Symptoms of deficiency include nerve damage, muscle weakness, poor coordination, involuntary eye movements, red blood cell fragility, anemia and retrolental fibroplasis (eye disease).

Vitamin E is available in many formations, either natural or synthetic. Natural forms of vitamin E are designated as "d-", as in d-a-tocopherol. Synthetic forms are designated as "dl-". The biologically active form of the vitamin is the "d-" form (natural) and it is recommended for supplementation over the "dl-" (synthetic) form. Beta-tocopherol, gamma-tocopherol, and the alpha- and delta-tocotrinols have less than 50% of the biological activity than d-a-tocopherol.

The RDA for vitamin E (d-a-tocopherol) is set at 15 IU/day. The amount of vitamin E required is dependent upon the amount of polyunsaturated fat in the diet. The more polyunsaturated fat in the diet. The more polyunsaturated fat there is in the diet, the greater the risk for oxidative damage, increasing the requirement of vitamin E. Most studies have utilized doses between 200-400 IU/day. Some studies report effective use of vitamin E at doses up to 3000 IU/day over a two year period without observed side effects.