Supplementing Your Diet: Vitamins, Minerals and Beyond

Dr. Coates explains that, for the most part, supplement "megadoses" haven't been tested. "Absence of evidence of harm isn't the same as evidence of absence of harm," he says. "In many cases we just don't know."

It's not difficult to get high doses of certain nutrients, either. Breakfast cereals have long been fortified with vitamins and minerals. Now, many other fortified products are crowding onto grocery shelves as consumers buy into the idea that more is better. Look at the foods and supplements you're eating together to make sure that your total intake of any one nutrient isn't too high. If you're concerned, talk to a health care provider such as a doctor, pharmacist or registered dietitian or check the nutrient recommendation information at the ODS web site.

Dietary supplements beyond traditional vitamins and minerals have also become popular. In one study, about 19%, or 1 out of every 5 people surveyed, used natural products such as echinacea, ginseng, glucosamine and ginkgo biloba. But since they're regulated more like foods than drugs, in a lot of cases we don't know how or even if these supplements work as their supporters claim.

"Be prepared to ask questions," Dr. Coates advises. "These products are available on drug store shelves, supermarket shelves and vitamin store shelves in packaging that makes them look like drugs, but they aren't regulated like drugs. Consumers have to realize that the drug rules don't apply."

Haggans adds, "People assume if it's on the shelf it must be safe and we must know a lot about it, but that's not necessarily the case."

The National Center for Complementary and Alternative Medicine (NCCAM) takes the lead at NIH in funding studies of supplements beyond traditional vitamins and minerals. They now have dozens of studies under way to test their safety and effectiveness.

In the meantime, if you're considering taking a supplement, consult with your health care provider. Some supplements can interfere with other medications, so have a list ready of all the medications and supplements you're taking or considering.

If you decide that a particular dietary supplement is right for you, make sure you're buying a reliable brand. There are independent laboratories that test supplement products for quality and purity. "There are companies whose products are made to very high standards," Dr. Coates says, "but that's not always the case."

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