get the d-alpha-tocopherol
I suggest the natural d-alpha-tocopherol, not the synthetic dl form, is best. Considering that the natural form has been shown to be up to 50 percent more potent than dl-alpha-tocopherol (a synthetic version), it might be an obvious choice, so read the label closely on the multivitamin or antioxidant formula.
Anywhere from 400 to 1,200 IU's, taken daily, is a typical range. The more active the person, the greater amount the body may need.