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Dietary supplements: Using vitamin and mineral supplements wisely
From MayoClinic.com
Special to CNN.com

Can you skip your daily servings of fruits and vegetables and take a vitamin and mineral supplement instead? Unfortunately, no.

Dietary supplements aren't meant to be food substitutes, as they can't replicate all of the nutrients and benefits of whole foods, such as fruits and vegetables. But dietary supplements can still play a role in your health by complementing your regular diet if you have trouble getting enough nutrients.

Vitamin and mineral ABCs

Vitamins and minerals are substances your body needs in small but steady amounts for normal growth, function and health. Together, vitamins and minerals are called micronutrients. Your body can't make most micronutrients, so you must get them from the foods you eat or, in some cases, from dietary supplements.

  • Vitamins. These nutrients are needed for a variety of biological processes, among them growth, digestion and nerve function. Vitamins are involved in many processes that enable your body to use carbohydrates, fats and proteins for energy and repair. Though vitamins are involved in converting food into energy, they supply no calories.
  • Minerals. These nutrients are the main components in your teeth and bones, and they serve as building blocks for other cells and enzymes. Minerals also help regulate the balance of fluids in your body and control the movement of nerve impulses. Some minerals also help deliver oxygen to cells and help carry away carbon dioxide.

Whole foods: Your best source of micronutrients

Whole foods are your best sources of vitamins and minerals. They offer three main benefits over dietary supplements:

  • Greater nutrition. Whole foods are complex, containing a variety of the micronutrients your body needs — not just one. An orange, for example, provides vitamin C but also some beta carotene, calcium and other nutrients. A vitamin C supplement lacks these other micronutrients.
  • Essential fiber. Whole foods provide dietary fiber. Fiber can help prevent certain diseases, such as diabetes and heart disease, and it can also help manage constipation.
  • Protective substances. Whole foods contain other substances recognized as important for good health. Fruits and vegetables, for example, contain naturally occurring food substances called phytochemicals, which may help protect you against cancer, heart disease, diabetes and high blood pressure. Many are also good sources of antioxidants — substances that slow down oxidation, a natural process that leads to cell and tissue damage. If you depend on dietary supplements rather than eating a variety of whole foods, you miss the benefits of these substances.

Who needs dietary supplements?

Many people don't receive all of the nutrients they need from their diet because they either can't or don't eat enough, or they can't or don't eat a variety of healthy foods. For some people, including those on restrictive diets, dietary supplements can provide vitamins and minerals that their diets often don't. Pregnant women and older adults have altered nutrient needs and may also benefit from a dietary supplement.

Choosing and using supplements

If you decide to take a vitamin or mineral supplement, consider these factors:

  • Check the supplement label. Read labels carefully. Product labels can tell you what the active ingredient or ingredients are, which nutrients are included, the serving size — for example, capsule, packet or teaspoonful — and the amount of nutrients in each serving.
  • Avoid supplements that provide 'megadoses.' In general, choose a multivitamin-mineral supplement — for example, Centrum, One-A-Day, others — that provides about 100 percent of the Daily Value (DV) of all the vitamins and minerals, rather than one which has, for example, 500 percent of the DV for one vitamin and only 20 percent of the DV for another. The exception to this is calcium. You may notice that calcium-containing supplements don't provide 100 percent of the DV. If they did, the tablets would be too large to swallow.
  • Look for 'USP' on the label. This ensures that the supplement meets the standards for strength, purity, disintegration and dissolution established by the testing organization U.S. Pharmacopeia (USP).
  • Beware of gimmicks. Synthetic vitamins are usually the same as so-called "natural" vitamins, but "natural" vitamins usually cost more. And don't give in to the temptation of added herbs, enzymes or amino acids — they add mostly cost. Note that some herbs can interact negatively with certain medications.
  • Look for expiration dates. Dietary supplements can lose potency over time, especially in hot and humid climates. If a supplement doesn't have an expiration date, don't buy it. If your supplements have expired, discard them.
  • Store all vitamin and mineral supplements safely. Store dietary supplements in a dry, cool place. Avoid hot, humid storage locations, such as the bathroom. Also, store supplements out of sight and away from children. Put supplements in a locked cabinet or other secure location. Don't leave them on the counter or rely on child-resistant packaging.

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  • June 05, 2006

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