Vitamin E is an important anti-oxidant that interacts with vitamin A to help prevent free radical damage. It is also protects red blood cells and supports the immune system, increasing resistance to infection. Because vitamin E is so plentiful in foods, deficiency is basically absent in the general population (although premature infants may have deficiency). It is found in a wide variety of sources including vegetable oils and margarine, whole grain and cereals, and green leafy vegetables.