Vitamins Health Article

Definition

Vitamins are organic components in food that are needed for growth and for maintaining good health. They include the fat-soluble vitamins, such as vitamin D, vitamin E, vitamin A, and vitamin K; and the water-soluble vitamins, such as folate (folic acid), vitamin B₁₂, biotin, vitamin B₆, niacin, thiamin, riboflavin, pantothenic acid, and vitamin C (ascorbic acid). Vitamins are required in the diet in only tiny amounts, in contrast to the energy components (sugars, starches, fats, and oils).

Purpose

People are treated with vitamins for three reasons. The primary reason is to relieve a vitamin deficiency when one has been detected. Chemical tests suitable for the detection of all vitamin deficiencies are available. The diagnosis of vitamin deficiency is often aided by visual tests, such as the examination of blood cells with a microscope, the x-ray examination of bones, or a visual examination of the eyes or skin.

A second reason for vitamin treatment is to prevent the development of an expected deficiency. In this case, vitamins are administered even with no test for possible deficiency. One example is vitamin K treatment of newborn infants to prevent bleeding. Food supplementation is another form of vitamin treatment. The vitamin D added to foods serves the purpose of preventing the deficiency from occurring in people who may not be exposed much to sunlight and who fail to consume foods that are fortified with vitamin D, such as milk. Niacin supplementation prevents pellagra among people who rely on corn as the main source of food and who do not eat much meat or milk. In general, the U.S. food supply is fortified with niacin.

A third reason for vitamin treatment is to reduce the risk for diseases that may occur even when vitamin deficiency cannot be detected by chemical tests. One example is folate deficiency. The risk for cardiovascular disease can be slightly reduced for a large fraction of the population by folic-acid supplements. These supplements can also sharply reduce the risk for certain birth defects.

Vitamin treatment is important during specific diseases where the body's normal processing of a vitamin is impaired. In these cases, high doses of the needed vitamin can force the body to process or utilize it in the normal manner. One example is pernicious anemia, a disease that tends to occur in middle age or old age; it impairs the absorption of vitamin B₁₂. Surveys have revealed that about 0.1% of the general population, and 2% to 3% of the elderly, may have the disease. If left untreated, pernicious anemia leads to nervous-system damage. The disease can easily be treated with large daily oral doses of vitamin B₁₂ (hydroxocobalamin) or with monthly injections of the vitamin.

Vitamin supplements are widely available as over-the-counter products. But whether they work to prevent or curtail certain illnesses, particularly in people with a balanced diet, is a matter of debate and ongoing research. For example, vitamin C is not proven to prevent the common cold, yet millions of people take it for that reason.

Precautions

Vitamin A and vitamin D can be toxic in high doses; side effects range from dizziness to kidney failure. High doses of niacin can be toxic to the liver, while excessive intake may occur with vitamin C, especially among the elder. Doses of vitamin K can have toxic effects in infants. A physician or pharmacist should be consulted about the correct use of a multivitamin supplement that contains these vitamins.

Description

Vitamin treatment is usually done in three ways: by replacing a poor diet with one that supplies the recommended dietary allowance (RDA), by consuming oral supplements, or by injections. Injections are useful for persons with diseases that prevent absorption of fat-soluble vitamins. Oral vitamin supplements are especially useful for people who otherwise cannot or will not consume food that is a good vitamin source, such as meat and dairy products. For example, a vegetarian who will not consume meat may be encouraged to consume oral supplements of vitamin B₁₂.

Treatment of genetic diseases that impair the absorption or utilization of specific vitamins may require megadoses of the vitamin throughout one's lifetime. Megadose means a level of about 10 to 1,000 times greater than the RDA for a particular vitamin. Pernicious anemia, homo-cystinuria, and biotinidase deficiency are three examples of genetic diseases that are treated with megadoses of vitamins.

Preparation

The diagnosis of a vitamin deficiency usually involves a blood test. An overnight fast is usually recommended as preparation prior to the blood test so that vitamin-fortified foods do not affect the test results.

Aftercare

The response to vitamin treatment can be monitored by chemical tests, by an examination of red or white blood cells, or by physiological tests, depending on the exact vitamin deficiency.