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Cornell University : Cornell Cooperative Extension
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| Yates Association |
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Are Vitamin Supplements Necessary? |
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Most people don't need to take vitamin supplements, but nearly 40% of American adults do anyway. Are supplements really necessary for good health, and what are vitamins? The body produces many of the chemicals it needs to maintain proper function. There are many compounds, however, that the body can't make including some amino acids and a few fatty acids. Vitamins are required in very small amounts. These compounds which the body can't make are provided by foods in the diet. Most foods generally contain at least one or more different vitamin. However, no food contains all the vitamins in the correct amounts required by the body. It is important to eat a wide variety of foods to insure an adequate intake of all the necessary nutrients. How much of the vitamins does a person need? The National Research Council establishes daily allowances for these necessary nutrients on the basis of recommendations made by scientists chosen for their research experience on vitamins in human metabolic studies. The allowances are set at a generous level to cover most healthy people's requirement with a reasonable margin of safety. Comparing these allowances against the nutrient composition of a typical varied diet demonstrates that adequate amounts of nutrients are provided by average amounts of food. A diet of fruits and vegetables, dairy products, enriched or whole grain products along with some meat or meat substitute should provide all the nutrients that a healthy person needs without having to take supplements. What about megadoses? Research has been done to explore any advantages to taking vitamins in excess of the recommended levels. To date, there is no evidence to support vitamin supplementation for improving athletic performance, cold or flu resistance, memory, or treating certain diseases, yet some people continue taking megadoses of 5-20 times the recommended allowance! Not only hasn't a benefit been shown for taking an excess, but there have been clear indications of toxic reactions to excessive vitamin intakes. Toxicity is a hazard when large amounts of certain vitamins, particularly fat soluble vitamins like A and D, are taken. Excess amounts of these are stored in the body tissues rather than being excreted. Amounts too small to cause toxicity, but still well in excess of the recommended allowance, may interfere with normal body processes such as nerve impulse transmission, body protein formation, hormone action, or blood circulation. Large doses of one vitamin can block the body's ability to use another vitamin. Excesses of water soluble vitamins like B and C are for the most part excreted, but megadoses of these vitamins can still cause problems. Large doses of C may be a problem for patients with gout and/or a tendency to form kidney stones. Diabetics taking more than 500 mg of vitamin C daily may obtain false readings in their urinary glucose test. The RDA is 60 mg. Are there any conditions where vitamin supplements are necessary? Supplemental vitamins may be suggested by a doctor for people who have very irregular eating habits. People who are eating a diet low in calories to lose weight may need supplements since the reduced food quantity may not contain adequate amounts of some nutrients. Pregnancy is another example of a condition where supplementation may be advised by a physician. In fact, most doctors recommend folic acid supplements for all women of childbearing age. Megadoses of vitamins may be useful in treating certain rare vitamin dependent genetic disorders and in certain malabsorption syndromes. Self-prescribed, large doses of vitamins, however, can pose serious health risks. People with special health problems should check with their doctor about the need for vitamin tablets. Cornell
Cooperative Extension Yates Association |
