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JAMA Forum Archive, 2012-2019: Health policy commentary from leaders in the field
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Given Their Potential for Harm, It’s Time to Focus on the Safety of Supplements

Supplements, including vitamins, minerals, and herbal products, are a huge business in the United States. US consumers spend about $30 billion on them every year. Despite uncertain benefits and possible harm, their interest in supplement use, for children as well as adults, remains undeterred.

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A recent study published in JAMA Pediatrics used National Health and Nutrition Examination Survey data to examine supplement use among children. The researchers used 6 recent waves of the survey (from 2003-2004 through 2013-2014), specifically focusing on children and adolescents through 19 years of age. Parents provided answers to questions if the children were younger than 16 years.

Respondents were asked if they had “used or taken any vitamins, minerals, herbals, or other dietary supplements in the past 30 days.” If they answered “yes” to any questions, they were asked—in person—to show containers for those supplements so that the answers could be confirmed and recorded.

Supplements were grouped into 2 categories. Those that consisted mostly of vitamins or minerals were called “nutritional products.” Others, like herbal supplements, and those not consisting mostly of vitamins and minerals were called “alternative medicines.” About a third of children and adolescents—a massive number—use dietary supplements. Multivitamins were the most common nutritional product, followed by omega-3 fatty acids.

Increasing Use of Alternative Medicines

Nutritional product use has remained steady over time, but the use of alternative medicines increased from 3.7% to 6.7%. Much of this increase was due to more children and adolescents using omega-3 fatty acids and melatonin.

It’s important to stop at this point and ask why. Fish oil supplements and the fatty acids they contain have been studied pretty extensively in adult populations who might actually be at risk of heart disease, and that research has found that they didn’t seem to work. There’s absolutely no evidence that they are useful in children. Other alternative products, like melatonin, are being used more often, even though data on children—certainly safety data—are lacking. In other cases, alternative medicines such as nootropics, drugs that are supposed to advance cognitive function, are gaining in popularity, too.

Even the nutritional product use is of questionable benefit for many individuals. Do we really believe that the vast majority of children in the United States are deficient in vitamins and minerals? I’m not talking about children with diagnosed deficiencies, which are rare, and then absolutely need to be treated.  Most cases of deficiencies involve vitamin D deficiency in kids younger than 1 year or iron deficiency in children aged 1 to 5 years. The vast majority of children who take a multivitamin are healthy children who—if anything—are likely getting more than enough.

Drug-Drug Interactions and Other Concerns

Concerns about supplement use are not limited to children. A study published in JAMA Internal Medicine in 2016 looked at how the prevalence of dietary supplements and over-the-counter medication use changed among the elderly from 2005 to 2011. More than 2000 people, on average older than 70 years, were interviewed twice. Between 2005 and 2011, over-the-counter medications decreased from 44% to 38%. The use of supplements, however, increased from 52% to 64%.

Researchers were especially concerned about how these products might potentially be the cause of major drug-drug interactions, a concern also raised by the JAMA Pediatrics study. Although clinicians spend a large amount of time checking for potential problems in the pharmaceuticals they  prescribe, relatively little is spent on potential problems from supplements. The electronic health record often doesn’t ask or know about them—let alone flag them for problems, and neither do pharmacists.

That’s a real problem. The study of elderly adults found that the potential for major drug-drug interactions from supplements increased significantly from 2005 to 2011, increasing from 8% to more than 15%.

It’s bad enough that so many US consumers are taking supplements, which can be expensive, often provide no proven benefit, and may not even have what the bottle labels say they contain. What’s worse is that many of these supplements may also be increasing the potential for adverse outcomes because of other medications that they’re already taking. About 23 000 visits to emergency departments each year can be attributed to adverse events from dietary supplements.

Supplement producers do not need to prove that their products work before selling them to people. There’s little regulation, so these products can often wind up containing very little of what patients think they do. Many of them contain ingredients that have been banned for use in people or have never been studied. In 2016, when a researcher pointed this out, he was sued by a supplement maker.

Given that spending on supplements now approaches 10% of our overall spending on pharmaceuticals, it may be time to question their regulation or lack thereof. Even if we’re not going to require them to be held to the same standards as prescription drugs with respect to efficacy, it seems reasonable to at least increase our focus on them with respect to safety.

Anything we do for health has to be considered in the context of benefits and harms. When the former outweighs the latter, it’s reasonable to proceed. But in the case of supplements, for many if not most people, the benefits appear to be minimal to nonexistent. The potential harms on the other hand are real and documented. Given this, it’s hard to understand why patients are using them in such increasing numbers. Physicians may need to push back harder than we have in the past.

About the author: Aaron E. Carroll is a professor of pediatrics at Indiana University School of Medicine who blogs on health research and policy at The Incidental Economist, makes videos at Healthcare Triage, and tweets on Twitter at @aaronecarroll. (Image: Ted Grudzinski/AMA)