Millions of Americans believe nutritional supplements provide health benefits. They’re convinced the “natural” ingredients in these non-prescription products (pills, powders, liquids, and gummies) can prevent diseases, make them feel better, and slow down the effects of aging.

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Supplement sales in the U.S. topped $51 billion dollars in 2022, according to a market analysis by Grand View Research. “Consumers are increasingly made aware of such products and their benefits through effective marketing campaigns, influencer endorsements, and social commerce,” the report noted.

All that marketing is working. More than half of adults in the U.S. (55 percent) take nutritional supplements regularly, according to a recent survey by the Council for Responsible Nutrition, an industry trade group. Most of the respondents (74 percent), including those who do not use these products, said they “trust” the dietary supplement industry.

But is that trust warranted? Consumer advocates caution that, in many cases, it’s not. They’re concerned about the way these products are often marketed, and the lack of government oversight to ensure quality, safety, and effectiveness.

“Strong evidence to back up claims made for dietary supplements is often lacking,” according to the National Center for Complementary and Integrative Health (NCCIH), part of the National Institutes of Health.

NCCIH points to a review done in 2022 of 27 ingredients frequently included in supplements with claims related to immune function, such as “supports healthy immune system” or “natural immune booster.” The conclusion:

“The reviewers searched the scientific literature for rigorous studies in people on the effectiveness of each ingredient, and they found evidence of this type for only eight of them. 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

A new prescription drug cannot be approved for sale until the manufacturer proves it is safe and effective. There is no such regulatory standard for supplements.

The Food and Drug Administration (FDA) does not review or approve supplements prior to sale. In most cases, manufacturers are not even required to notify the FDA when they introduce new products.

“They’re completely unregulated, so people really don’t know what they’re getting when they buy things over the counter,” 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 on supplements means that the product is safe; that doesn’t have anything to do with safety or efficacy.”

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 notice or simply disregard it.

But are you even getting what’s promised? With no requirements for premarket quality testing, 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 the drug sibutramine, an appetite suppressant now banned in the U.S.

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

Congress mandated this hands-off approach when it passed the Dietary Supplement Health and Education Act (DSHEA) in 1994, 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 when supplements are found to be contaminated or are making 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.

Misleading Marketing

Congress gave supplement makers a lot of 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.” And a manufacturer couldn’t claim its product “prevents colds and flu,” but can promise 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 “So, 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 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 told Checkbook. “There are a lot of outrageous and misleading claims being made without any proof of efficacy about what these supplements can do.”

Consumers are really motivated by the magic words “clinically tested” or “clinically proven.” They’re more likely to believe the marketing for products that make these claims, “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 claim.

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 Leanfire 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 disease and other forms of dementia become more common, the demand for supplements that promise to boost brain health, improve mental sharpness, and improve memory has grown.

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

Unfortunately, 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 for Supplements

Some supplements can be beneficial when recommended by your doctor and certified for quality. I take Vitamin D because blood tests showed my levels were low. Many people take multivitamins every day. That doesn’t guarantee good health, but for must of us these types of supplements won’t do any harm.

But with so little oversight of the supplement market, you need to 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 one of three quality assurance seals: ConsumerLab, USP (U.S. Pharmacopeia), and NSF (NSF International). You can trust them more because their testing is done by independent organizations that check that products contain the ingredients on their labels, are free of contaminants, and disintegrate fast enough to enter the bloodstream. However, these products haven’t been tested to determine whether they deliver promised health benefits.

Keep Your Doctor in the Loop

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 National Institutes of Health says about two popular supplements:

• St. John’s wort can weaken the effect of many “crucially important medications, 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, make sure your medical provider knows. 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 your condition.

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