What are peptides?

Peptides are short chains of amino acids that play a role in regulating hormones, releasing neurotransmitters, and repairing tissue, according to Adam Taylor, director of the Clinical Anatomy Learning Centre at Lancaster University.

Over 100 drugs approved by FDA are peptide-based, including insulin and some GLP-1 medications like Ozempic.

"'Peptides' is a broad umbrella that includes everything from well-studied, FDA-approved therapies to experimental compounds marketed for anti-aging with limited human data," said Brad Younggren, a physician and CEO and co-founder of Circulate Health in Seattle.

Synthetic peptides have gained popularity among wellness influencers and biohackers, who often take them via injection, hoping to enhance their athletic performance and optimize their health. Different peptides have different claims associated with them, but some of the most popular purport to enhance muscle growth, improve immune function, and slow aging.

Avinish Reddy, a longevity-focused concierge physician in Los Angeles, said he's seen an increased interest in peptides among his patients.

"It's become very common for patients to tell me they have friends taking a certain peptide and that they 'swear by it,'" he said.

What the science says about the benefits of peptides

FDA warns that synthetic peptides not approved by the agency pose "serious safety risks," including allergic reactions. FDA has banned their production by compounding pharmacies in the United States, however personal use is legal.

Most of the research on peptides has been done in labs on animals, not humans, according to Paul Knoepfler, a cell and molecular biologist at the University of California, Davis. Depending on the peptide, the science can theoretically make sense, he said, but he warned that using an untested peptide could cause serious harm.

For example, some studies in animals suggest that the peptide BPC-157 can help with tissue repair as it accelerates the growth of new blood vessels. But Knoepfler warned that this peptide could also theoretically encourage the growth of precancerous cells.

Younggren said that the science on peptides is "promising in specific areas" but added that peptides as a whole are "not a single, proven longevity solution."

"Peptides may be useful tools in select clinical contexts, but claims of universal rejuvenation are ahead of the evidence," Younggren said.

Knoepfler also noted the same substance that's helpful at one dose could be ineffective or harmful at another dose.

"You can't just make up what dose to take," Knoepfler said. But without more research, the therapeutic dose is unknown. "There's often no apparent rhyme or reason to the wellness peptide doses people are taking," he said.

Knoepfler added that if anyone is set on taking peptides, they should first consult with their physician.

Howard Sklamberg, a former FDA deputy commissioner, agreed that people should talk with their doctors before taking peptides. "At least if you're talking to your doctor, you're talking to somebody who can, theoretically, be held accountable."

Amanda Kahn, who runs a concierge practice in Midtown Manhattan, said many of her patients come to her seeking second or third opinions for issues like inflammation or chronic pain. In some instances, the popularity of peptides has outpaced the science, Kahn said, but she will prescribe them as an "adjunct" therapy if she thinks it's appropriate.

However, Kahn said she ensures her patients understand the drugs are experimental. "I don't overpromise that this is a cure-all," she said.

Perez emphasized the importance of being conservative if someone is starting peptides. "Understand the science, know the source, and get medical guidance," he said. "Peptide therapy isn't one-size-fits-all; it's nuanced and still evolving."