Vitamin E deficiency: a risk factor in human disease?

Oxidative stress is suspected to intervene in certain chronic diseases. Muc h research has been devoted to the relationship between vitamin E, a major lipid-soluble antioxidant, and certain widespread diseases. Experimental an d epidemiological proof supports a protective effect of vitamin E in a numb er of pathological processes such as coronary heart disease, cancer, catara ct, diabetes mellitus, and Alzheimer disease. Randomized clinical trials ha ve not confirmed a beneficial effect of vitamin E supplementation on the pr ogression of these diseases. Certain methodological biases could however ha ve affected these studies, explaining conflicting results. These biases inc lude inaccuracy or vitamin E intake estimates and changes in eating habits during the course of the survey. An insufficient supplementation period usi ng an insufficient dose and inclusion of aged and high-risk patients are th e main limitations of the reported clinical trials. Large scale randomized clinical trials including healthy and low-risk subje cts, along with prolonged administration of high-dose natural vitamin E, as sociated with synergetic compounds, and testing on morphological or biologi cal features, will allow a better understanding of the relationship between vitamin E and chronic diseases.