Pinchas Cohen, the USC Leonard Davis School of Gerontology dean whose lab identified MOTS-c as a metabolic signaling peptide years ago, says he learned only a few months ago that tens of thousands of people are injecting themselves with black-market versions of his discovery. The peptide, which mimics certain effects of exercise when administered to mice, carries no FDA approval and no completed human safety trials, yet it circulates widely online in vials stamped "for research use only." News-Tribune reporting published August 18, 2026, captures Cohen describing the trade as "illegal, from unknown sources, unknown purity, unknown sterility."
Cohen told the outlet he "strongly objects" to the current distribution model, in which longevity influencers and fitness communities promote MOTS-c as "exercise in a bottle" despite the absence of human efficacy or dosing data. His alarm arrives the same week an FDA advisory panel voted to recommend that compounding pharmacies be permitted to manufacture six unapproved peptides, including MOTS-c, BPC-157, TB-500, KPV, epitalon, and Semax. Live Science reported that scientists cautioned the panel's recommendation does not constitute proof of safety or effectiveness.
The tension Cohen now faces is personal and regulatory. Roughly 250 papers from dozens of laboratories worldwide have examined MOTS-c since his team first characterized it, and the peptide's effects on mouse metabolism, including improved endurance and blood-sugar regulation, have appeared compelling in preclinical work. No one has established how long-term use affects humans, what dosage would be therapeutic, or whether the compound interacts dangerously with other substances. Influencers' claims about human weight loss, muscle gain, and longevity remain extrapolations from animal data.
Figure 1: Biomedical laboratory assay and analytical documentation.
Cohen traveled to Washington, D.C., to testify before the FDA Pharmacy Compounding Advisory Committee, many of whose members work for telehealth, longevity, and wellness companies with a financial stake in the peptides' regulated availability. His position surprised some observers: given that MOTS-c is already in wide off-label use and no published research has documented harmful side effects, Cohen argued that "quality-controlled, prescriber-supervised" compounding represents the safest available path. "We can't stop the black market," he said, according to the News-Tribune account. "So I think it's a better choice to at least guarantee the quality, the sterility, and require that real doctors are part of the process."
FDA staff scientists who spoke at the two-day committee meeting disagreed. They advised against peptide compounding, stating there was not enough safety data to justify the move. Paul Knoepfler, a stem-cell and regenerative-medicine researcher at UC Davis, told the panel that even purer compounded versions would not address the "potential inherent risks of the peptides themselves" and saw "no special reason they should be allowed to bypass the standard clinical trial system just because there's a peptide fad driven by wellness influencers and telehealth firms." The Live Science report noted that "allowed to be compounded" does not mean "FDA-approved," a distinction Stanford peptide researcher Katrin Svensson emphasized.
The "for research use only" label on retail vials functions as the legal hinge that keeps the online trade operational. Sellers avoid making therapeutic claims, which would classify the product as an unapproved drug subject to FDA enforcement. Buyers, however, overwhelmingly purchase the vials for self-injection. For readers tracking how these compounds move through gray-market channels, our explainer on research peptides outlines the labeling conventions and regulatory gaps that enable the trade.
Cohen acknowledged that his ideal outcome, developing MOTS-c into a fully FDA-approved drug, would require at least a decade and hundreds of millions of dollars in clinical development, a path very few peptide candidates complete. His own efforts to advance MOTS-c through that pipeline remain ongoing but incomplete. In the interim, the compound continues to circulate in a space where neither the seller nor the buyer can verify sterility, concentration, or absence of contaminants.
Whether the FDA will act on the advisory panel's compounding recommendation, and on what timeline, has not been announced. The panel's vote is non-binding. Until the agency issues a formal rule or Cohen's team publishes human safety data, the question of whether MOTS-c buyers are getting a pure compound or a contaminated one rests entirely with the anonymous supplier at the other end of an online order. Those weighing the personal risk can review our reporting on whether research peptides are safe in the absence of clinical oversight.
