Peptides are unproven as health aids. FDA may unleash them anyway

Pick an ailment — joint pain, brain fog, insomnia — and there’s probably a peptide therapy promising to treat it. Never mind that many of these amino acid–based products are not approved by the U.S. Food and Drug Administration, have hardly been studied in people and may not be intended for human use at all. Some people aren’t afraid to go DIY, buying peptides from online retailers or overseas suppliers and injecting them at home, whether their doctors know about it or not. 

There’s a clear solution for regulators dealing with an “illicit market” like the one emerging for peptides, says Mitch Zeller, a former FDA official who left the agency in 2022: “Step up your enforcement game” to stop its spread.

His successors at the FDA, however, appear to be taking a different approach. Rather than reining in the health-hacking peptide craze, they appear poised to take steps that will fuel it.

Health and Human Services Secretary Robert F. Kennedy Jr., a self-proclaimed “big fan” of peptides, seems to be following through on a vow to end what he called the FDA’s “aggressive suppression” of substances including peptides. In July, an FDA advisory committee is set to consider whether compounding pharmacies — which make drugs that aren’t commercially available or are in short supply — should be authorized to produce certain injectable peptides. Those under consideration include peptides that the FDA, under the Biden administration, directed compounding pharmacies to stop making due to safety concerns, including the possibility of immune reactions. 

And in March, the FDA held a public meeting to discuss the scope of ingredients allowed in oral dietary supplements, at which peptide proponents advocated for their inclusion. At that meeting, FDA Deputy Commissioner for Food Kyle Diamantas said the administration’s goals include “cutting out red tape,” signaling a potential openness to broadening what can be sold as a dietary supplement. Already, that category includes a wide range of ingredients — vitamins, minerals, herbs and more — that can be sold on promises to support general health and wellness, as long as they don’t claim to treat specific conditions. 

Supplements, unlike drugs, do not have to go through rigorous studies to prove safety and efficacy before hitting store shelves, meaning they are subject to minimal oversight, says Zeller, who worked on supplement issues at the FDA in the 1990s. Adding unproven peptides to these products, he says, would take the industry even further into “buyer-beware land.”

The FDA is still deliberating about peptides. An HHS spokesperson did not respond to questions, instead directing Science News to links about the upcoming meeting related to compounding pharmacies.

The agency’s actions, Zeller says, telegraph a “belief in the right to try” even unregulated substances that are not known to be safe and effective. The “only conceivable outcome,” he says, is that more people will feel emboldened to dose themselves with largely unstudied and unregulated peptides.

What are peptides, anyway?

Peptides are essentially “miniature proteins,” says John Fetse, a peptide therapeutics researcher at Binghamton University in New York. A complex arrangement of amino acids is a protein; a shorter chain of them is a peptide.

Peptides occur naturally in the body, as well as in many foods. They play a wide range of roles. The hormones insulin and oxytocin are peptides, for example, but peptides also show up in toxic animal venom. “All peptides are not the same,” Fetse says. “How you organize the building blocks really tells you what kind of effect you are going to have.” 

Synthetic — or lab-made — peptides can mimic those the body makes naturally, but with tweaks to make the compound “more druglike,” says Eileen Kennedy, president-elect of the nonprofit American Peptide Society. (The chemical biologist at the University of North Carolina’s Eshelman School of Pharmacy in Chapel Hill has no relation to Robert F. Kennedy.) They may be longer-lasting than natural versions, or raise concentrations beyond what would naturally occur in the body.

How have peptides been studied and regulated so far?

Some synthetic peptides are well-studied and FDA-approved. (The “P” in GLP-1, the wildly popular category of diabetes and weight-loss drugs that includes Ozempic, stands for “peptide.”) But many of the substances people are using to self-treat, with names like BPC-157 and TB-500, show promising effects in animal studies but have not been rigorously studied in humans, raising questions about whether they are safe and work as advertised. 

For example, BPC-157, a synthetic peptide derived from gastric juices found in the stomach, has been shown to accelerate healing from tendon injuries and wounds in rats, but human research has largely been limited to small case reports or pilot studies. A small human clinical trial was initiated in 2015 but canceled before results were reviewed and published. 

Currently, BPC-157 is on the World Anti-Doping Agency Prohibited List. The U.S. Anti-Doping Agency states that it “may lead to negative health effects.” Still, some people use it in hopes of boosting athletic performance, injury recovery and more.

“All peptides are not the same. How you organize the building blocks really tells you what kind of effect you are going to have.”

John Fetse
peptide therapeutics researcher

Consumers should “be patient” and “see what the clinical data says” before using peptides, Fetse says. 

Even peptides that closely mirror those made by the body itself can have different effects when administered like a drug, Eileen Kennedy says. A peptide naturally found in the stomach might set off a different reaction when injected into the knee to help heal a sports injury. Some people also take numerous different peptides in regimens known as “stacks,” and thus risk creating unexpected and potentially dangerous interactions, she says. 

Some doctors are willing to write prescriptions that allow people to buy certain peptides from compounding pharmacies — a process that still falls short of full safety and efficacy review, but that at least operates within the U.S. regulatory system. 

But “a lot of peptides aren’t going through that route,” Eileen Kennedy says. Instead, many people purchase them, unprescribed, from direct-to-consumer websites or overseas factories with minimal oversight. Sometimes, she says, these compounds are technically intended for research — not human consumption.

“In those cases, there isn’t really a guarantee of purity,” she says. “You might not even be getting the exact compound that you want.” 

What would it mean to include peptides in oral dietary supplements? 

Loose oversight also characterizes the current market for oral dietary supplements, another arena in which peptides are a topic of interest. Without a requirement for premarket safety and efficacy testing, the FDA typically intervenes only if a supplement causes health issues once it’s already for sale, Zeller says.

“It creates an environment where we have legalized snake oil,” says Pieter Cohen, an internal medicine physician at Cambridge Health Alliance in Massachusetts who studies supplement safety. “You can put anything in a bottle and start selling it.” 

That already includes peptides, to some extent. Oral collagen peptide supplements, for example, are already commonly marketed to support skin, bone, muscle and joint health. A 2025 meta-analysis supported some of these claims, finding that collagen peptide supplementation may improve bone mineral density and muscle function. 

Substances already found in the food supply are also generally considered fair game for inclusion in supplements. That includes certain peptides (collagen is found in meat and fish) as well as their building blocks, amino acids. The market is full of amino acid supplements that claim to help with athletic performance and plenty of other wellness goals. While a limited amount of research suggests athletes may benefit from their use, other studies have been less positive.

Many buzzy peptides, however, are not found in the food supply. BPC-157, for one, is “not a dietary ingredient. It is an unapproved drug and cannot be legally prescribed or sold over the counter,” according to Operation Supplement Safety, a Department of Defense educational project. 

Still, it’s easy to find dietary supplement capsules advertising it as an ingredient — and if the FDA decides to expand the scope of permitted supplement ingredients, it may get even easier. 

It’s noteworthy that “despite all those opportunities to include pretty much any chemical found in any food” regulators may allow even more substances to go into supplements without proactive safety and efficacy review, Cohen says. In addition to peptides, ingredients such as microbials were discussed at the March meeting.

If supplement makers begin adding peptides to their products, Zeller thinks they should be regulated like drugs, given the many outstanding questions about how peptides affect human health. “There should be premarket review, both of their safety and their potential benefit,” he says.

If that review took place, the results might be disappointing for manufacturers of oral supplements. When peptides are swallowed, enzymes in the stomach typically make quick work of digesting them. “If you swallow it in a supplement, you would probably see no therapeutic benefit at all,” Fetse says.