A powerful antioxidant. The main role of vitamin E is its antioxidant activity, and protecting structures such as fats (that make up an integral part of the cell membrane) from the negative changes caused by free radicals. Proteins and DNA are also frequent targets of free radicals, and vitamin E also protects them. It is fat soluble and it is no surprise that it is found in the highest quantities in foods rich in healthy fats, such as nuts, seeds and vegetable oils.