Supplements are “like a religion” for Pachi Paris, a 29-year-old from Miami who works in finance. So when he and his wife started trying to conceive last year, it felt only natural that he started taking pills meant to boost his fertility, to the tune of $250 per month.

Six months later, “we found it odd that she's not pregnant yet,” Paris said. “We both got a workup done, and it turns out that I was one that had some health issues going on with my sperm.” That came as a surprise, given Paris is young, works out, and has a healthy diet—but he’s hardly alone.

Beyond taking fertility supplements, men are going to increasingly extreme lengths to optimize their sperm health. They’re icing their testicles, avoiding pornography, and monitoring their semen’s “vitality scores” as part of the so-called sperm-maxxing trend.

While many sperm-maxxing influencers offer classic wellness misinformation—no, you don’t need to replace all your briefs with organic cotton boxers to keep cool down there—and many biohackers are relying on unproven metrics, the trend has an unexpected upside: a large male audience is newly interested in their reproductive health. It comes just as researchers are making the case that men’s well-being plays a key role in fertility—as well as pregnancy health and early child development.

“I'm encouraged anytime the spotlight shifts to male fertility,” says Michael Eisenberg, a professor of urology at Stanford University. “I think it's been underappreciated for a long time … [and] fertility is a team sport.”

Infertility, or the inability to conceive after a year of trying, affects about one in six people worldwide. Reproductive health has long been seen as women’s territory, given women bear the physical burden of pregnancy. While some studies suggest male factors cause an estimated 30 percent to 50 percent of infertility cases, men are not evaluated in roughly one in four cases.

Men’s health plays a role in whether a pregnancy ends in miscarriage, the mother suffers from preeclampsia—a potentially life-threatening pregnancy complication—or the baby is born with birth defects, though the overall risks are low. Sperm carry epigenetic marks that are sensitive to a man's environment before conception, meaning lifestyle choices can affect sperm health.

That’s where sperm-maxxers come in, tracking their sperm count, motility (the sperm’s ability to swim to the egg), morphology (the sperm’s shape and size), and DNA fragmentation. It takes roughly two to three months for a new sperm to fully mature, so lifestyle changes to improve sperm health can quickly yield results.

While some viral accounts suggest men eat lots of beef, butter, and raw milk, studies show that diets high in saturated fats are tied to lower sperm count, which makes pregnancy less likely. The Mediterranean diet, rich in omega-3 fatty acids, antioxidants, and fiber, is associated with better sperm quality, including sperm count, motility, and morphology.

Research also points to environmental toxins, such as endocrine-disrupting chemicals and microplastics, as potential culprits of male infertility. Prolonged exposure may cause oxidative stress—an imbalance in the body between antioxidants and unstable molecules known as free radicals, leading to cell damage—which can reduce sperm motility and viability.

Longevity influencer Bryan Johnson famously (or infamously, depending on your perspective) posted last month about allegedly ridding his semen of microplastics and the steps he took. Some of them are just good environmental advice—getting rid of plastic cutting boards, for example—but for fertility-minded men, there are other steps that are likely more important.

“There are easier things to worry about before microplastics—lose weight, exercise, and stop smoking, either weed or tobacco,” says Jesse Mills, a urologist and director of the Men’s Clinic at UCLA.

Self-medication won’t necessarily improve sperm health, either, and it could cause harm in some cases. Some sperm-maxxers tout testosterone because of its role in sperm production—but testosterone therapy can potentially hinder that process and may reduce fertility. Meanwhile, in a randomized clinical trial, considered the gold standard in medical research, men taking zinc and folic acid supplements did not have significantly better semen quality or higher birth rates than those taking placebos.

“Supplements probably can’t hurt,” Mills says. But he noted that many studies on their health benefits are industry-sponsored, meaning their findings may be exaggerated.

Studies suggest obesity, smoking, excessive drinking, either insufficient or too much exercise, poor sleep, stress, and repeated (and multiple sources of) heat exposure—from saunas or hot tubs, for example—can all affect sperm health.

“It’s the boring things that count: eat, move, sleep,” Mills says of sperm health.

Age matters, too. Sperm quality tends to decline as men get older, raising the risk of pregnancy complications, birth defects, autism, and schizophrenia. Yet paternal age doesn’t get nearly as much attention as the risk of women conceiving later in life, says Jonathan Huang, a reproductive endocrinologist at the University of Hawaii at Mānoa.

There are still major gaps in the research on men’s reproductive health, and many studies have limitations such as small sample sizes or studies done only in mice. The evidence is also generally stronger on how preconception health affects fertility than it is on pregnancy outcomes and child health, though that is starting to change.

“Lots of those studies have been performed in men with established reproductive problems from the start,” says Tim Moss, a science communicator at Healthy Male, a men’s health nonprofit in Australia. “The extrapolation from somebody who's gone to a fertility service provider to get help, they are very different from the majority of people who have not done that.”

Men are left to navigate the scientific ambiguity in an online ecosystem that promises clear answers and solutions, often for a price. For Paris in Miami, the real answers came from hormone tests and a semen analysis, which pointed to low morphology, or misshapen sperm. Some experts argue that morphology tests aren’t good predictors of fertility, but that clue led to Paris’ eventual diagnosis: varicoceles, or enlarged veins in the scrotum that are similar to varicose veins in the legs and one of the most common causes of male infertility. He had corrective surgery in February.

“Men my age, they think they're doing everything right by not drinking, eating clean, getting regular exercises in, but [they] still can have things going on internally that they have no idea about,” Paris says. He’s been sharing his experience online to encourage other men to get hormone and semen tests done when they start trying for a baby rather than waiting a year for an infertility diagnosis. He still credits the supplements with boosting his health overall.

Mills and Eisenberg both approve of hopeful dads proactively learning about their sperm quality—and say men who aren’t looking to conceive anytime soon could also benefit from semen analysis.

“As we get less healthy, we do see that reflected in semen parameters,” Eisenberg says, making sperm a kind of “sixth vital sign.” He’s now also chief medical adviser for SwimClub, a men’s fertility supplement company that launched last year. The supplements include around 15 ingredients, including fish oil—which research shows could improve sperm quality—but also others with unproven benefits like zinc and folate, and those with mixed findings such as coenzyme Q10.

Even when men are following solid medical advice—and not using red-light therapy on their testicles, another unproven hack sperm-maxxers are pushing—experts say they should keep their expectations in check. Achieving a healthy pregnancy involves a degree of randomness, and men who bank too much on sperm optimization risk falling into self-blame and guilt.

“If we're just going to reduce men's fertility to the simple idea that you maximize your sperm count, and that's what you need, then we’re doing a disservice to those men,” Moss says.