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Your Favorite Briefs Might Be Cooking Your Sperm, Says a 26,836-Man Study
A new study of 26,836 men links tight underwear to weaker semen numbers and nearly double the sperm DNA damage. Here's the twist, and how to keep things cool.
The underwear drawer just became a crime scene
Picture it. You're getting dressed, you reach for the snug boxer briefs that make your butt look like a personal achievement, and somewhere a urologist quietly sighs. That's roughly the energy of a new study out of China, which looked at 26,836 men and asked the one question nobody asks on a first date: what are you wearing under there? The answer, it turns out, might matter more than your waistband's brand name. But before you throw your entire drawer into a bonfire, stick around. There's a twist, and it's a good one.
26,836 men, one question: what's under the jeans?
According to ScienceAlert, researchers led by urologist Xue-Chun Hu at the University of Science and Technology of China published the work in the Asian Journal of Andrology. It's being called the largest study yet on tight underwear and sperm quality. The setup was simple. Men coming in for fertility checks at the university's First Affiliated Hospital reported what they had worn most often over the past three months. Loose meant boxers. Tight meant Y-fronts, thongs and boxer briefs. That split the group into 21,221 loose-underwear guys and 5,615 tight-underwear guys, with a median age of 30. Then the lab coats came out, and the numbers got spicy.
The numbers your boxer briefs don't want you to read
After adjusting for other health factors, the tight-underwear group had 18 percent higher odds of producing less semen, ScienceAlert reported. It gets louder from there. Tight underwear was linked to 12 percent higher odds of fewer swimmers that actually swim, 48 percent higher odds of fewer normally shaped sperm, and 108 percent higher odds of more sperm with DNA damage. In plain numbers, high DNA damage showed up in 10.7 percent of the tight-underwear men versus 5.8 percent of the loose crowd. Nearly double. From fabric. The researchers also noticed that trouble getting or staying "up," and finishing faster than planned, were more common in the tight group. The authors' main suspect is heat. Your body keeps that area a few degrees cooler on purpose, and a tight waistband basically turns it into a sauna with no exit. "Choosing loose underwear may represent a simple, modifiable approach to help protect semen quality and sexual function," the authors wrote.
Plot twist: correlation is not a conviction
Here's where we put the pitchforks down. This study can't prove tight underwear causes any of this, and ScienceAlert is clear about that. Every man in it was already seeking a fertility assessment, which means he may not look like the average guy scrolling this article. The bedroom findings were described as preliminary and to be read with caution. And it's not the only study in town. ScienceAlert notes that a 2022 study of 3,041 couples in the US and Canada found little evidence that the chance of actually getting pregnant was tied to tight underwear or heat around the scrotum. Biomedical scientist Tim Moss, writing for Healthy Male back in 2022, warned that these studies are "usually conducted in groups of men who are seeking help for fertility problems, so you can't generalize the results to the whole population." So your briefs are not under arrest. They are a person of interest.
NOCTI's take: Nobody is coming for your favorite briefs
We love a good waistband. We love a man who feels hot in what he's wearing. That confidence is real, and it's not going anywhere. But here's the honest part. Most men will spend 20 minutes choosing underwear for a date and zero minutes thinking about what's happening inside them for the other 364 days of the year. That's not a fashion problem. That's a priorities problem. You don't have to pick between hot and healthy. Rotate. Save the snug pair for the moments that count, and let the boys breathe the rest of the time.
Keep it cool: 5 moves that cost less than a new pack
Mayo Clinic says some research suggests that when the scrotum gets too warm, it may lower the body's ability to make sperm, and that loose underwear, sitting less, and skipping saunas and hot tubs may improve sperm quality. Here's how to turn that into a routine. 1. Rotate your drawer. Looser boxers for long workdays, flights and sleep. Snug styles for the gym, the date or the photo. 2. Stand up more. Mayo Clinic lists sitting less as one way to keep things cooler. Set a reminder to move every hour. 3. Go easy on the hot tub and sauna if you're trying for a baby. Your future kid will forgive you for skipping the steam room. 4. Protect the rest of the system. Mayo Clinic also points to a healthy weight, managing stress, not smoking, limiting alcohol and preventing STIs as ways to support healthy sperm. Regular STI testing is part of that, no shame attached. 5. Know when to see a doctor. Mayo Clinic says if a pregnancy hasn't happened after a year of sex without birth control, it may be time to get checked. A fertility specialist can find the cause and talk treatment.
The bottom line (and the waistband line)
Your underwear won't ruin your life, but it might be one of the easiest health upgrades you'll ever make. Want care that fits the man you are, from your skin to your recovery to your health? Explore it on your terms at joinnocti.com/discover. This article is for general information and isn't medical advice.
SourcesScienceAlert, Asian Journal of Andrology +1 more
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