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What is Vitamin E?
Vitamin E is a fat-soluble vitamin that exists in eight different forms. Each form has its own biological activity, which is the measure of potency or functional use in the body. Alpha-tocopherol (α-tocopherol) is the name of the most active form of vitamin E in humans. It is also a powerful biological antioxidant. Vitamin E in supplements is usually sold as alpha-tocopheryl acetate, a form of alpha-tocopherol that protects its ability to function as an antioxidant. The synthetic form is labeled "D, L" while the natural form is labeled "D". The synthetic form is only half as active as the natural form.
Antioxidants such as vitamin E act to protect your cells against the effects of free radicals, which are potentially damaging by-products of energy metabolism. Free radicals can damage cells and may contribute to the development of cardiovascular disease and cancer. Studies are underway to determine whether vitamin E, through its ability to limit production of free radicals, might help prevent or delay the development of those chronic diseases. Vitamin E has also been shown to play a role in immune function, in DNA repair, and other metabolic processes.
Vitamin E Resources
Vegetable oils, nuts, green leafy vegetables, and fortified cereals are common food sources of vitamin E.
Who is at risk for vitamin E deficiency?
Blood levels of vitamin E may also be decreased with zinc deficiency. Vitamin E deficiency is usually characterized by neurological problems associated with nerve degeneration in hands and feet. These symptoms are also associated with other medical conditions. A physician can determine if they are the result of a vitamin E deficiency or are from another cause.
Who may need extra vitamin E to prevent a deficiency?
People who cannot absorb fat often pass greasy stools or have chronic diarrhea. People with an inability to secrete bile, a substance that helps fat digestion, may need a special water-soluble form of vitamin E.
Abetalipoproteinemia is a rare inherited disorder of fat metabolism that results in poor absorption of dietary fat and vitamin E. The vitamin E deficiency associated with this disease causes problems such as poor transmission of nerve impulses, muscle weakness, and degeneration of the retina that can cause blindness. Individuals with abetalipoproteinemia may be prescribed special vitamin E supplements by a physician to treat this disorder.
Ataxia and vitamin E deficiency (AVED) is also a rare inherited disorder. It is caused by a genetic defect in a liver protein that is responsible for maintaining normal alpha-tocopherol concentrations in the blood. These individuals have such severe vitamin E deficiency that without supplements they are unable to walk (ataxia).
Very low birth weight infants may be deficient in vitamin E. Necrotizing enterocolitits, a condition sometimes seen in very low birth weight infants that is characterized by inflammation of the lining of the intestines, may lead to a vitamin E deficiency. These infants are usually under the care of a neonatologist, a pediatrician specializing in the care of newborns who evaluates and treats the exact nutritional needs of premature infants.
What is the health risk of too much vitamin E?
Most studies of the safety of vitamin E supplementation have lasted for several months or less, so there is little evidence for the long-term safety of vitamin E supplementation.
The Food and Nutrition Board of the Institute of Medicine has set an upper tolerable intake level (UL) for vitamin E at 1,000 mg (1,500 IU) for any form of supplementary alpha-tocopherol per day. Based for the most part on the result of animal studies, the Board decided that because vitamin E can act as an anticoagulant and may increase the risk of bleeding problems this UL is the highest dose unlikely to result in bleeding problems.
Vitamin E is a fat-soluble vitamin that exists in eight different forms. Each form has its own biological activity, which is the measure of potency or functional use in the body. Alpha-tocopherol (α-tocopherol) is the name of the most active form of vitamin E in humans. It is also a powerful biological antioxidant. Vitamin E in supplements is usually sold as alpha-tocopheryl acetate, a form of alpha-tocopherol that protects its ability to function as an antioxidant. The synthetic form is labeled "D, L" while the natural form is labeled "D". The synthetic form is only half as active as the natural form.
Antioxidants such as vitamin E act to protect your cells against the effects of free radicals, which are potentially damaging by-products of energy metabolism. Free radicals can damage cells and may contribute to the development of cardiovascular disease and cancer. Studies are underway to determine whether vitamin E, through its ability to limit production of free radicals, might help prevent or delay the development of those chronic diseases. Vitamin E has also been shown to play a role in immune function, in DNA repair, and other metabolic processes.Vitamin E Resources
Vegetable oils, nuts, green leafy vegetables, and fortified cereals are common food sources of vitamin E.
Who is at risk for vitamin E deficiency?
Vitamin E deficiency is rare in humans. There are three specific situations when a vitamin E deficiency is likely to occur.
- Persons who cannot absorb dietary fat due to an inability to secrete bile or with rare disorders of fat metabolism are at risk of vitamin E deficiency.
- Individuals with rare genetic abnormalities in the alpha-tocopherol transfer protein are at risk of vitamin E deficiency.
- Premature, very low birth weight infants (birth weights less than 1500 grams, or 3 pounds, 4 ounces) are at risk of vitamin E deficiency.
Blood levels of vitamin E may also be decreased with zinc deficiency. Vitamin E deficiency is usually characterized by neurological problems associated with nerve degeneration in hands and feet. These symptoms are also associated with other medical conditions. A physician can determine if they are the result of a vitamin E deficiency or are from another cause.
Who may need extra vitamin E to prevent a deficiency?
Individuals who cannot absorb fat require a vitamin E supplement because some dietary fat is needed for the absorption of vitamin E from the gastrointestinal tract. Intestinal disorders that often result in malabsorption of vitamin E and may require vitamin E supplementation include:
- Crohn's Disease is an inflammatory bowel disease that affects the small intestines. People with Crohn's disease often experience diarrhea and nutrient malabsorption.
- Cystic Fibrosis is an inherited disease that affects the lungs, gastrointestinal tract, pancreas, and liver. Cystic fibrosis can interfere with normal digestion and absorption of nutrients, especially of fat soluble vitamins including vitamin E.
People who cannot absorb fat often pass greasy stools or have chronic diarrhea. People with an inability to secrete bile, a substance that helps fat digestion, may need a special water-soluble form of vitamin E.
Abetalipoproteinemia is a rare inherited disorder of fat metabolism that results in poor absorption of dietary fat and vitamin E. The vitamin E deficiency associated with this disease causes problems such as poor transmission of nerve impulses, muscle weakness, and degeneration of the retina that can cause blindness. Individuals with abetalipoproteinemia may be prescribed special vitamin E supplements by a physician to treat this disorder.
Ataxia and vitamin E deficiency (AVED) is also a rare inherited disorder. It is caused by a genetic defect in a liver protein that is responsible for maintaining normal alpha-tocopherol concentrations in the blood. These individuals have such severe vitamin E deficiency that without supplements they are unable to walk (ataxia).
Very low birth weight infants may be deficient in vitamin E. Necrotizing enterocolitits, a condition sometimes seen in very low birth weight infants that is characterized by inflammation of the lining of the intestines, may lead to a vitamin E deficiency. These infants are usually under the care of a neonatologist, a pediatrician specializing in the care of newborns who evaluates and treats the exact nutritional needs of premature infants.
What is the health risk of too much vitamin E?
Most studies of the safety of vitamin E supplementation have lasted for several months or less, so there is little evidence for the long-term safety of vitamin E supplementation.
The Food and Nutrition Board of the Institute of Medicine has set an upper tolerable intake level (UL) for vitamin E at 1,000 mg (1,500 IU) for any form of supplementary alpha-tocopherol per day. Based for the most part on the result of animal studies, the Board decided that because vitamin E can act as an anticoagulant and may increase the risk of bleeding problems this UL is the highest dose unlikely to result in bleeding problems.
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