 cognitive tests and clinical evaluations for Alzheimer disease. Dietary assessment was by food-frequency questionnaire.
Results: Tocopherol intake from food was related to the 4-y incidence of Alzheimer disease determined by logistic regression in 1041 participants who were clinically evaluated (n = 162 incident cases) and to change in a global cognitive score determined by mixed models in 3718 participants. Higher intakes of vitamin E (relative risk: 0.74 per 5 mg/d increase; 95% CI: 0.62, 0.88) and -tocopherol equivalents (relative risk: 0.56 per 5 mg/d increase; 95% CI: 0.32, 0.98) were associated with a reduced incidence of Alzheimer disease in separate multiple-adjusted models that included intakes of saturated and trans fats and docosahexaenoic acid. - and 
-Tocopherol had independent associations. In separate mixed models, a slower rate of cognitive decline was associated with intakes of vitamin E, -tocopherol equivalents, and - and -tocopherols.
Conclusion: The results suggest that various tocopherol forms rather than - tocopherol alone may be important in the vitamin E protective association with Alzheimer disease.