Sperm count alone is a poor predictor of whether you'll conceive because sperm can be damaged at the molecular level even when numbers look normal. What matters more is quality, specifically motility, morphology, and DNA fragmentation, since intact, functional sperm are what actually get the job done.
I've spent more time than I care to admit reading studies on male fertility. Not because I'm a doctor—I'm not. But because the numbers are staggering, and the standard advice doesn't match the evidence. Global sperm counts have dropped more than 50% over the last 50 years. That's real. A 2017 meta-analysis in Human Reproduction Update looked at 185 studies and nearly 43,000 men. The decline was consistent across North America, Europe, Australia, and New Zealand. If you were born in the 1970s, your father likely had twice the sperm count you do.
But here's what most fertility blogs skip: count alone is a poor predictor of whether you'll conceive. You can have a "normal" count—15 million per milliliter or higher—and still struggle because the sperm themselves are damaged at the molecular level. A 2018 study in Andrology found that over 40% of men with unexplained infertility had high sperm DNA fragmentation. That means the genetic material inside the sperm head is broken. Even if the sperm reaches the egg, it can't fertilize it, or if it does, the embryo stops developing.
The real question isn't "How do I increase my sperm count?" It's "How do I make my sperm actually work?"
The Problem With Counting
The WHO still defines normal sperm concentration as 15 million per milliliter. But that number was set in 2010, and it was based on a population of men who were already showing signs of decline. A man in the 1940s would have averaged 100 million per milliliter. Today, the average is around 50 million—and dropping.
Dr. Shanna Swan, an epidemiologist at Mount Sinai, has called this "the silent pandemic." Her 2021 book Count Down argues that if the current trend continues, the median sperm count could hit zero by 2045. That's not a prediction—it's a linear projection. The body doesn't work in straight lines, but the direction is clear.
The problem is that most "increase sperm count" advice targets the wrong lever. Maca root, zinc supplements, and avoiding hot baths might nudge a number upward by a few million. But if the sperm coming out are damaged, a higher count of broken sperm doesn't help.
Sperm quality is measured by three things:
- Motility — can they swim forward?
- Morphology — are they shaped correctly?
- DNA fragmentation — is the genetic material intact?
Of these, DNA fragmentation is the strongest predictor of pregnancy success. A 2012 meta-analysis in Human Reproduction Update found that men with high DNA fragmentation had significantly lower pregnancy rates through both natural conception and IVF. The number of sperm didn't matter as much as the percentage of intact ones.
What Actually Damages Sperm Quality
The environment you live in matters more than any supplement. The testicles are exposed to whatever you eat, breathe, and touch. And modern life is full of chemicals that directly attack sperm.
Phthalates and BPA
These endocrine disruptors are everywhere. Plastic food containers, receipts, personal care products, the lining of canned foods. A 2014 study in Environmental Health Perspectives measured phthalate metabolites in urine and found that men in the highest quartile had 20% higher DNA fragmentation compared to the lowest. BPA is worse. A 2010 study in Fertility and Sterility showed that men with higher urinary BPA had lower sperm concentration, lower motility, and higher DNA damage.
The mechanism is straightforward: phthalates and BPA mimic or block testosterone signaling in the Leydig cells of the testicles. Less testosterone signal means poorer sperm production at the quality level.
Microplastics and PFAS
This is newer and more unsettling. In 2024, researchers at the University of New Mexico tested 23 human testicles. Every single one contained microplastics. Polyethylene—the plastic used in grocery bags and food wrap—was the most common. The concentration was three times higher than what they found in canine testicles from the same region.
PFAS (perfluoroalkyl substances), used in non-stick pans, waterproof clothing, and fast-food wrappers, are also linked to lower sperm quality. A 2024 study in Toxicological Sciences reported that men with higher PFAS levels had significantly lower sperm counts and higher DNA fragmentation. These chemicals don't just sit in the body. They generate oxidative stress, which directly breaks sperm DNA.
Heat
You've heard that heat kills sperm. It's true in the short term. Testicles hang outside the body because they need to stay about 4°C cooler than core temperature. A 2019 study in Reproductive Biology and Endocrinology found that scrotal heating through hot baths or saunas temporarily increased DNA fragmentation. But the effect reversed within weeks.
The real problem isn't the occasional sauna session. It's chronic low-level heat—sitting in a car for 8 hours a day, wearing tight synthetic underwear, having a desk job where your thighs are pressed together. That's a steady state of thermal stress. A 2015 study in Occupational Medicine found that men who sat for more than 6 hours per day had significantly lower sperm quality than men who moved regularly.
What the Research Says About Fixing It
The evidence points to a few concrete actions. None of them are complicated. Most of them cost nothing.
Stop eating out of plastic.
This is the single biggest lever you can pull. A 2019 intervention study in Environment International asked men to switch to glass or stainless steel food storage for just three days. Urinary BPA levels dropped measurably. Do the same for water bottles—if you're drinking from plastic that's been sitting in a hot car, you're drinking heated plastic. Switch to glass or stainless steel.
Eat to protect sperm from oxidation.
Sperm are unusually vulnerable to oxidative stress. Their membranes are packed with polyunsaturated fatty acids, which rust easily. A 2022 meta-analysis in Advances in Nutrition found that men with higher dietary intake of antioxidants had better sperm motility and lower DNA fragmentation.
The foods that show up consistently in the research:
- Oysters and pumpkin seeds (zinc)
- Brazil nuts (selenium, two a day is enough)
- Fatty fish like salmon (CoQ10 and omega-3s)
- Citrus or bell peppers (vitamin C)
I'm not giving supplement dosages—that's for a doctor. But these foods are easy to add.
Sleep seven hours.
A 2020 study in Journal of Sleep Research followed 1,000 men and found that those who slept fewer than six hours per night had 25% higher sperm DNA fragmentation than those who slept seven to eight hours. Cortisol, the stress hormone, directly suppresses testosterone production. Less testosterone means lower quality sperm.
Cut alcohol and tobacco.
You know this. But the numbers are worth repeating. A 2016 study in Reproductive Biology and Endocrinology found that men who smoked had 14% higher DNA fragmentation than non-smokers. Alcohol above two drinks per day increased oxidative stress markers. If you want clean sperm, keep alcohol to a couple of nights a week and quit cigarettes entirely.
The Sauna Question
Since Oakman is built around sauna, let me address it directly. Does regular sauna use hurt sperm quality? The short answer: not if you do it right.
The Finnish data is reassuring. Finnish men sauna 4 to 7 times per week on average. Finland also has one of the highest birth rates in Europe. That alone suggests that moderate, intermittent heat exposure doesn't cause permanent damage. A 2018 study in Andrology exposed men to 20-minute sauna sessions at 80°C twice a week for three months. Sperm quality dipped slightly during the intervention but returned to baseline within six weeks after stopping.
The key is intermittent. Chronic, constant heat is the problem. A 15- to 20-minute sauna session, followed by cooling down, does not stress the testicles in a way that causes lasting harm. If you're actively trying to conceive, you could take a break from sauna for a month before trying—or just time your sessions so you're not sauna-ing daily in the weeks leading up to ovulation. But for general health, the cardiovascular and heat shock protein benefits likely outweigh any temporary dip.
What You Can Do Starting Tomorrow
Forget the "10 superfoods to boost your fertility" lists. They're mostly filler. Here's the short version of what the research supports:
- Get a real sperm analysis. Ask your urologist for a DNA fragmentation index (DFI). Under 15% is excellent. Over 30% means you have work to do.
- Ditch plastic food storage. Use glass. Don't microwave in plastic. Don't drink from bottles that have been in a hot car.
- Eat zinc-rich foods. Oysters, pumpkin seeds, beef. Two Brazil nuts a day for selenium.
- Sleep seven hours. No shortcuts.
- Move your body. If you sit all day, stand up every hour. Walk. Strength train. Don't let your scrotum cook.
- Keep alcohol moderate. Two drinks, max, a few nights a week.
These aren't "hacks" or "biohacks." They're basic environmental hygiene. The research is clear that the modern world is damaging sperm at a fundamental level. You can't avoid every chemical, but you can choose which ones get into your body.
The sperm count myth is that more is better. The truth is that functional, intact sperm matter more than raw numbers. Quality beats quantity every time. And cleaning up your exposures—plastic, sleep, food—is something you can start doing today without a pill, a protocol, or a prescription.
Frequently asked questions
what is sperm DNA fragmentation and why does it matter
Sperm DNA fragmentation means the genetic material inside the sperm head is broken. Even if a fragmented sperm reaches the egg, it may fail to fertilize it, or the resulting embryo may stop developing. A meta-analysis in Human Reproduction Update found that men with high DNA fragmentation had significantly lower pregnancy rates through both natural conception and IVF.
does plastic really affect sperm quality
Yes, the evidence is pretty clear. A study in Environmental Health Perspectives found that men in the highest quartile of phthalate exposure had 20% higher sperm DNA fragmentation than those in the lowest. BPA, found in food container linings and receipts, was linked to lower sperm concentration, lower motility, and higher DNA damage. Switching to glass or stainless steel food storage measurably lowered urinary BPA levels in just three days in one intervention study.
does using a sauna hurt sperm quality
Intermittent sauna use doesn't appear to cause lasting harm. A study in Andrology found that twice-weekly sauna sessions caused a slight dip in sperm quality during the exposure period, but levels returned to baseline within six weeks of stopping. The bigger concern is chronic, low-level heat from habits like sitting for long periods each day, which a study in Occupational Medicine linked to significantly lower sperm quality.
how much sleep do you need for healthy sperm
The research points to seven to eight hours as a meaningful target. A study in Journal of Sleep Research following around 1,000 men found that those sleeping fewer than six hours per night had 25% higher sperm DNA fragmentation than men who hit that range. Cortisol, the stress hormone, directly suppresses testosterone production, and less testosterone leads to lower quality sperm.