Vitamin E is a fat-soluble vitamin that has eight different chemical forms. The most biologically active of these is alpha tocopherol. Vitamin E is a component of all cell membranes and of some other organelles such as mitochondria. It acts in membranes of red blood cells to keep the cells flexible as they pass through blood vessels. Vitamin E also protects all cells from free radicals that may damage them. Cells make some free radicals as by-products of metabolism and others are components of environmental pollutants such as smoke.
Daily Requirement
Package labels of prepared foods or supplements usually list Vitamin E in International Units. The minimum amount of vitamin E that a person needs daily depends on age, according to the Office of Dietary Supplements of the National Institutes of Health. Infants and children under 3 need between 6 and 9 IU daily. The requirement increases for children aged 4 through 13 to 10 to 16 IU each day. Older children, teenagers and adults should consume about 22 IU daily. The daily minimum requirement is slightly higher, about 28 IU, for breastfeeding women.
Natural Sources
Vitamin E is a natural part of many foods. The best sources are vegetable oils such as wheat germ, sunflower and safflower oils. Vitamin E also is a component of corn and soybean oils. Nuts such as peanuts and almonds and seeds, including sunflower seeds, also are good sources. Some vegetables such as spinach and broccoli also provide modest amounts of vitamin E.
Vitamin E Supplements
Most over-the-counter vitamin and mineral supplements contain vitamin E. Once-daily vitamin pills usually provide about 30 IU units of vitamin E. Supplements that contain only vitamin E are available in a range of potency, from 100 to 1,000 IU per pill. Natural vitamin E is d-alpha-tocopherol while synthetic vitamin E is dl-alpha-tocopherol. According to the Office of Dietary Supplements, the natural form is more potent, with 100 IU of natural vitamin E equivalent to about 150 IU of the synthetic type.
Health Benefits
According to the Harvard School of Public Health, current research suggests that supplementing vitamin E from food with an additional 200 IUs daily is reasonable. However, the possible health benefits of vitamin E supplements are not fully known. Modest doses of vitamin E did not protect against heart disease in several studies, although higher doses were not evaluated. The School of Public Health website also reports that long-term use of vitamin E may reduce the risk of bladder cancer, but notes that studies of other cancers have been inconclusive. Vitamin E in combination with other antioxidants may have some benefit in helping older people avoid age-related macular degeneration or other vision problems.
Precautions
The highest safe level of vitamin E intake is 1,500 IU of natural vitamin E daily and less for children, according to the Office of Dietary Supplements. Vitamin E has a natural anti-clotting action so higher doses carry a risk of bleeding. Vitamin E should not be taken with certain medicines such as anticoagulant drugs, and it may also interfere with the effectiveness of chemotherapy medicines or other drugs. Anyone considering taking vitamin E supplements should first consult a doctor to determine if this is appropriate.
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