"A lot of people want to add something natural and alternative to the conventional medications they're taking, and they assume that dietary supplements might help and can't hurt," says Dr. Pieter Cohen, a dietary supplement safety researcher and assistant professor of medicine at Harvard Medical School. But that's not the case.
Unlike pharmaceuticals, which undergo extensive testing to prove they're effective and safe before they can be sold, dietary supplements can be sold without proof of effectiveness or safety. Moreover, supplement makers can claim their products improve health, even when there's little or no evidence to support such claims.
Multivitamins are one of the most popular supplements taken by people trying to prevent heart disease. But large, "gold standard" trials have shown that taking a daily multivitamin does not ward off heart disease. Small studies suggest that some dietary supplements, such as red yeast rice, lowers cholesterol, a risk factor for heart disease. Yet the amount of the active ingredient in red yeast rice products varies widely, from very low to very high. And up to one-third of red rice yeasts products may be contaminated with a kidney toxin called citrinin.
Such contamination isn't rare. As Dr. Cohen noted in a perspective in The New England Journal of Medicine, the FDA has found more than 500 supplements adulterated with pharmaceuticals or closely related compounds. The offenders include stimulants, body-building steroids, antidepressants, weight-loss medications, and supplements aimed at treating erectile dysfunction. All can cause unwanted side effects and may be especially risky when taken with heart drugs or other prescription medications.
Because of the potential risks and unclear benefits of dietary supplements, most doctors advise their patients to avoid them, though they may recommend specific supplements such as calcium and vitamin D to prevent osteoporosis.
For most people, "a well-balanced diet rich in whole foods including fruits, vegetables, fish, olive oil, and nuts negates the need for any supplements," says Dr. Cohen.
Read the full-length article: "Dietary supplements: Sorting out the science"
Also in the August 2014 issue of the Harvard Heart Letter:
- The role of triglycerides in heart disease
- Artery-opening angioplasty through the wrist
- How to prevent a second stroke
The Harvard Heart Letter is available from Harvard Health Publications, the publishing division of Harvard Medical School, for $20 per year. Subscribe at www.health.harvard.edu/heart or by calling 877-649-9457 (toll-free).
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