Unexplainable - A period piece

Episode Date: June 24, 2026

Periods and menstrual fluid have long been overlooked by scientists. Now, researchers are starting to suspect they might be sources of medical treasure. (Originally aired in 2024) Guest: Jemma Evans, biologist For show transcripts, go to ⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠vox.com/unxtranscripts⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠ For more, go to ⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠vox.com/unexplainable⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠ And please email us! ⁠⁠⁠[e-mail]⁠⁠⁠ We read every email. Support Unexplainable (and get ad-free episodes) by becoming a Vox Member today: ⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠vox.com/members⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠ Thank you! Learn more about your ad choices. Visit podcastchoices.com/adchoices

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We're working on this huge new project, and we're going to be able to share more about that soon. But over the next two weeks, while we're getting ready, we're going to play you some of our favorite episodes. Each of us chose an episode we love, and I wanted to share one from my co-host, Bird Pinkerton. I still think about it all the time, because just imagine there was this substance that might have super healing powers. Then imagine it wasn't rare, that billions of people could just make it on their own. We'd obviously be researching something like that as much as we possibly could, right? Right?

Here's bird. Let's say you fall off your bike and you hurt yourself. So the skin cells on your arm or your leg, for example, have been scraped off or torn apart, and you're bleeding because the blood vessels underneath them are torn. How does your body heal itself? Well, first of all, the blood clots and forms a scab, and then once the scab forms, the very top layer of skin cells gets busy. The cells come in, they multiply,

and they basically quilt together underneath the scab to form a new top layer of skin. All of this over the course about two to three weeks. And this trick that our skin can pull off, it seems pretty impressive. Until you compare it to a different part of the human body. This tissue that is of particular interest to a biologist named Gemma Evans,

because it kind of turbocharges this entire process. This amazing tissue, the endometrium in the uterus. The uterus, of course, is the womb, and the endometrium is its lining, the sort of safe, nurturing space for a fetus to hang out. So every month, the uterus builds lining up, and then if no fertilized egg shows up, it flushes all that work away,

kind of like sloughing off layers of skin. So the endometrium creates a wound, essentially. It basically tells itself, to be destroyed roughly every 26 to 35 days. But it also tells itself to repair. As soon as a piece of the uterus lining, the endometrium starts to be shed,

the section, sort of next to it, gets an instruction to start repairing it. That top layer of cells growing back happens as soon as an adjacent area has fallen off. It heals not in two to three weeks, like the rest of the body, but in three to five days. And usually, it heals.

without scarring. So normally when the body does kind of a rush job like this, it has to make some sacrifices. It can build up scar tissue instead of regular skin, and that scar tissue can't always do what the original tissue could do. In the case of the endometrium, though, the repaired tissue is just like the original. This process is so quick and so impressive that I got Jemma and some of her colleagues thinking. We thought, hmm, this is absolutely fascinating. What can this teach us about other parts of the body. Can we harness those properties? If she could harness those properties, it could potentially help a lot of people. Diabetics whose wounds heal really slowly, people who have vascular diseases, even patients with burns.

So this is unexplainable. I'm Bird Pinkerton. And this week, Gemma Evans tries to figure out if there's a way to translate the uterus's superhealing powers to the rest of the body. Does your life change once a month because of your period? Oh, what a disaster. Let me tell it to you straight. Unexplainable can change the way you feel about your period. You wouldn't think so, but it's wonderful. Fabulous.

I call it just plain smart. Now that's something. Remember, there's a feeling with... Unexplainable. It can actually change the way you feel about your period. Going into all this, Gemma had a big hunch. Because the healing that's happening in the uterus is happening while the uterus is bathed in menstrual fluid, this stuff that we also call period blood,

that is basically sort of a super complex mixture of tissues and proteins and cells and other stuff. And so, Jemma's hunch, was that menstrual fluid might be what's helping the uterus heal so fast. And also that menstrual fluid could help other wounds heal faster too. That's essentially what we're looking at. It seems really simple. You know, you think, doesn't this just make sense? Like, isn't it obvious? but not very obvious because nobody else surprisingly had tried it.

Maybe it's the yuck factor, but that's the basic hypothesis of what we were doing. To test this basic hypothesis, Gemma had to find some menstrual fluid. And because it's understudied, there wasn't like an established protocol for collecting it as a fluid, but she found some volunteers who were willing to use menstrual cups and give her the contents. The initial stage then was to just test the theory. you know, would menstrual fluid actually have any effect on repair? Jemma and her colleagues, they couldn't just go around putting menstrual fluid on people's wounds. So instead, they made a simplified version of a wound in the lab.

They took cells from the top layer of human skin and then grew them in trees. And then they made a little hole in that, quote unquote, skin to simulate a wound and finally put menstrual blood on the holes. The first time we did the experiment, we actually thought we'd got it wrong. Gemma says they came back the next day and the holes were gone. We thought, what on Earth has happened here? We clearly didn't make the holes in the cell layer because we can't find any holes. They hadn't made a mistake here. They really had made the holes.

It's just... They'd repaired that quickly. They wound up trying again. We thought, okay, right, we've got to repeat this, but we'll look at them a bit more frequently. And this time, it really was clear that something in the menstrual fluid was healing skin cells in less than 24 hours. Their control groups were healing more slowly. Like, it really was the menstrual fluid making the difference.

It was one of those eureka moments where you think, is this real? I just need to do it a few more times to actually check if it's real because it doesn't feel like this can, it can be this simple. Science can be kind of a frustrating process with a lot of dead ends, kind of unclear results. But this experiment was a pretty strong signal, that, like, yes, this hypothesis was right on.

But they still tried more experiments. Like, they got real skin from plastic surgery patients to see how that healed. And they ran tests on living pigs as well. Researchers made one millimeter wounds on pig skin and then put menstrual fluid on those wounds. Pigs are very similar to human when it comes to skin. It's why tattoo artists practice on pigs.

And they're the best or the most appropriate model for human equivalent skin research. In these experiments, the results were not quite as dramatic. Like, there wasn't the same kind of 24-hour turnaround time for healing. And especially in the pig experiments, they were only able to check the wounds every few days because the wounds had to be dressed. But once again, the researchers did find evidence

that the menstrual fluid helped with healing. This is ideal, like a bunch of experiments, lots of promising results. There's just one small problem. on. To be completely frank, people are not going to want to put menstrual fluid on their skin. Okay, in the interest of fact-checking, there was a TikTok trend for a while where people were using period blood as a face mask. But regardless of vampire facials or whatever they're called, we're not going to get away from that ick factor. And to be clear, like, this ick factor makes sense, right? Like putting bodily fluids directly on your open wounds. probably not the best idea, which is why, as she was running these experiments on skin and pigs,

Jemmo's also working on another investigation, an investigation into how exactly menstrual fluid was working its healing magic. Support for this show comes from Vetch Pet Insurance. Do you have a pet? Every six seconds, a pet owner in the U.S. gets hit with a vet bill of over $1,000. And it's almost always an unwelcome surprise. That's where Fetch Pet Insurance comes in. Fetch is the most complete pet insurance. Get paid back up to 90% of vet bills.

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19 plus to wager. Ontario only. Please play responsibly. If you have questions or concerns about your gambling or someone close to you, please contact connects Ontario at 1-866-531-2,600 to speak to an advisor. Free of charge. BetMGM operates pursuant to an operating agreement with Eye Gaming Ontario. Gemma Evans had seen that if you put menstrual fluid on wounds, they heal faster.

And she also knew that putting menstrual fluid directly on wounds was, probably not a real option. So we started, I guess, to actually try to dig down and understand what's different about menstrual fluid. What's the actual, I guess, magic factors in the menstrual fluid that might be helping with this repair. To figure this out, Jemma turned to a lab that does something called proteomics, where they basically analyze substances and tell you what kind of proteins are in them. And Jemma wanted this lab to tell her just a little more about the basic ingredients of menstrual fluid. So she gave them a bunch of normal blood as kind of like a baseline to compare to, and then she gave them some of the menstrual fluid samples that she'd

collected. The proteomics team actually asked us, what's this wacky second fluid you've given us? Because we've never seen this number of differences between two samples before. We've never had a sample that has this level of complexity. Menstrual fluid, as it turns out, has way more going on than normal blood running through our veins and arteries. It has lots of proteins that are not found in that normal blood. So Jemma picked a couple of proteins that seemed especially promising. She ran some more tests. And again, the results seem to suggest that some of these proteins just on their own might help speed up tissue repair.

So these were more exciting results, like lots of promising ideas to pursue further. Except you can't find wound healing medicines based on Gemma's work out in the world today, in part because she didn't get to pursue these ideas further. Essentially, it comes down to the funding environment. So Australia, US, globally, the funding environment is really,

really tough. If you look at the numbers for the NIH in the U.S., for example, it only funds about 20% of the applications it gets for new research grants. And those are the numbers for all types of research science. Like reproductive health is especially underfunded within that. And then within reproductive health, menstruation science is extra ignored. Like one paper I looked at found that over the span of a decade, there are about 15,000 research papers with references to semen. and about 400 papers referencing menstrual blood. And, like, the simplest explanation for this seems to be that, historically, a lot of scientists were men,

and they just didn't want to investigate menstrual blood because it was considered gross and kind of taboo, or because they just weren't interested. So there hasn't been the same kind of scientific infrastructure and interest built up around menstruation as there has around other routine human processes. And Jemma says she saw this in her day to day. One thing I found very early in my research career was nobody else was talking about menstruation at scientific conferences even.

Now, to be clear, when she reflects on her efforts to get more funding for this particular project, Jemma does not think that like some Australian funding panel got the ick from menstrual fluid and refused to fund her work because of it. She says that skin treatments were especially hard to get funded. And that was probably part of the problem. And also, she thinks that just the idea of using proteins for menstrual fluid was maybe just too new. Getting funding to progress the research for something which was entirely novel, nobody else had ever done this before. Even though we had a wealth of data to support us, it was almost a leap too far for funding bodies because this was very blue skies.

As it was, Gemma and her colleagues looked for funding in a bunch of different places, couldn't find it. And then I made that decision in the end to leave research. I absolutely loved research. It was amazing. But getting that funding to pay your salary, pay the salary of your team and pay for the research itself, it gets really hard at the end of the day. And I think that's why we lose a lot of good researchers. She does clinical trial work now instead. You know, anybody who's in research and particularly biomedical research where the ultimate goal for biomedical research is to improve people's lives.

That's why we do what we do in biomedical research. It is mentally really challenging to walk away from that. I don't want to end on total doom and gloom, though, especially because things are kind of changing around menstruation and menstrual fluid. Like, as I was reporting out this story and talking to people, they kept saying that, yes, menstrual fluid, has been seen as trash historically, like something to be disposed of. But in the last decade or so, people started doing a lot of really cool,

really interesting menstrual fluid research. People are realizing that menstrual fluid is kind of a treasure. And sure, like, progress is slow, and this particular example of promising research hit a funding snag. But this doesn't have to be the end of the story. Like, even if Jemma isn't the person who pursues this, she has put the initial research out into the world. And now, maybe someone else out there can keep exploring where she left off. I hope in the future somebody does pick it up and run with it because I think there is some significant opportunities there for, you know, not necessarily someone who's just fallen over and grazed their knee because what schoolchild hasn't done that.

But somebody who has an extensive burn wound or is in the military and is injured in battle and needs to heal a wound very, very quickly, somebody who has a health condition, which makes them more likely to have an infection in a wound or more prone to wounds full stop. I would hope that somebody would see the value in that and pick it up and run with it. And I think the whole overarching principle of what we were doing was gaining treasure from the trash. This episode was produced and reported by me, Baird Pinkerton. It was edited by Jorge Just and Brian Resnick. Meredith Hodnott runs the show.

Noam Hassamfeld, composed the music. Christian Ayala did the mixing and the sound design. Melissa Hirsch did our fact-checking. And Manding Nguyen is the fact that loggerhead strikes impale their prey on little spikes and save it for later. If you want to read more about periods before then, though, I have two book recommendations. The first is Kate Clancy's, book Period, which talks about Gemma's research and so much more. And then the second is Leah Hazard's

womb. I actually first heard about Gemma's research in Leah's book, and I spoke to her about it, and also about other exciting period science. We have a Q&A on the site from that conversation. Thanks also to Linda Griffith, who took some time to talk to me about this science, and to Rachel Gross, the author of Vagina Obscura, who helped me think through this episode. And finally, a huge, huge thank you to Lois Salamanson, who used to run the lab that Gemma worked at, and just took a lot of time to help me understand this story. If you would like to support the show and the journalism that Vox does, we would love it if you would become a member.

It is very easy to do. Just go to Vox.com slash members, and you will get access to all of Vox's journalism, but you will also know that you are supporting all of Vox's journalism. And for those of you who have emailed to let us know that you signed up because of Unexplainable, Thank you. And thank you to those of you who have left us a nice review on your podcast platform or told someone in your life about the show. You are all excellent. Unexplainable is part of the Vox Media Podcast Network. And we will be back very soon with another episode about everything that we do not yet know.