Do vitamins and other supplements live up to their promise?

Dietary supplements are wildly popular. Over one millions Americans take at least one supplement. The attraction is understandable. Many people want to optimize their health and well-being. The supplement industry has a strong financial interest in meeting this need and promoting their products. But manufacturers do not need to prove the purity, strength, safety, or effectiveness of supplements. And the law does not require proof that claims on the label are true.

A recent issue of the Harvard Men's Health Watch gives readers an overview of the evidence (for or against) several popular supplements, including vitamin D, selenium, St. John's wort, and multivitamins. Harvey Simon, M.D., editor of the Harvard Men's Health Watch cautions readers, "Consumers should always keep an eye out for new study reports. Recommendations will change as scientific studies trickle in. Unfortunately, in most cases, the studies have failed to confirm our hopes, though there are exceptions."

Despite their popularity, there is no evidence that multivitamins enhance health or prevent illness. In fact, both the U.S. Preventive Services Task Force and a National Institutes of Health State-of-the-Science Conference concluded that multivitamins do not offer protection against heart disease or cancer. In contrast, research suggests that fish oil supplements may be beneficial for people with heart disease.

Dr. Simon recommends a thoughtful and careful approach. "It is often hard to balance sober scientific reports with the simple, hopeful promises of well-marketed vitamins and supplements." The Harvard Men's Heath Watch offers some tips for doing just that.

• Watch for extravagant claims. If it sounds too good to be true, it usually isn't true.
• Take testimonials and endorsements with a grain of salt, especially those from celebrities. Even the most sincere, well-intended recommen dations offered by friends and relatives without financial incentives can't establish a product's safety or efficacy.
• It isn't true that "if a little is good, more is better." In fact we have learned that even the most harmless sounding supplement can have unintended negative effects.
• Beware of meaningless terms. The list includes "all-natural," "antioxidant-rich," "clinically proven," "anti-aging," and other vague but seductive claims that a product can work wonders.

Even if you take supplements, be sure to eat well, exercise regularly, and work with your doctor to keep your cholesterol, blood pressure, and blood sugar in good control, advises the Men's Health Watch. Tell your clinicians about any and all supplements you take; full disclosure is important, particularly since supplements can have adverse interactions with medications.