(See also Overview of Vitamins.)
Vitamin E (tocopherol) is an antioxidant: It protects cells against damage by free radicals, which are by-products of normal cell activity and which participate in chemical reactions within cells. Some of these reactions can be harmful.
Many people take vitamin E supplements to help prevent certain disorders. Vitamin E supplements do not protect against heart and blood vessel disorders. There is no convincing evidence that vitamin E, even in high doses, slows the progression of Alzheimer disease. Whether vitamin E supplements protect against tardive dyskinesia (repetitive involuntary movements of the mouth, tongue, arms, or legs—a side effect of antipsychotic drugs) and whether they increase or decrease the risk of prostate cancer is controversial.
Vitamin E, like vitamins A, D, and K, is a fat-soluble vitamin, which dissolves in fat and is best absorbed when eaten with some fat. Good sources of vitamin E include vegetable oils, nuts, seeds, green leafy vegetables, and wheat germ.
The deficiency may cause impaired reflexes and coordination, difficulty walking, and weak muscles.
Premature infants with the deficiency may develop a serious form of anemia.
The diagnosis is based on symptoms and results of a physical examination.
Taking vitamin E supplements corrects the deficiency.
Newborns have a relatively low reserve of vitamin E because only small amounts of vitamin E cross the placenta. Thus, newborns, particularly premature newborns, are at increased risk of vitamin E deficiency. However, with age, risk decreases because infants usually get enough vitamin E in breast milk or in commercial formulas. Adults can store large amounts of vitamin E in fat tissue, making the deficiency less likely.
A very low fat diet lacks vitamin E because vegetable oils are the main source of this vitamin and because vitamin E is best absorbed when eaten with some fat. Disorders that impair fat absorption (such as certain liver or gallbladder disorders, pancreatitis, and cystic fibrosis) can also reduce the absorption of vitamin E and increase the risk of vitamin E deficiency.
In the United States and other developed countries, vitamin E deficiency is rare among older children and adults and is usually due to
A disorder that impairs fat absorption (malabsorption disorder)
In developing countries, the most common cause of vitamin E deficiency is
Symptoms may include slow reflexes, difficulty walking, loss of coordination, loss of position sense (knowing where the limbs are without looking at them), and muscle weakness. In children, the eyelids may droop, and they may have difficulty moving their eyes.
In adults with vitamin E deficiency due to a malabsorption disorder, these symptoms rarely develop because adults store large amounts of vitamin E in fat (adipose) tissue.
Vitamin E deficiency can cause a form of anemia in which red blood cells rupture (hemolytic anemia). Premature infants who have a vitamin E deficiency are at risk of this serious disorder. In premature infants, bleeding (hemorrhage) may occur within the brain, and blood vessels in the eyes may grow abnormally (a disorder called retinopathy of prematurity). Affected newborns also have weak muscles.
Treatment of vitamin E deficiency involves taking vitamin E supplements by mouth.
Premature newborns may be given supplements to prevent disorders from developing. Most full-term newborns do not need supplements because they get enough vitamin E in breast milk or commercial formulas.
Many adults take relatively large amounts of vitamin E for months to years without any apparent harm. However, high doses of vitamin E may increase the risk of bleeding (including bleeding within the brain, causing stroke), particularly for adults who are also taking an anticoagulant (especially warfarin). Occasionally, adults who take very high doses develop muscle weakness, fatigue, nausea, and diarrhea.
The diagnosis of vitamin E toxicity is based on the person’s history of using vitamin E supplements and symptoms.
Treatment of vitamin E toxicity involves stopping vitamin E supplements. If necessary, vitamin K, which helps blood clot, is given to stop bleeding.