Vitamin E deficiency
Vitamin E deficiency is a very rare problem that results in damage to nerves.When vitamin E deficiency does occur, it strikes people with diseases that prevent the absorption of dietary fats and fat-soluble nutrients. Since vitamin E is a fat-soluble vitamin, it has some of the properties of fat.
The recommended dietary allowance (RDA) for vitamin E is 10 mg/day for the adult man, 8 mg/day for the adult woman, and 3 mg/day for the infant. Vitamin Eoccurs in foods in a variety of related forms. The most potent and useful form of vitamin E is called alpha-tocopherol. The best sources of vitamin E arevegetable oils, such as corn oil, soy oil, and peanut oil. Animal fats, suchas butter and lard, contain lower levels of the vitamin. Corn oil contains about 16 mg of alpha-tocopherol per 100 g oil. Wheat-germ oil contains 120 mgalpha-tocopherol per 100 g oil. Fish, eggs, and beef contain relatively low levels of the vitamin, with about 1 mg per 100 g food.
Vitamin E seems to have only one function in the body: the prevention of thenatural and continual process of deterioration of all body tissues. This deterioration is provoked by a number of causes; one of these is toxic oxygen. During the body's metabolism of atmospheric oxygen, toxic oxygen is produced continuously in the body by the formation of by-products. These toxic by-products include hydrogen peroxide, superoxide, and hypochlorite.
Hypochlorite is a natural product, produced by cells of the immune system. Itis also the active component of bleach. Once formed, toxic oxygen can damagevarious parts of the body, such as the membranes which form the boundaries of every cell. Vitamin E serves the body in protecting membranes from toxic oxygen damage. In contrast, vitamin C serves to protect the aqueous, or watery,regions of the cell from toxic oxygen damage. The membranes that are most sensitive to toxic oxygen damage are the membranes of nerves; therefore, the main symptom of vitamin E deficiency is damage to the nervous system.
As mentioned, when vitamin E deficiency occurs, it strikes people with diseases that prevent the absorption of dietary fats and fat-soluble nutrients. These diseases include cystic fibrosis, cholestasis (bile-flow obstruction). Bile salts, produced in the liver, are required for the absorption of fats. Cholestasis causes a decrease in the formation of bile salts and the consequent failure of the body to absorb dietary fats. For this reason, this disease mayresult in vitamin E deficiency. Premature infants may be at risk for vitaminE deficiency because they may be born with low tissue levels of the vitamin,and because they have a poorly developed capacity for absorbing dietary fats.Infants suffering from fat-malabsorption diseases can develop symptoms of vitamin E deficiency by age two. In adults, the onset of a fat-malabsorption disease can provoke vitamin E deficiency after a longer period, as an example,ten years.
Vitamin E deficiency in humans results in ataxia (poor muscle coordination with shaky movements), decreased sensation to vibration, lack of reflexes, andparalysis of eye muscles. One particularly severe symptom of vitamin E deficiency is the inability to walk.
Vitamin E status is measured by assessment of the content of alpha-tocopherolin the blood plasma, using a method called high-pressure liquid chromatography. Blood plasma levels of alpha-tocopherol that are 5.0 mg/l, or above, indicate normal vitamin E status; levels below 5.0 mg/l indicate vitamin E deficiency.
Vitamin E deficiency that occurs with cholestatic liver disease, or other malabsorption syndromes, can be treated with weekly injections of 100 mg alpha-tocopherol that may continue for six months. Vitamin E deficiency in prematureinfants may require treatment for only a few weeks.
The prognosis for correcting the neurological symptoms of vitamin E deficiency is fair to excellent.
The prevention of vitamin E deficiency should not be a concern for most people, since the vitamin is found in a wide variety of foods. Attention has beengiven to the theory that vitamin E serves to protect against cancer and atherosclerosis. The evidence that normal levels of vitamin E protect against atherosclerosis is fairly convincing. However, there is little or no proof that vitamin E intake, above and beyond the recommended daily allowance (RDA), canprevent cancer or atherosclerosis.