Saturday, 4 June 2016

Dietary supplements often promise more than they deliver

pills isolated on white background
by Julie Corliss

Years ago, troubled by intermittent bouts of intense nausea that befuddled my doctor, I turned to a naturopath for help. In addition to suggesting some changes in diet, she recommended an herbal supplement called slippery elm bark. I dutifully took it for several weeks. My nausea faded away and hasn’t returned. I’ll never know what did the trick—the slippery elm bark, the diet changes, or the tincture of time.

As someone who’s dabbled with herbal and other dietary supplements, I’m in good company. About half of Americans say they take least one dietary supplement. That term covers vitamins, minerals, herbs, and related products. As a nation, we spend more than $32 billion each year on some 85,000 different supplements. Some people, like me, use them to treat a specific ailment. But many others just want to improve or maintain their health.

Unfortunately, some people fall prey to unscrupulous supplement peddlers. Take the octogenarian profiled in an article published online this week in JAMA Internal Medicine. Three clinicians from the University of California, San Francisco describe how the man, worried about memory loss, was spending nearly $3,000 a month on more than 50 supplements recommended by his “anti-aging” physician, plus hundreds of dollars more on other products he chose himself. Most of the products had no proven benefit on memory, and some may have contributed to the memory loss he was so worried about.

“This is an extreme example of a person who was essentially ripped off by someone he trusted to care for him,” says Dr. Pieter Cohen, a dietary supplement safety researcher and assistant professor of medicine at Harvard Medical School. But there are many other examples of people who either waste their money or are harmed—sometimes fatally—by dietary supplements.

People often assume that dietary supplements are harmless because they are “natural.” Lax marketing standards make the problem worse. Supplement makers can claim their products enhance health, despite a dearth of evidence in most cases. Unlike pharmaceuticals, which undergo extensive testing to prove they’re effective and safe before they can be sold, dietary supplements can be sold with without proof of effectiveness, safety, or purity.

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. (You can hear an interview with Dr. Cohen about the safety of nutritional supplements here.) The offenders include stimulants, bodybuilding 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 other prescription medications.

For example, a man prescribed nitrates to treat his chest pain should not take an erectile dysfunction drug such as Viagra. Doing so can cause dangerously low blood pressure. “So he takes an ‘all-natural’ herbal supplement instead. But he’s actually getting the Viagra his doctor told him not to take,” says Dr. Cohen, noting that many products contain compounds similar to or identical to Viagra, sometimes in doses higher than prescribed versions of the drug.

Many experts agree that the laws to regulate supplements need to be reformed. But Congress has shown no appetite for that, and any changes will probably be years in the making. In the meantime, if you’re interested in taking a dietary supplement, what steps can you take to minimize the risk? Dr. Cohen offers these tips:
  • Consider only single-ingredient supplements. In a multi-ingredient supplement, knowing which substance is having an effect—either good or bad—is impossible to tease out. Also, these products are more likely to be adulterated with banned drugs. So stick to single-ingredient supplements.
  • Do your research. At MedlinePlus, a health information website for consumers from the National Institutes of Health, you can find information about the effectiveness, usual dosage, and drug interactions of dietary supplements (see Some of the listings feature data from the independent Natural Medicines Comprehensive Database, which provides unbiased, up-to-date facts and ratings on the safety and effectiveness of more than 1,100 natural medicines.
  • Talk to your doctor. Few health care providers have the time to stay current on the staggering number of supplements on the market. But they can check if a particular ingredient interacts with any of the medicines you’re currently taking.
  • Look for the USP or NSF stamp. The United States Pharmacopeia (USP) and NSF International are independent, nongovernmental organizations that test dietary supplements. USP verifies the identity, quality, strength, and purity of supplements; NSF confirms that the supplement contains the listed ingredients and nothing else. Look for one of these stamps on the label, but keep in mind that neither indicates anything about the effectiveness of the product.

No comments:

Post a comment