Peptides are a hot topic in conversations about wellness right now. Promoted by health and fitness influencers and widely available online, they are touted for benefits ranging from boosting immunity to speeding muscle recovery.
But how much of that is backed by science? And what do people with cancer need to know about peptides?
Larry Norton, MD, a breast medical oncologist at Memorial Sloan Kettering Cancer Center (MSK), says there are good reasons to be skeptical. “We don’t know what these products actually do in the body, because there have not been appropriate scientific experiments,” he explains.
Here’s what is known — and what remains unknown — about peptides and your health.
What are peptides?
Peptides, like proteins, are strung-together amino acids, which are the fundamental building blocks of the human body. While peptides form short chains, generally consisting of up to 50 amino acids, proteins are much longer, typically containing several hundred amino acids.
Both peptides and proteins act as chemical signals in the body, helping to regulate the function of our cells.
Are there any FDA-approved drugs that are made of peptides?
Yes, and you’ve likely heard of many of them. Widely used peptide-based drugs include:
- Insulin
- Growth hormones
- GLP-1 agonists (drugs like Ozempic and Wegovy)
- Hormone-blocking medications that treat hormone-driven cancers like prostate and breast cancers
“Importantly, these peptide drugs are prescribed by doctors and have passed scrutiny to prove they are safe and effective for people with certain medical conditions,” says Dr. Norton, who is Senior Vice President in the Office of the President at MSK and Medical Director of the Evelyn H. Lauder Breast Center. “This is not the same situation as some of the newer peptides, which are being promoted without rigorous evidence to support their use.”
What’s different about the newer peptides being promoted?
Many of these products make broad, vague claims — that they “boost” the immune system, increase energy, or speed muscle recovery — without much scientific evidence to back them up.
“To verify such claims, a peptide would need to be rigorously tested in the lab and then in controlled clinical trials with adequate follow-up time to look for longer-term side effects,” Dr. Norton says. “That foundational research is limited for many of the products currently being marketed.”
Clinical trials are considered the gold standard for determining whether a treatment is safe and effective in humans.
“Trials are a very well-developed process for determining the safety and efficacy of chemicals that are put into the body,” Dr. Norton adds. “Until these peptides are evaluated using this scientifically rigorous process, there are just too many questions about how they work — both their possible benefits and their dangers.”
What could be the harm in taking wellness peptides?
Beyond the lack of scientific and clinical evidence, there are real questions about the quality and safety of peptides.
There are a lot of things we don’t know about how these compounds are manufactured, stored, and shipped, Dr. Norton says. Depending on how they are transported, they could lose their effectiveness in transit. They also could contain harmful impurities.
These products, which are frequently sold online, may be injected or taken as nasal sprays, skin creams, or powders mixed into drinks. These delivery methods can also carry risks.
Dr. Norton says another concern is that people may be tempted to take peptides to alleviate symptoms of what might turn out to be a serious health condition, delaying the diagnosis of the underlying issue.
Are there special considerations for people with cancer?
“We don’t really know,” Dr. Norton says, “because what many of these compounds actually do in the body and how they affect cells remains an open question.” For example, some peptides claim to treat inflammation and promote wound healing — which could possibly impact the growth of cancer cells.
People experiencing the effects of cancer and its treatment may be drawn to claims about products that can boost energy levels, promote healing, or reduce stress and anxiety. It’s important that patients with these concerns speak to their care team about the best way to cope with side effects, rather than ordering untested products online.
At MSK, the Integrative Medicine and Wellness Service offers complementary treatments that address many of these concerns, including acupuncture, herbal medicines, and mind-body therapies.
What do regulators say about peptides?
An outside advisory committee of the U.S. Food and Drug Administration (FDA) recently voted to recommend adding several wellness peptides to the list of products available at compounding pharmacies. (These pharmacies mix or combine raw drug ingredients to create personalized medicines.)
Those who voted to grant this permission to compounding pharmacies argued it would be a safer means to access the drugs, rather than ordering them from unregulated, risky sources on the internet.
Opponents say opening the door for compounding pharmacies to make peptides would mistakenly give them the appearance of legitimacy.
The FDA has not made a final ruling on whether to allow this practice to go forward. Dr. Norton cautions that even an FDA decision to allow compounding is not the same thing as an FDA approval based on rigorous clinical trials.
What is the bottom line on peptides?
“These are potentially potent substances that could have both short-term and long-term harms,” Dr. Norton says. “Any peptide that has a positive effect can also have a negative effect.”
For example, when someone with diabetes takes the proper dose of insulin, it controls their disease. But if they take the wrong dose, or if someone without diabetes takes it, it could be fatal.
“With these products, there are too many questions about safety,” he says. “Until these products are properly studied, the risks are too great to ignore.”
Key takeaways
- Unlike FDA-approved peptide drugs such as insulin and GLP-1 agonists, wellness peptides being sold online lack the rigorous clinical trial evidence needed to demonstrate they are safe and effective.
- Beyond unproven claims, wellness peptides carry real safety risks, including unknown manufacturing quality, potential harmful impurities, and the danger of delaying the diagnosis of a serious underlying health condition.
- People with cancer should be especially cautious, because the effects of these compounds on cancer cells remain unknown, and some peptides that claim to promote healing or reduce inflammation could potentially impact the growth of tumors.
- Even if the FDA decides to allow compounding pharmacies to produce wellness peptides, that decision does not carry the same weight as a formal FDA approval based on rigorous clinical trials.
Dr. Norton holds the Norna S. Sarofim Chair in Clinical Oncology.