Visit a health food store, and you'll likely find products that claim to quickly and easily improve your health. And Americans are buying into this idea of a convenient fix, spending $6 billion a year on nutritional supplements.* One quarter to one-third of Americans take daily vitamin supplements, and 70 percent take nutritional supplements at least occasionally.*

  Focusing on nutrition is a wise step towards protecting your health. But which vitamins do you need, and how much of them? Should you be taking supplements? Does it matter whether you ingest vitamins via supplements or food?

  Vitamins and essential minerals (which together are called "micronutrients") are substances required in tiny amounts to promote chemical reactions in your cells. Vitamins are needed for growth, digestion, mental alertness and resistance to infection. While vitamins act as catalysts for various body processes, you don't get energy (calories) from them.

  Following is a chart of the 11 most important vitamins. The chart shows how each vitamin affects your body, which foods are natural sources and how high doses may affect you.

  Your body works to maintain an appropriate amount of each vitamin and must keep the amount circulating in your bloodstream constant. Surplus water-soluble vitamins (vitamin C and the eight B vitamins: thiamin, riboflavin, niacin, vitamin B6, pantothenic acid, vitamin B12, biotin and folic acid) are excreted in your urine, rather than being stored. Surplus fat-soluble vitamins (A, D, E and K) are stored in body tissue. Because they are stored, excess fat-soluble vitamins can accumulate in your body and become toxic. 

  While vitamins E and K appear to be safe in large amounts, it is recommended that you do not take vitamin E supplements before surgery or vitamin K supplements if you're taking anticoagulents. The body is especially sensitive to excess amounts of vitamins A and D, so most experts recommend avoiding high doses. In addition, high doses of B3 (niacin) can cause flushing and itching, and very high doses of B6 (pyridoxine) over long periods can lead to neurological problems.

  The American Dietetic Association, the National Research Council and other major medical societies all agree that you should get the vitamins and minerals you need by eating a well-balanced diet.* While some high-risk individuals may benefit from a nutritional supplement, healthy adults can get all their necessary nutrients from food. Experts prefer food to supplements for supplying vitamins, because food contains hundreds of additional nutrients. If you rely solely on supplements, you may be missing out.

  However, the Mayo Foundation for Medical Education and Research recognizes that many people don't eat properly. Skipping meals, dieting and eating meals high in sugar and fat are common practices that leave adults short of vitamins. While adopting better eating habits would be the desirable way to ingest more nutrients, taking supplements may be a reasonable option. But vitamin-mineral supplement dose levels should be no higher than 100 percent of the Recommended Daily Allowance. Doses above the RDA don't give extra protection, but do increase your risk of serious side effects.

  If your want to improve your nutritional health, working to eat a well-balanced diet should be your first step. For more information on proper nutrition and multi-vitamin supplements, contact your physician.

*Information Source: Medical Essay, Mayo Foundation for Medical Education and Research, June 1999;  New Choices, April 1998.