Peptides: Miracle Molecules or Marketing Hype?

Peptides are everywhere in the healthcare zeitgeist. On social media, you’re likely to encounter an influencer claiming that injecting or ingesting peptides can improve your skin, build muscle,
increase focus or help you lead a longer and healthier life. Peptides are short chains of amino acids that are fundamental building blocks in protein and our bodies make them naturally. While some synthetic peptides like insulin and GLP-1s are widely used and approved, the off market use of other peptides have raised concerns among scientists. We’ll talk about the promise, dangers and hype of peptides.

Guests:

• Dhruv Khullar, physician at Weill Cornell Medicine; associate professor at Weill Cornell Medical College; contributing writer, The New Yorker
• Zara Stone, tech culture reporter, The San Francisco Standard

This is a computer-generated transcript. While our team has reviewed it, there may be errors.

Alexis Madrigal: Welcome to Forum. I’m Alexis Madrigal.

It is a brave new peptide world out there. In one remarkable scene from Dhruv Khullar’s article in The New Yorker, “Why Are People Injecting Themselves With Peptides?,” he relates how a doctor’s kid got injured in cross-country. Immediately his mom was like, “Oh, hey, Dad can inject you with peptides.” And the kid is like, “Absolutely not,” but is then convinced, and perhaps the injections even helped his healing.

Has the FDA approved a lot of this stuff? No. Are people doing it anyway, ordering stuff from labs somewhere in the world or from doctors who are actively promoting these off-label medical tactics? Yes, definitely. They definitely are, as we will hear.

So here to help us explore this strange new world of peptides, we’re joined first by Dhruv Khullar, who is a practicing physician at Cornell Medicine and an associate professor at Weill Cornell Medical College. His piece on peptides is in The New Yorker. Thanks so much for joining us.

Dhruv Khullar: So good to be with you.

Alexis Madrigal: So let’s just talk about the real basics of this. What is a peptide, and why are people hearing about them so much more right now than they were, say, five years ago?

Dhruv Khullar: Well, peptides are basically microproteins. So everyone’s heard about proteins, and they are strings of amino acids. If a string of amino acids is more than 50-ish long, then people tend to think of it as a protein. If it’s less than 50 amino acids or so, it’s a peptide.

And the human body actually makes thousands and thousands of peptides. So these things are in our bodies, and they’re circulating all over the place, and they send messages. They’re regulating systems inside the body.

Researchers have known about them for decades, and dozens of them have actually been turned into safe and effective drugs. So everyone’s probably heard about insulin. Insulin is a peptide. It moves sugar from your bloodstream into your cells.

These days, the most famous peptide is probably GLP-1, glucagon-like peptide-1, which, as we know, has all sorts of beneficial effects in the body.

So this is a really exciting area of science.

Now, what we’re talking about here is not any of these types of peptides, but unapproved peptides — peptides that have not gone through rigorous testing, that sometimes may have shown some interesting effects in mouse models or might have some theoretical reasons they might work.

These things have just exploded all over social media and online over the past couple years. They’re being marketed with basically claims of tremendous benefits — things like enhanced strength and better energy and more endurance, better recovery after you work out, even better tans or better libido.

So this is what we’re talking about. It’s a group of probably a dozen or so peptides that are really popular, and people are ordering them online and injecting them into their bodies.

Alexis Madrigal: Okay, Dhruv’s sold. Where do I get them?

No, I’m just kidding.

I am curious, though. How does this fit into our sort of theory of human biology? I think people oftentimes say, if you open a basic biology textbook, it’s like proteins are the body’s machines, you know, and things like that. Are peptides just the micro-machine version of this? Or do they have some other role in signaling and communication or something like that in the body?

Dhruv Khullar: So these are very small proteins. They’re called microproteins, so they’re primarily involved in signaling and regulation of other types of processes, although some of them can carry out processes by themselves.

If you think about insulin, it is signaling to the body that you should move some glucose, or sugar, from the bloodstream into cells.

There are all sorts of other peptides. Think about something like a growth hormone-releasing peptide that, as the name suggests, releases growth hormone. Growth hormone then carries out the effects that it does.

So some of these peptides do carry out activities themselves, but for the most part, scientists usually think about them as signaling molecules and regulatory molecules.

Alexis Madrigal: Why do people, generally speaking, inject these things?

People may know that from Ozempic, of course. Now there have been a million GLP-1 drugs that are being developed with different kinds of modes of ingestion. But why do people inject them?

Dhruv Khullar: Well, a lot of these peptides are broken down in the stomach. The stomach is a pretty hazardous environment for a lot of proteins and peptides. Stomach acid and digestive enzymes split these chains of amino acids into parts before they can actually enter the bloodstream and do what they’re supposed to do.

So when you inject them directly into your body, you can bypass that breakdown function of the stomach and get them directly where they need to go.

That’s the big idea around why. Even GLP-1s are injected. There are some oral versions of them that are not quite as effective, and the thought is that a lot of the peptide is being broken down and only a small proportion is actually getting into the bloodstream.

A similar thing is going on here.

Because people are injecting them, I think that also speaks to the idea that people are much more open to and comfortable with injecting things into their bodies because they’ve gotten so used to seeing people do it — or doing it themselves — over the past couple years with the rise of GLP-1 medications.

So now injecting these other compounds into their bodies might not seem as foreign as it did a decade ago.

Alexis Madrigal: Talk to me a little bit about the scientific background here. What’s the sort of potted history of this current generation of peptides?

Dhruv Khullar: Well, a lot of this has come out of very rigorous scientific work that was done maybe 20 or 25 years ago.

What scientists started to recognize was that, in the past, people thought a lot of these peptides were just fragments of larger proteins. So insulin is generated by the body as a much larger version of the molecule, and then it’s chopped up until you have the final version that goes around and does its work in the body.

One of the researchers I interviewed at UCLA, Pinchas Cohen, and others in his lab found that the genetic code actually codes for many more small microproteins, or peptides, than we initially thought.

There are all these parts of the genome that were previously thought of as junk DNA. We didn’t know what they did, but obviously, if 98% of your DNA is quote-unquote junk, it’s probably doing something. Evolution doesn’t conserve that type of thing.

What a lot of the so-called junk DNA was doing was encoding these other types of molecules.

So Cohen and others have discovered many, many peptides. Some of them have very interesting effects in the body, particularly in animal models.

For instance, there’s a peptide called MOTS-c, which in mice seems to help middle-aged mice run twice as long as mice that don’t take MOTS-c.

Cohen himself took it into Phase 1 clinical trials and ended up running out of funding before they were able to move it forward.

I want to make clear that there’s very interesting science behind a lot of these peptides. There’s also the potential for harm.

Another peptide Cohen discovered was something called Humanin. That was probably the first peptide discovered in this new age, and it also seemed really interesting in promoting longevity and reducing negative effects in the body.

Ultimately, though, it was found to be linked to certain types of cancer.

Those are the kinds of things that become apparent only when you study these compounds rigorously, which is why people shouldn’t simply inject themselves with peptides that haven’t been studied in the way we study other drugs.

Alexis Madrigal: How many of these peptides have been approved by the FDA for one thing but are now being used for something else, like the route that GLP-1s took? And how many really are just a researcher wrote a paper about them and people started synthesizing the drug?

Dhruv Khullar: Well, it’s both.

There are some peptides that have been approved for other conditions and are now being used off-label.

When we talk about off-label use of medications, that’s a very common thing doctors do. It means a drug was formally approved by the Food and Drug Administration for one indication, but doctors discover it also helps with other illnesses or conditions and prescribe it for those reasons. That’s totally accepted and done all the time.

So there are some peptides being used that way. Even then, though, we don’t always have the level of study we’d want before prescribing them for those other conditions.

One example is tesamorelin. It’s a growth hormone-releasing peptide that’s used to reduce abdominal fat, primarily in people who experienced side effects from HIV medications and developed excess abdominal fat.

Now people who don’t have HIV and haven’t taken those medications are starting to use it.

There are many other peptides that have nowhere near that level of evidence. They’ve shown promise in animal studies or theoretical work, and people are using those too.

People get them in all sorts of ways. You can order them online. Many come from overseas, primarily China. Some compounding pharmacies will prepare them and supply doctors’ offices, longevity clinics, or directly to patients.

Then there’s the other big area: research chemical companies. These companies make compounds for research purposes. They’re technically labeled “for research use only,” but they’ll often sell them to you, throw in some sterile water and a couple of syringes, and it’s kind of a wink-wink situation where everyone knows they’re actually being injected into people.

Alexis Madrigal: Big-picture question here, kind of setting up the next segment of the show. Does all this suggest to you that we need a new approach to drug regulation, or even medicine more broadly, to account for the fact that people want to use these substances even if they’re not sick, quote unquote?

Dhruv Khullar: I think this is a really open and interesting question.

Historically, medicine has been very good at treating disease. Someone gets sick, and we develop treatments.

To a lesser extent, medicine has been okay at prevention — trying to keep people from getting sick in the first place.

What medicine has had almost nothing to say about is optimization. And that’s what we’re talking about for a lot of people here.

People want peak performance. They want benefits related to longevity, even though those are very difficult to prove.

So I do think medicine needs to start thinking about how it can contribute to that conversation around optimization. Otherwise, it leaves a vacuum where other people are going to…

Alexis Madrigal: Well, that’s where TikTok comes in, no?

Dhruv Khullar: Yeah, exactly.

Alexis Madrigal: Dhruv Khullar is a physician as well as a contributing writer to The New Yorker. He’s got a piece there called “Why Are People Injecting Themselves With Peptides?”

We are talking about this world of peptides, and we’re going to turn in the next segment to peptide-tasting parties, clubs, and the kind of Silicon Valley-ization of all these things.

We want to hear from you. Have you explored or taken a peptide for an off-market use? What did you use it for? What are your questions about peptides, their dangers, and their health benefits more generally?

The number is 866-733-6786. That’s 866-733-6786, or email forum@kqed.org.

We’ll be back with more right after the break.