Glowing skin, deeper sleep, stronger muscles, an alert mind?
Such are the enticing promises of peptides, an increasingly buzzy class of substances touted by influencers and celebrities as the key to an optimized life.
Starting Thursday, a US review panel convened by the Food and Drug Administration is to consider whether seven of these peptides should be recommended for compounding -- when pharmacists or outsourcing facilities create custom drugs -- as interest in them surges.
Many medical experts have warned against that recommendation, citing a lack of evidence.
"There's just not enough clinical data to say whether these peptides are safe and effective," said Alexander Weber, an orthopedic surgeon and chief of sports medicine at the University of Southern California.
And yet, "peptides come up with my conversations with patients every single day," he told AFP.
The substances under review -- including BPC-157, TB-500 and Semax -- are among those Joe Biden's administration restricted from compounding, notably over lack of human clinical trial data.
But that hasn't thwarted use in many cases. Substances can be purchased online from chemical suppliers "for lab use only."
Wellness influencers, industry advocates, and Robert F. Kennedy Jr -- President Donald Trump's health chief, who says he has used peptides to treat injuries -- say the restrictions have fueled gray markets of overseas suppliers with no oversight or standards.
"With the gray market you have no idea if you're getting a good product," Kennedy said in an interview this year with podcast host Joe Rogan. "And a lot of this stuff that we've looked at is just very, very substandard."
Medical experts accuse Kennedy of packing the FDA advisory panel with people who have strong ties to the peptide industry, given his personal interest in the products.
"In ordinary circumstances, I would say that these products are dead," Peter Lurie, president of the Center for Science in the Public Interest and a former FDA official, told AFP.
"But given the way that the committee is stacked," he said, "I don't have that confidence at all."
- 'Alarming safety concern' -
Peptides are short chains of amino acids, which are the building blocks of proteins.
They are naturally occurring in the body, signaling molecules that dictate major physiological processes like tissue repair or metabolism.
Insulin is a peptide, for example.
GLP-1 medications like Ozempic are also peptides: they mimic a naturally occurring molecule that regulates appetite, blood sugar and digestion.
Both of those treatments are well-studied.
But the synthetic peptides touted by influencers and biohackers, which are often injectable, are not.
Such substances have not undergone the kind of large-scale trials the FDA would normally require to establish safety and efficacy.
The FDA's own career scientists have published documents outlining concerns that even if peptides are trendy, evidence to support loosening restrictions is still inadequate.
Their conclusions mirror those of a white paper jointly published in May by the nonprofit ECRI and the Institute for Safe Medication Practices (ISMP).
"The commercial market has grown faster than the clinical evidence base," the paper read, and "the absence of adequate clinical evidence for use in humans is an alarming safety concern."
Rita Jew, the ISMP president, told AFP "there's no new information that will make us feel comfortable" that the seven peptides should be authorized for compounding.
- Genie out of the bottle? -
Ed Lee is an Orlando-based endocrinologist who is hopeful for compounding approvals, especially for BPC-157, which is popular in the wellness community for its purported ability to repair tissues, including muscles and ligaments.
Lee co-founded the "Clinical Peptides Society" and started a petition called "Save Peptides" which has garnered nearly 10,000 signatures and urges federal legislators to loosen restrictions on peptides.
"I don't know how they're going to put the genie back in the bottle," Lee told AFP.
But for Lurie, the argument that demand should inevitably lead to a stamp of approval falls short given the "extremely thin science."
"If at the end of the day these products are approved, I see nothing good coming out of it," he said.
Weber said his patients have relayed positive anecdotes regarding peptide use -- but cautioned such anecdotes are not enough to guide use more broadly, without deeper research.
"There's a lot of bias that goes into that two cents," Weber said.
"If you're paying for something, you want it to work."
