St. John’s wort capsules to boost your mood. Horny goat weed gummies to “promote libido.” Swedish Fish-flavored energy powder to…help gamers focus better? Scads of nutritional supplements sold in the U.S. tout “natural” ingredients and abilities to prevent diseases, make people feel better, and slow down the effects of aging.

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American consumers are snapping up these products and gulping them down: In 2022, U.S. consumers spent $51 billion on supplements, according to a market analysis by Grand View Research. More than half of American adults take nutritional supplements regularly, per a recent survey by the Council for Responsible Nutrition, an industry trade group, and most of that study’s respondents (74 percent) said they “trust” the dietary supplement industry.

But that trust might not be warranted. Consumer advocates caution that supplements are often deceptively marketed, and that a lack of government oversight means it’s difficult to ensure their quality, safety, and effectiveness.

“They’re completely unregulated, so people really don’t know what they’re getting,” said Dr. John Swartzberg, head of the editorial board at the UC Berkeley Wellness Letter. “[People] believe that if the label says this supplement has a certain amount of a certain chemical, that they can trust that. You can’t necessarily. They believe that the word ‘natural’ means that the product is safe; that doesn’t have anything to do with safety or efficacy.”

Plus, many ingredients that supplement sellers say will make you feel better simply won’t. The National Center for Complementary and Integrative Health (NCCIH)—part of the National Institutes of Health (NIH)—cites a 2022 review of 27 ingredients frequently found in supplements that claim to boost immune systems. After searching scientific literature and studies, the researchers found supporting evidence of efficacy for only eight of the 27 ingredients. The NCCIH noted that some of the studies “suggested possible benefit, but the evidence wasn’t strong enough to allow definite conclusions to be reached.”

Most Supplements Are Sold with No Oversight

In the U.S., new prescription drugs cannot be approved for sale until manufacturers prove they are safe and effective. But the Food and Drug Administration (FDA) does not review or approve supplements, and, for the most part, manufacturers are not even required to notify the FDA when they introduce new products.

Congress mandated this hands-off approach in 1994 when it passed the Dietary Supplement Health and Education Act (DSHEA), following intense lobbying from the supplement industry. As a result, the Wellness Letter explains, dietary supplements are “regulated as a class of foods, not drugs,” and therefore, “it is the responsibility of the FDA to prove that supplements are harmful.”

Because of DSHEA, the FDA’s main role is to investigate after supplements are found to be contaminated or to have made people sick. And that does happen: Each year, an estimated 23,000 emergency department visits in the U.S. “are attributed to adverse events related to dietary supplements,” resulting in an estimated 2,154 hospitalizations, according to a 2015 study published in The New England Journal of Medicine.

Supplement packages and advertisements are required to include a disclaimer stating the FDA has not evaluated their products or the claims they make, but most consumers miss the fine print.

Are you getting what’s promised? With no premarket quality testing requirements, supplement manufacturers can claim their products provide a wealth of benefits with no proof. Even if a product is beneficial, a manufacturer could still replace an expensive ingredient with a cheaper alternative, or add a banned drug without disclosing it.

The nonprofit Center for Science in the Public Interest (CSPI) cautions that weight loss and sports performance supplements have been found to contain “dangerous, prohibited amphetamine-like stimulants.” Some sexual enhancement supplements include “Viagra-like drugs,” and some weight-loss supplements have tested positive for sibutramine, an appetite suppressant banned in the U.S.

“It is illegal to add any drug—banned or not, dangerous or not—to supplements,” CSPI’s Nutrition Action magazine noted.

Misleading Marketing

Congress gave supplement makers ample marketing leeway when it passed DSHEA 30 years ago, but there are some limits. Companies can’t claim their products prevent, treat, or cure a disease. But they can boast that the product “supports” or “maintains” some structure or function of the body.

For example, a supplement can’t claim to “reduce depression,” but it can promise to “help improve your mood.” Similarly, a manufacturer can’t tout that its product “prevents colds and flu,” but can advertise it will “support the immune system.”

“Companies are also really good at just keeping things vague, but tapping into our psychology with allures to vitality, energy, or just being your best self,” said Caitlin Dow, CSPI’s senior nutrition scientist. “They’re not really saying anything, but it’s inspiring, and that’s all they need to say to stay out of the FDA’s line of sight and to attract consumers.”

These “linguistic loopholes” sell a lot of products, Dow told Consumers’ Checkbook. Most people can’t tell the difference between something that says it “supports joint health” versus “will relieve knee pain,” she said. “They read those [statements] the same way.”

But some supplement makers cross the line, cautioned Bonnie Patten, executive director and co-founder of Truth in Advertising, a nonprofit that exposes false advertising and deceptive marketing.

“[They] find it economically advantageous to lie to consumers about what these products can and cannot do,” Patten said. “There are a lot of outrageous and misleading claims being made without any proof of efficacy.”

Consumers are motivated by the magic words “clinically tested” or “clinically proven.” They’re more likely to believe the marketing, “even though it may be that the company doesn’t really have the appropriate scientific backing to make those claims,” Patten said.

Just because something was tested doesn’t mean it was good science. In many cases, the companies selling the product paid for the research.

“It’s almost comical how bad the research on some of these is,” Dow said. “It’s not about health; it’s about marketing.”

Some companies fund studies that don’t include a placebo testing group, which makes any conclusions meaningless, or they test for something that really doesn’t matter. Another trick: Pay to have the study published in a low-tier journal to add credibility to the nebulous claims.

Supplement companies often use fine print to protect themselves from accusations of false advertising. A few years ago, a commercial for LeanFire supplements from Force Factor claimed they could “double your weight loss.” But CSPI caught the fine print qualifier that appears on screen for only a few seconds, which said: “Results not typical. Healthy diet and exercise recommended for optimal results.”

Forget Memory Pills

As the country ages and cases of Alzheimer’s and other forms of dementia become more common, there’s a growing demand for supplements that promise to boost brain health, mental sharpness, and memory.

About one in five (21 percent) of Americans age 50 and older take a vitamin or dietary supplement for brain health, according to a 2021 survey by AARP.

Health experts caution that the marketing claims for these expensive supplements do not match the science.

“Most of the research on these supplements for brain health has come up empty despite these promising claims, despite the promising testimonials,” CSPI’s Dow said. “There has been some research showing that some memory supplements contain unapproved drugs, too, which is illegal. So, I’d say pass.”

Shop Smart

If blood tests show you have low levels of certain nutrients (Vitamin D or folic acid), your doctor may recommend a supplement. And many people take multivitamins every day. These habits don’t guarantee good health, but for most of us, they won’t do any harm.

But be careful what you buy, and where. Most quality claims, such as “third-party lab tested” or “made with good manufacturing practices,” sound impressive but are meaningless—and not verified by the FDA.

Health experts recommend looking for products certified by at least one of three independent organizations: ConsumerLab, USP (U.S. Pharmacopeia), and NSF (NSF International). These organizations check that products contain the ingredients on their labels, are free of contaminants, and disintegrate fast enough to enter the bloodstream.

But know that even products that bear these quality seals were not tested to determine whether they actually deliver promised health benefits.

Loop in Your Doctor

Your physicians need to know if you take supplements because they can interfere with both prescription and non-prescription medications, making them more potent (and possibly toxic) or less potent (and therefore ineffective).

For example, here’s what the NIH says about two popular supplements:

• St. John’s wort can weaken the effect of many “crucially important medicines,” including antidepressants, birth control pills, warfarin (blood thinner), some statins (including simvastatin), some heart medications (including digoxin), and some HIV drugs.
• Ginkgo biloba can interact with some conventional medications, including anticoagulants (blood thinners). It may be “unsafe” to take orally during pregnancy.

Some supplements, such as chaparral, comfrey, kava, and skullcap, can cause liver damage, especially when taken long-term or in high doses, the FDA cautions.

Bottom line: If you’re going to take supplements, tell your medical provider. If you have a medical problem, rather than self-medicating with supplements, talk to your doctor. There may be treatments or even dietary measures that could help.

More Information:

UC Berkeley Wellness Letter:
A Guide to Dietary Supplements

CSPI Nutrition Action newsletter:
Why the Supplement Aisle Is the Wild West
How Supplements Distort Science to Sell
Tricks of the Trade: Are Supplement Companies Playing You for a Fool?

Truth in Advertising (TINA.org):
Jury Hands Down a Verdict in Prevagen Deceptive Marketing Case
Consumer Alert: Hair Growth Products