Taking Dietary Supplements Safely

Excerpts from an educational webinar from NIH's Office of Dietary Supplements, featuring Dr. Paul Thomas and Ms. Carol Haggans.

Dietary supplement use in the United States:

Thomas: Americans spend more on supplements than they do on over-the-counter medications, like products for pain relief, stomach upset, allergies, and the like. One good estimate is almost $49 billion in sales in 2019.

Overall, about half of adults and a third of children take one of more supplements daily, or on most days. For adults, supplement use increases with age. About a third of those [aged] 19 to 30 take them. [This grows] to three-quarters of older people in their 70s and beyond.

People take supplements for many different reasons, but I think we can put them into three major categories. First, some [use] supplements as a form of nutritional insurance, to be sure they get the recommended amounts of nutrients. Another reason is the hope or expectation of better health over the short or long term. Although dietary supplements, by definition, aren’t meant to treat diseases. And then some people take supplements for specific purposes. [For example], a bodybuilder or runner might supplement to see if that improves their strength or performance.

How the Food and Drug Administration (FDA) regulates dietary supplements:

Haggans: If you think about prescription or over-the-counter drugs, we expect them to work as intended and to be safe. FDA doesn’t treat dietary supplements the same. Dietary supplements are regulated as foods and not drugs.

First, they’re [not approved] for effectiveness. So that means that if you take a supplement that’s marketed to help maintain immune systemThe system that protects your body from invading viruses, bacteria, and other microscopic threats. health, or suppress your appetite, it may or may not work.

And likewise, FDA doesn’t approve supplements for safety. And there are no mandatory standards for ingredient combinations or doses. And furthermore, for the FDA to ban a supplement, the burden of proof is on them to prove that it’s unsafe. And sometimes that can be a high bar.

So it’s important to do your homework when considering [if] you should take a supplement. Especially ones that contain ingredients that are less well studied than others, like herbs.

Even though manufacturers don’t have to prove to FDA that their supplements are effective, they’re allowed to make certain claims about them. For example, manufacturers can claim that their product “helps maintain normal cholesterol levels” or “supports the immune system.” But they can’t say that a product “lowers cholesterol” or “has antiviral capabilities.” But you can see that there’s a fine line between what’s allowed and what isn’t. And in reality, many people might interpret those claims [as being the same].

How botanical and herbal supplements are different from vitamins and minerals:

Thomas: There are no guideposts or recommendations for intake [for botanicals], like you have with the daily value for nutrients. So you need to get expert advice on when or if to take [a botanical] product.

For most botanicals, we don’t know what the most important constituents are, or what combinations provide potential health benefits. And one company’s botanical supplement is [going to be] different from another’s. Each contains different amounts and combinations of the [compounds] that might affect your health.

The safety of a botanical depends on many things, like how it’s prepared and the amount you use. For example, peppermint tea is generally considered safe to drink. But peppermint oil taken as a supplement is much more concentrated and can be toxic if used incorrectly.

And be really careful about taking botanical supplements if you also take prescription medications. In some cases, there’s a possibility of an unwanted interaction between the two. For example, St. John’s wort, which some people use for mood disorders, can reduce the effectiveness of many medications, like some birth control pills, anti-depressants, and [organ] transplant drugs.

Questions to ask before taking a supplement:

Thomas: The best advice we can give you is to talk with your health care providers before taking any supplements. Have a discussion with your doctor, pharmacist, registered dietitian, or other provider about which might be useful—or useless—to you. At the very least, let your main providers know what supplements you’re taking and why. Discuss your reasons for taking them and get their reactions.

[Questions to ask can include]: What are the potential benefits for me? Does it have any safety concerns or safety risks? What is the proper dose to take? How, when, and for how long should I take it?

Be especially skeptical of taking a supplement other than a standard vitamin, mineral, or prenatal supplement if you’re pregnant or [breastfeeding]. We often don’t know if an ingredient might affect a developing or nursing baby. Also be skeptical about giving these types of supplements to an infant or child. Many supplements haven’t been well tested for safety in pregnant women, nursing mothers, and kids.