Young men can protect their fertility by keeping testicular temperature low, eating a diet rich in fruits, vegetables, fish, and whole grains, getting regular moderate exercise, sleeping seven to eight hours a night, limiting alcohol, avoiding tobacco and cannabis, and reducing exposure to endocrine-disrupting chemicals found in everyday plastics.
Let's start with a number that should get your attention: Between 1973 and 2018, global sperm counts dropped by more than 50 percent, according to a 2022 meta-analysis in Human Reproduction Update. The decline is accelerating. For men born after 1980, the average sperm concentration is now below what researchers consider optimal for fertility.
Here is what that means for you: If you plan to have biological children someday, waiting until you are ready to start a family is not a strategy. The choices you make in your twenties and thirties directly affect your fertility in your forties and beyond. The good news is that most of the factors driving the decline are things you can control.
This is not about panic. This is about understanding how your body works and making a few adjustments while the adjustments still matter.
Your testicles are temperature-sensitive organs
Sperm production requires a temperature about 3 to 4 degrees Fahrenheit below core body temperature. That is why your testicles hang outside your body. When that temperature rises, sperm quality drops.
The research is clear: men who use hot tubs or saunas for 30 minutes per week for three months show a measurable decrease in sperm count and motility. A 2018 study in Andrology found that sperm concentration dropped by about 50 percent in men who used wet saunas twice weekly for three months. The good news is that the effect is reversible. Sperm production cycles every 64 to 72 days. Stop the heat exposure, and your numbers typically return to baseline within three months.
What you can do now:
- Limit hot tub and sauna sessions to 15 to 20 minutes. If you are a regular sauna user, consider alternating between sessions and breaks.
- Keep your laptop off your lap. A 2011 study in Fertility and Sterility found that men who used laptops on their laps for one hour had scrotal temperatures rise by 2.5 degrees Celsius.
- Wear loose-fitting underwear when you are not working out. Boxers are better than briefs for temperature regulation. A 2018 study from Harvard found that men who wore boxers had 25 percent higher sperm concentrations than men who wore briefs.
- Avoid long bike rides on narrow seats without breaks. The combination of heat and pressure can temporarily reduce sperm quality.
What you eat directly changes your sperm quality
Your diet affects your fertility within weeks, not years. Sperm are produced continuously, and their quality reflects your nutritional status over the previous two to three months.
A 2019 systematic review in Nutrients found that men who ate diets high in processed meats, full-fat dairy, and trans fats had lower sperm counts and motility. Men who ate diets rich in fruits, vegetables, fish, and whole grains had higher sperm quality across the board.
Specific nutrients that matter:
Zinc is essential for sperm formation. Oysters are the classic source, but pumpkin seeds, beef, and chickpeas also deliver. A 2020 meta-analysis in Nutrients found that zinc supplementation improved sperm quality in men with low baseline levels.
Selenium supports sperm motility. Brazil nuts are the most concentrated source. Two Brazil nuts per day cover your selenium needs.
Omega-3 fatty acids improve sperm membrane integrity. Fatty fish like salmon, mackerel, and sardines are the best sources. A 2018 study in Andrology found that men who ate fish regularly had better sperm morphology than men who did not.
Vitamin D levels correlate with sperm motility. A 2017 study in European Journal of Endocrinology found that men with adequate vitamin D levels had higher sperm motility than men who were deficient. Get your levels checked. If you are low, sun exposure or a supplement can fix it.
Antioxidants matter because sperm cells are vulnerable to oxidative damage. Berries, dark chocolate, walnuts, and leafy greens all help. A 2019 Cochrane review found that men who took antioxidant supplements (vitamin C, vitamin E, coenzyme Q10) had higher live birth rates, though the evidence was moderate.
What you can do now:
- Eat fish twice per week.
- Add a handful of walnuts and a serving of berries to your daily diet.
- Eat zinc-rich foods regularly.
- Get your vitamin D levels checked at your next physical.
Exercise improves fertility. Overtraining hurts it.
Moderate exercise improves sperm quality. A 2017 study in Reproductive Biology and Endocrinology found that men who exercised at moderate intensity for at least 150 minutes per week had higher sperm counts and motility than sedentary men.
But there is a limit. Endurance athletes who train at high volume for years sometimes show reduced sperm quality. A 2014 study in Sports Medicine found that elite endurance athletes had lower sperm concentrations than recreationally active men. The mechanism appears to be a combination of heat buildup during prolonged exercise and hormonal changes from chronic training stress.
Strength training is fine. Heavy lifting does not hurt fertility. The concern is specifically about long-duration endurance exercise without recovery.
What you can do now:
- Aim for 150 minutes of moderate exercise per week.
- If you are a serious endurance athlete, take recovery days seriously. Overtraining suppresses testosterone and increases cortisol, both of which reduce sperm quality.
- Do not exercise in tight, non-breathable shorts for hours at a time.
Sleep is when your body makes sperm
Testosterone production happens primarily during sleep. A 2011 study in JAMA found that men who slept fewer than five hours per night for one week had a 10 to 15 percent drop in daytime testosterone levels. Since testosterone drives sperm production, poor sleep directly affects fertility.
A 2020 study in Journal of Sleep Research found that men with sleep disorders had significantly lower sperm counts and higher rates of DNA fragmentation in their sperm. DNA fragmentation is a measure of how damaged the genetic material inside your sperm is. High fragmentation reduces the chance of successful pregnancy and increases miscarriage risk.
What you can do now:
- Sleep seven to eight hours per night consistently.
- Keep your bedroom cool. Above 75 degrees Fahrenheit can interfere with both sleep quality and testicular temperature regulation.
- Reduce screen time 60 minutes before bed. Blue light suppresses melatonin, which can delay sleep onset and reduce sleep quality.
Alcohol, tobacco, and cannabis have real effects
Alcohol consumption has a dose-dependent relationship with sperm quality. A 2019 study in Andrology found that men who drank more than 25 units of alcohol per week (about 12 to 15 standard drinks) had lower sperm counts and more abnormal sperm morphology than men who drank less. Binge drinking was particularly harmful.
Tobacco is worse. A 2016 meta-analysis in Reproductive Biology and Endocrinology found that smokers had 13 percent lower sperm counts than non-smokers. The effect was stronger in heavy smokers. The chemicals in cigarette smoke damage sperm DNA directly.
Cannabis is more complicated. The endocannabinoid system plays a role in sperm function, and regular cannabis use appears to reduce sperm count and motility. A 2019 study in Human Reproduction found that men who used cannabis weekly had 28 percent lower sperm counts than non-users. The effect was reversible after stopping.
What you can do now:
- Keep alcohol to moderate levels. Two to three drinks per week is fine. Binge drinking is not.
- If you smoke, quit. The effect on fertility is measurable and reversible.
- If you use cannabis regularly, consider reducing frequency if fertility is a future goal.
Environmental toxins are real, and you can reduce exposure
Microplastics, phthalates, BPA, and PFAS chemicals are everywhere. They are in food packaging, water bottles, non-stick pans, and even clothing. These compounds are endocrine disruptors, meaning they interfere with hormone signaling in your body.
A 2024 study from the University of New Mexico found microplastics in every human testicle they examined. Polyethylene, the plastic used in grocery bags and food packaging, was the most common. The concentration was three times higher in human testes than in dog testes from the same region. The study did not prove causation, but the correlation raises serious questions.
Frequently asked questions
does sitting in a hot tub or sauna affect sperm count?
Yes, and the research is specific. A 2018 study in Andrology found that sperm concentration dropped by about 50 percent in men who used wet saunas twice weekly for three months. The good news is the effect is reversible, since sperm production cycles every 64 to 72 days and counts typically return to baseline within three months of stopping heat exposure.
what foods are best for male fertility?
A 2019 systematic review in Nutrients found that men who ate diets high in processed meats, full-fat dairy, and trans fats had lower sperm counts and motility, while men who ate fruits, vegetables, fish, and whole grains had higher sperm quality. Specific nutrients worth paying attention to include zinc, selenium, omega-3 fatty acids, vitamin D, and antioxidants like vitamin C, vitamin E, and coenzyme Q10.
how does sleep affect sperm production and fertility?
Testosterone production happens primarily during sleep, and a 2011 study in JAMA found that men who slept fewer than five hours per night for one week had a 10 to 15 percent drop in daytime testosterone levels. A 2020 study in Journal of Sleep Research found that men with sleep disorders had significantly lower sperm counts and higher rates of sperm DNA fragmentation, which reduces the chance of a successful pregnancy.
does cannabis use lower sperm count?
Regular cannabis use does appear to reduce sperm count and motility. A 2019 study in Human Reproduction found that men who used cannabis weekly had 28 percent lower sperm counts than non-users. The effect was reversible after stopping use, so reducing frequency matters if preserving fertility is a future goal.