I must have seen commercials for Prevagen 50 times: story after story from everyday people who describe improvement in memory once they began taking Prevagen. And perhaps you recall older commercials playing off the idea that many people take supplements that boast of gut, joint, and heart health claims. Those commercials memorably asked, “So why wouldn’t you take something for the most important part of you… your brain? With an ingredient originally found in jellyfish! Healthier brain, better life!”

Never mind that the ingredient from jellyfish (apoaequorin) that was supposed to deliver these benefits has no known role in human memory. Or that many experts believe supplements like this are most likely digested in the stomach and never wind up anywhere near the brain.

Can a supplement actually improve memory? If it doesn’t work, why is the manufacturer allowed to suggest it does? And if apoaequorin is so great, why aren’t jellyfish smarter (as a colleague of mine wonders)?

Mind the gap between graphics and reality

A bar graph in the older ads showed a rise from 5% to 10% to 20% over 90 days in “recall tasks,” though exactly what that meant was never explained. Nor were we told how many people were studied or given any information about effects on memory after 90 days.

One small, company-sponsored study reported improvements in memory after people took apoaequorin. However, the published version demonstrated improvements only in a subset of study participants. And the real-world impact of these changes is uncertain. The study authors recommended additional research to clarify its effectiveness. But I’ve been unable to find any additional, high-quality, independent studies showing the impact of Prevagen or apoaequorin on human memory.

The Prevagen case resolved

The US Federal Trade Commission (FTC) and the New York state attorney general were also unconvinced about the supplement’s benefits. Back in 2017, they charged the supplement maker with false advertising. Fast forward to February 2024, when a New York jury found that many of the supplement’s claims were not supported by reliable evidence, and some (but not all) of the claims were “materially misleading.”

In December 2024, the FTC and New York attorney general won their lawsuit. Now the makers of Prevagen are prohibited from claiming that the supplement can improve brain function or memory.

Supplement claims sound good — so why the disclaimers?

There are many thousands of supplements marketed for hundreds of conditions. But it’s often hard to say if they’re doing much of anything.

For example:

• Glucosamine is often promoted as good for joint health. I have known patients who swore by it. But the best studies suggest this supplement has modest effects, if any.
• When vitamins tout heart-healthy claims, I think of the example of vitamin E, once considered potentially useful to prevent or treat heart disease. Yet, study after study showed no benefit. In fact, it may increase the risk of heart failure.
• As for probiotic supplements, no convincing evidence shows that their use improves digestive health or prevents digestive disease in healthy people.

So when you’re considering supplements, be skeptical of the benefits touted and remember the standard disclaimer stamped on each one: “These statements have not been evaluated by the FDA.”

What are the rules?

Supplement makers are bound by a few basic rules set by the FTC and FDA:

• They can make truthful claims about connections between their supplement and the body’s “structure and function.” For example, a vitamin maker touting calcium in a product can say that calcium is important for bone health — although it’s also true that calcium supplements may offer little or nothing for most people with healthy bones, diets rich in calcium, and no medical condition requiring extra calcium.
• They cannot claim their product treats or prevents a particular disease. That disclaimer, which may seem to contradict marketing promises, must appear on every package. So, commercials suggesting that a supplement can reverse or slow Alzheimer’s disease, or any dementia, may run afoul of the rules on marketing supplements.

The FDA and FTC continue to provide key oversight to the dietary supplement industry. That’s a daunting task given the sheer volume of products on the market.

The bottom line

This country has an enormous appetite for dietary supplements. The supplement industry is now worth an estimated $70 billion or more, with as many as 100,000 products available for purchase.

But there’s a reason dietary supplements carry a disclaimer: “This product is not intended to diagnose, treat, cure, or prevent any disease.” This should remind us all to be wary of claims we see in ads for dietary supplements. Unlike prescription drugs, supplements are not thoroughly tested or evaluated. While dietary supplements might provide benefits in certain cases, it’s vitally important that their makers not make unfounded claims to exploit consumers.

I support the efforts of the FDA and FTC to regulate dietary supplements and their ads. But regardless of how effective their regulations are, it’s best to be skeptical about ads for products that seem too good to be true. There’s a good chance they are.

About the Author

Robert H. Shmerling, MD, Senior Faculty Editor, Harvard Health Publishing; Editorial Advisory Board Member, Harvard Health Publishing

Dr. Robert H. Shmerling is the former clinical chief of the division of rheumatology at Beth Israel Deaconess Medical Center (BIDMC), and is a current member of the corresponding faculty in medicine at Harvard Medical School. … See Full Bio View all posts by Robert H. Shmerling, MD