Audio long read: Is the peptide craze backed by science? The promise behind the hype

**Benjamin Thompson** (0:02)
This is an audio long read from Nature. In this episode is the peptide craze backed by science, the promise behind the hype, written by Cassandra Williard and read by me, Benjamin Thompson.
Peptides have become the latest cure-all trend on social media. A way to eliminate wrinkles, build lean muscle, boost metabolism, clear brain fog, heal torn ligaments and more. Influencers rave about their peptide-fueled glow-ups on TikTok. Bodybuilders exchange information about their favorite combinations at the gym. US. Health Secretary Robert F. Kennedy Jr. is a proponent. I'm a big fan of peptides, he told US podcaster Joe Rogan in February. I've used them myself and used them with really good effect on a couple of injuries.
Peptides are made of the same building blocks as proteins, but are shorter. Typically less than 50 amino acids long. And they can be powerful medicines. The hugely successful GLP-1 diabetes and weight loss drugs, for example, are peptides, as is the hormone insulin. But when wellness gurus and fitness enthusiasts talk about peptides, they're often referring to an alphabet soup of chemicals. BPC-157, MOTC and TB500.
These compounds come in vials labelled for research use only, because they are not approved for use in humans. It's a quote, completely unregulated industry, end quote, says Vikas Patel, an emergency medicine physician at Elmhurst Hospital in Illinois. The popularity of peptides has skyrocketed over the past couple of years. Google searches on the term worldwide rose from about 1.3 million each month in 2024 to around 8 million per month in 2026 The enthusiasm has been driven, in part, by social media. The influencer crowd has sort of created this perception that these are miracle drugs, says Matt Cableyne, a longevity researcher at the University of Washington in Seattle. And although the obsession is a global phenomenon, people in the United States seem particularly enamored with them, says Patel. He attributes the phenomenon to a growing suspicion of the medical establishment in the country. We've hit this tipping point of people not trusting physicians or science, says Patel, who has also co-founded a private longevity clinic. Patel doesn't sell or prescribe peptides, but says that he does point people to the most reliable vendors if they decide to seek them out. But what does the science say? Animal research suggests that many of these experimental peptides hold promise for treating certain conditions. The evidence that these compounds work in people, however, is lacking.
That hasn't stopped Kennedy from pushing to make them more accessible. In April, the US Food and Drug Administration, the FDA, which he oversees, began the process of removing regulatory hurdles that prevent many of these compounds from being made in specialized pharmacies. Former FDA official Peter Lurie, now executive director of the Center for Science in the Public Interest, a non-profit organization in Washington DC that advocates for evidence-based food and health policies, worries that authorizing pharmacies to make and sell unproven therapies will deter companies from investing in drug development. It reduces the incentive, if not abolishes it entirely, for people to bring potentially effective drugs to market through the drug approval process, he says. And then what we'll have are a bunch of peptides on the market being sold and nobody generating any evidence to separate out the effective from the ineffective. Peptides occur naturally in the human body and perform essential functions. They serve as growth factors, neurotransmitters, anti-microbials and more. Tens of thousands have been identified and many more probably exist. Although made of the same amino acid building blocks, peptides are much shorter than proteins. Some arise when larger proteins are cleaved. Insulin, for example, comes from a larger protein called pro-insulin that is split in the pancreas. Others are encoded by the human genome, but not by the 20,000 to 25,000 canonical protein coding genes that have been identified. Rather, they are part of the dark proteome, hidden in vast swathes of DNA and once dismissed as irrelevant, says Pincas Cohen, a geroscience researcher at the University of Southern California's School of Gerontology in Los Angeles. These hidden peptides, quote, expand the scope of the human genome to possibly a million genes, end quote. Peptides are attractive as therapeutics because they tend to be smaller than proteins and bind more specifically to their target than do small molecules. They generally have less off-target interactions, says Carrie Haskell-Wevano, a peptide chemist at the University of Minnesota in Minneapolis. But peptides also come with some drawbacks. They aren't as stable as proteins and they often degrade quickly in the body. These are challenges that can be overcome, Haskell-Wevano says. In fact, they already have. Nearly 100 FDA-approved drugs are peptides, including oxytocin, human growth hormone and the GLP-1 drugs. Around 150 more are in clinical trials. Peptides can be very powerful substances, says Paul Knopfler, a stem cell biologist at the University of California, Davis, who has been following the debate over peptides closely. And he says, quote, There is no reason to think there aren't going to be dozens of other peptide drugs that are going to be proven safe and effective, end quote. Cohen began to get excited about peptides a couple of decades ago. He and his team had started mining mitochondrial DNA for peptide-encoding genes and synthesizing the molecules to study their function. One of their finds was MOTS-C.