RFK Jr. is 'a big fan' of peptides. What are they?

A Food and Drug Administration (FDA) ban on a list of chemicals with "significant safety risks" could soon be lifted under the guidance of Health and Human Services Secretary Robert F. Kennedy Jr.

Kennedy said on a Feb. 27 episode of Joe Rogan's podcast that the FDA would announce "some kind of new action" around injectable peptides "within a couple of weeks," calling himself a "big fan of peptides."

"They’re still looking at the science, my hope is that they’re going to get moved to a place where people have access from ethical suppliers," he told the podcaster.

He pointed to 14 peptides that were banned by the FDA in 2023, saying he wanted to make them "more accessible" and accusing the Biden administration of putting them on a "do not produce" list "illegally." Kennedy said the agency had acted beyond its reach with the ban and created a black market to fill the void, an argument also made by the chemicals' manufacturers, some of whom later brought challenges in court.

The New York Times reported on March 31, citing a senior HHS official, that Kennedy's desires could soon come to fruition. HHS did not immediately respond to USA TODAY's request for comment.

Here's what to know about peptides and why some were previously banned.

What are peptides? What to peptides do?

Peptides are short strings of amino acids, the same organic compounds that serve as the building blocks for proteins. When a "chain" of amino acids is shorter (about five to 50 amino acids), it's a peptide. When it's longer (generally more than 50 linked amino acids) and more complex, it's a protein, according to WebMD and the Cleveland Clinic.

Our bodies utilize various types of peptides for many vital functions, including blood pressure regulation and digestion. Insulin, for example, is a type of peptide produced by the pancreas that controls our blood sugar. Peptides occur naturally in the body, but we also get them from the foods that we eat, like milk, eggs, legumes and oats, as previously reported by USA TODAY.

Similar to insulin, there are human-created, synthetic peptides that can be used to treat certain deficiencies or medical conditions. Some studies show certain peptides may have anti-inflammatory, anti-aging and muscle-building properties, making them popular in wellness circles.

You've likely seen advertisements for skincare products containing collagen peptides and nutrition supplements with creatine peptides, meant to restore skin elasticity and assist muscle building, respectively. Peptides are the broken-down, easier-to-digest versions of these naturally occurring compounds, making it possible for the body to absorb them into the bloodstream through a serum or pill.

While peptides have shown promise in these and other areas of health and wellness, the benefits and potential risks of some have been studied much more extensively than others. For example, there have been 50 years' worth of studies and developments on synthesized insulin, while Melanotan I and II, which are often used to enhance tanning effects, are less understood.

Why did the FDA restrict peptides in the past?

In 2023, the FDA banned compounding pharmacies (non-standard pharmacies that produce customized formulations for patients) from producing 14 specific peptides.

Compounding pharmacies do not receive the same FDA approvals for drug formulations as pharmacies that sell mass-produced drugs. They must still use only FDA-approved ingredients to make the formulations and are regulated by state and federal agencies, according to the FDA.

The banned peptides were identified as posing "potential significant safety risks" by the agency. Some were growth hormone-releasing peptides (GHRPs), which have become increasingly popular in fitness circles for their potential to stimulate growth hormone release and promote muscle building and repair.

Others were tested for use in appetite suppression or stimulation, wound repair, sleep regulation, anti-aging and immunity support, among other purposes. The FDA said none had a robust body of evidence to establish their efficacy, with multiple being tested sparingly on animals or in limited experimental capacities.

Potential adverse effects identified by the FDA in this 14-item list include heart toxicity, infections, pancreatitis, increased or decreased insulin sensitivity, serious immunoresponses, melanoma and death. In most cases, the FDA said there was not ample testing or evidence to prove the peptides were safe or effective for use in humans.

Still, these and other peptides have remained available online through yet another grey-area loophole. If the compounds are offered under the premise of "research," they are not subject to regulation, according to a paper published in April 2025.

Peptides, regulations and RFK Jr.

The push for peptides (both in injectable and non-injectable forms) has accelerated in recent years as influencers and manufacturers alike tout myriad benefits, many unsubstantiated by research. In a public meeting hosted by the FDA on Friday, March 27, the agency heard from dietary supplement makers, academics and patient advocates as it reconsidered its longstanding criteria for dietary supplements, as reported by the Associated Press.

Products that include peptides and promote unsupported claims technically already run afoul of FDA rules, FDA lawyers argued, but proponents of laxer rules said regulatory reconsideration for substances like peptides is long overdue.

Critics have likewise pointed out that RFK Jr. is a self-proclaimed proponent of peptides and has close ties to several vocal supporters and vendors of the compounds, including Gary Brecka and Dr. Mark Hyman, both of whom sell several products that say they contain beneficial peptides; and Brigham Buhler, a compounding pharmacy owner whom Kennedy previously hosted on his podcast.

Two of Kennedy's primary health advisers during his presidential campaign also included Calley Means, now a senior adviser in the HHS, and Trump's surgeon general nominee, Dr. Casey Means − both of whom have made hundreds of thousands of dollars selling and promoting supplements, probiotics and related wellness products, the AP reported.

Contributing: Reuters