Start vetting your supplements

There are plenty of good reasons to take a dietary supplement. Maybe you're deficient in a particular vitamin or mineral, such as vitamin D or iron, or you have a poor diet and your doctor recommends a multivitamin. Or perhaps there aren't many ways to treat a health problem you have, such as osteoarthritis, and your doctor says it won't hurt to try a certain supplement that has a small chance of easing symptoms.

So there you are, standing in the supplement aisle of a drugstore, savvy enough to be wary of dietary supplements yet wondering how to recognize the bad ones. Fortunately, certain strategies and online tools can help.

Be cautious about quality

The supplement industry is notorious for producing products that don't contain what they claim. "The FDA leaves it up to companies to ensure the purity and safety of their products. But there's not much incentive. It rarely penalizes manufacturers for not having the right amount of ingredients in a product," says Dr. Pieter Cohen, an associate professor of medicine at Harvard Medical School who studies supplements.

For example, recent research by Dr. Cohen and his colleagues found that 25 brands of gummies with melatonin (used to promote sleep) contained dangerously high levels — up to 347% more melatonin than what was listed on labels. Some of the brands they tested also contained the marijuana derivative cannabidiol (better known as CBD), also at levels that exceeded label claims.

What you can do: Look for supplements with certification seals from vetted independent third parties. "Most seals of approval are meaningless. But the U.S. Department of Defense [DOD] has identified several certifying organizations that do a good job ensuring supplements are labeled accurately," Dr. Cohen says.

DOD-approved certifying organizations include the U.S. Pharmacopeia (www.quality-­supplements.org) and NSF International's Certified for Sport program (/nsf/cps). Both test many types of supplements.

Beware of hidden ingredients

The FDA is seeing an increase in supplements that contain hidden prescription drugs, controlled substances, or untested and unstudied components. If you use these products, there's a risk that they might cause serious side effects or interact with medications you're taking. The tainted supplements are widely available and sold online from sellers on eBay or Amazon and even through large retail stores.

What you can do: Look up ingredients you don't recognize on FDA websites that can help you identify potentially dangerous products or supplement ingredients.

One useful reference is the Dietary Supplement Ingredient Directory (/dsid), unveiled in March 2023. It enables you to quickly look up dozens of different ingredients and get basic information as well as links to research and warnings about them.

The other is the Health Fraud Database (/hfpd), which lists some (but not all) products that have been subject to FDA-related violations.

Go over a checklist

The DOD has a resource anyone can use to check if a supplement seems safe. It's called the Operation Supplement Safety Scorecard (/opss/dietary). The scorecard provides a checklist of seven questions you can answer quickly to determine if a supplement seems safe. For example:

• Is there an approved third-party certification seal on the product label? (The scorecard displays images of the seals to look for.)
• Is the label free of claims or statements that seem questionable to you?
• Are there fewer than six ingredients on the label?

If you don't get at least four "yes" answers to the questions on the scorecard, the supplement is designated too risky to take.

Do some digging

Do a little detective work if your clinician suggests that you take a supplement, especially a botanical treatment (made of plants or plant extracts).

"Be skeptical," Dr. Cohen suggests. "Ask if there's a study about it. But it needs to be a large randomized controlled trial to be credible."

You can also look up medical studies on your own by going to a reliable search engine called PubMed (www.pubmed.ncbi.nlm.nih.gov) from the National Institutes of Health (NIH).

NIH also provides fact sheets on a wide variety of dietary supplements. Check them out (/dsfs) and see if there's a good reason to take the supplement you're considering. If not, it's probably safer to skip the risk.

Image: © AsiaVision/Getty Images