Toward safer supplements
By Tim Stoddard
Until recently, Cindy Christiansen considered dietary supplements marketed in health food stores, such as ginseng, kava, and ginkgo biloba, to be generally safe. Christiansen, an SPH associate professor of health services, reserved judgment on whether these products worked, but says she “would have said that dietary supplements are just like over-the-counter drugs. They wouldn’t be on the U.S. market if they weren’t safe, right? Of course, I was wrong in thinking that. They’re not regulated that way at all.”
Christiansen’s perspective on dietary supplements changed soon after she was invited by the National Academies’ Institute of Medicine and National Research Council to join a committee of experts advising the U.S. Food and Drug Administration (FDA) on how to better evaluate the safety of some 29,000 dietary supplements available to American consumers. Christiansen and her colleagues on the committee recently coauthored the report “Dietary Supplements: A Framework for Evaluating Safety,” which outlines several ways the FDA can identify supplement ingredients that may pose risks in humans, prioritize them based on levels of potential risk, and then evaluate them in a cost-effective and scientifically sound manner.
Dietary supplements include a diverse family of products such as vitamins, minerals, amino acids, hormones, and enzymes that purport to alleviate depression, expedite weight loss, and ward off the common cold. Since 1994, dietary supplements have been regulated as food instead of drugs, which means they are considered safe until proven otherwise, and are not required to be clinically tested before going on the market. It is up to the FDA to determine whether a particular substance on the market is harmful based on information available in the public domain, even when there’s scant evidence of a product’s safety for people.
For Christiansen, who is director of the statistics section at the Veterans Administration’s Center for Health Quality, Outcomes, and Economic Research in Bedford, Mass., serving on the committee was an unusual challenge. “Statisticians work with data,” she says, “and what’s so interesting about regulating dietary supplements is that there’s so little data on safety in people.” As the $18 billion dietary supplement industry continues to grow, with about 1,000 new products coming to market every year, the FDA has struggled to effectively monitor the safety of the supplements. “Part of my contribution to the committee,” she says, “was figuring out a way for the FDA to use existing data in the public domain to come up with safety recommendations, which means combining information across sciences.”
The committee report recommends the FDA be vigilant for “signals,” or warning signs, that a particular product or ingredient may be dangerous. These signals may arise when another country takes regulatory action against a dietary supplement or when an unusual pattern of illness or death emerges in the FDA’s Special Nutrition/Adverse Event Monitoring System. Data from animal studies and in vitro tests also can provide enough information on their own to warrant FDA action, the report says, even when there’s no direct evidence of harmful effects on people. According to the Dietary Supplement Health and Education Act, the FDA does not have to find direct harm in people to determine that a supplement has a risk; it just needs to show that a product poses an unreasonable risk to users.
Christiansen and her colleagues also recommend that the FDA watch out for substances that are chemically similar to products already known to be dangerous in humans. She points to ephedra, the herbal stimulant the FDA banned in April after a thorough investigation revealed that weight-loss products containing ephedra were implicated in heart attacks and strokes. “If you know that a suspect product such as ephedra is chemically related to something that you do know a lot about,” Christiansen says, “then you might think it will have some of the same side effects or safety issues as the better-known compound.”
Another potential problem with many dietary supplements is that the public assumes they are safe because they’ve been used for years. But the active ingredients in herbal remedies are often reformulated and packaged in a more concentrated form, Christiansen says, and the high-dose tablets marketed today can have very different effects from those with lower doses — herbal teas, for example. With that in mind, the committee suggests the FDA investigate reformulated ingredients even when their historical use is well documented.
As the FDA begins to digest the recommendations outlined in the report, Christiansen says, dietary supplements will remain on her radar screen in future research. She’s particularly interested in developing studies to form a clearer picture of how Americans incorporate dietary supplements into their overall health practices. Demand for dietary supplements continues to rise, as the public becomes more receptive to alternatives to conventional nutrition and medicine. “People want to have access to these things,” Christiansen says. “Some folks are fed up with the medical system and want to be able to self-medicate. Some people don’t have health insurance and can’t afford to go to doctors. They’ll buy dietary supplements because they can’t afford to do anything else. On a personal level, it really bothers me that a lot of vulnerable people are using these products. I would like to know that these supplements are safe for those people who can’t afford traditional care.”