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Nutrition and Weight Control Special Report

Dietary Supplements: Yea or Nay?

While vitamin B12, calcium, and vitamin D are really the only dietary supplements you may need to stay healthy as you get older, many people are still tempted to try other supplements. In this Special Report Johns Hopkins helps you see beyond the hype and understand the risks and benefits of the dietary supplements you take.

Stop! Before you take a dietary supplement, it's important to consider whether you really need it. Sure, supplements sound like a good idea, but the U.S. Food and Drug Administration (FDA) doesn't regulate them for safety and effectiveness -- meaning their marketing doesn't have to be supported by good scientific data -- and manufacturers often make outlandish claims about their benefits.

Supplements may contain all sorts of substances -- from herbs and botanicals to amino acids, enzymes, and animal extracts -- that don't have enough evidence to support their supposed health-promoting properties. Some "natural" supplements have proven effective because potent drugs are added; others contain dangerous amounts of contaminants, such as heavy metals.

You should always discuss any supplements you're taking with your doctor or nutritionist since they may interact with your medications to cause a serious reaction. For instance, vitamin K can decrease the effectiveness of the blood thinner warfarin (Coumadin) and increase clotting. Calcium can also negatively interact with the heart medicine digoxin (Digitek, Lanoxin) as well as certain antibiotics and drugs. Supplements can also worsen a medical condition, pose a danger before or after you have surgery, or put you at risk for overdosing on certain vitamins and minerals. (For example, many supplements exceed safe levels of vitamin A.)

Beneficial Supplements for Seniors Experts advise that you meet your nutritional needs first and foremost by consuming a variety of healthy foods as set forth in the Dietary Guidelines for Americans (for information, visit That said, certain vitamin and mineral supplements can help older people get the right amounts of nutrients -- but they are intended to supplement the diet, not to replace the foods you should be eating.

The following dietary supplements are recommended for seniors:

  • Vitamin B12. Since many older adults don't absorb this vitamin efficiently from foods, guidelines advise either a supplement at a dose of 2.4 micrograms (mcg) a day or a combination of fortified foods and supplements that adds up to this amount. Foods with naturally occurring vitamin B12 don't count toward this goal. The Dietary Guidelines for Americans say that people over age 50 should be encouraged to consume vitamin B12–fortified products, such as breakfast cereals, or to take the crystalline form of vitamin B12 in supplements.
  • Vitamin D. With aging, the body has a more difficult time absorbing vitamin D from foods or making it when exposed to sunlight. Yet adequate vitamin D is important in helping to prevent the bone loss that can occur with aging. The Dietary Guidelines recommend that older adults get 1,000 IU a day from vitamin D-fortified foods such as breakfast cereals, orange juice, and milk, plus fatty fishes like salmon, tuna, and mackerel -- and from dietary supplements if needed. Most supplements contain 400 IU of vitamin D, so taking one or two a day in addition to eating fortified foods should suffice.
  • Calcium and vitamin D for postmenopausal women. An authoritative panel convened by the U.S. government reviewed data from well-designed trials of supplements and concluded that calcium and vitamin D increase bone density and decrease the risk of hip and other fractures in older men and women.

Experts recommend 1,200 mg of calcium a day for older adults and 1,000 IU of vitamin D. Calcium from dietary supplements is best absorbed in doses of 500 mg or less, so if you are taking more than that in supplements, take it in divided doses.

What To Ask Before Taking a Supplement
Review the following questions, recommended by the FDA, and share your answers with your doctor or nutritionist so together you can decide whether you should take a vitamin or mineral supplement:

  • Do you eat fewer than two meals a day?
  • Do you eat a restricted diet? For instance, do you not eat meat, milk, or milk products, or fewer than five servings of fruits and vegetables a day?
  • Have you lost or gained more than 10 lbs in the past six months without trying to?
  • Do you take three or more prescription or over-the-counter medications a day?
  • Do you drink three or more alcoholic beverages a day?

Also consider:

  • What are the intended benefits of the product?
  • How, when, and for how long will you need to take it?

Posted in Nutrition and Weight Control on December 3, 2008


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