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What’s driving sperm counts down globally?

What’s driving sperm counts down globally?

Recent studies show that sperm counts have declined ~60% over the past 40 years

Here at Poplin, we are not a fan of fear-mongering. However, sperm counts are declining. It’s real; it’s happening; it matters. And, as engaged health advocates, we want you to be informed...and empowered to do something about it.  

Why is this happening? 

Nobody knows for sure, but there are several compelling theories. We’ve split them into 3 main categories: body, mind and environment. 


  1. Poor nutrition: Like its impact on many other areas of your health, eating a poor, imbalanced diet can impair your fertility. A poor diet can affect your blood sugar levels, your nutrient levels and your inflammation levels, just to name a few. All of these can interfere with sperm quality. Not surprising, healthier diets have been shown to improve sperm parameters (e.g., sperm count, sperm concentration, sperm motility) in men with poor semen quality. 
  2. Unhealthy BMI: One recent meta-analysis confirmed that there is a direct correlation between obesity and BMI; specifically, sperm count fell 2.4% for every 5 unit increase in BMI. Based on this, we can anticipate that increased body mass index has a negative effect on sperm quality. Relatedly, diabetes, which is often present alongside an elevated BMI, can also impact sperm health. However, it is also important to note that both morbid obesity and being underweight have a negative effect on sperm quality. As is often the case with health, it’s a Goldilocks phenomenon - not too little, not too much…just right. Normal body weight is the best foundation for fertility. 
  3. Exercise: A recent study showed that exercise improved semen quality and reproductive hormone levels in sedentary obese adults. There are probably several reasons for why this is the case, but they probably include increased cardiovascular capacity, increased antioxidant capacity and improved blood sugar profiles. One cautionary note here: long-distance cycling has proven to be one of the few exercise modalities that can decrease sperm count. 
  4. Smoking: This one is pretty straightforward - tobacco smoking is associated with decreased semen quality. In this study, in particular, smokers had significantly lower semen volume, sperm concentration, sperm motility, total sperm count, sperm morphology, free testosterone and follicle stimulating hormone, compared with non-smokers. 
  5. Excess alcohol consumption: One study found that sperm concentration, total sperm count and percentage of spermatozoa with normal morphology were negatively associated with increasing habitual alcohol intake. In other words, the total number of sperm and the proportion of healthy sperm decreased as alcohol intake increased. Interestingly, in several animal studies, we see that this negative impact is compounded if there is also diabetes present. Alcohol consumption in diabetic mice can intensify sperm chromatin/DNA damage and alcohol further deteriorates sexual dysfunction in diabetic rats. Diabetes + excess alcohol consumption = impaired sperm. 


  1. Increased stress: Elevated, chronic stress levels impact semen volume and semen quality. In one study, the number of "healthy" sperm was significantly reduced in stressed men compared to reference values. That same study found that the number of "healthy" sperm was significantly higher after stress therapy, indicating a recovery of sperm quality. You can manage your stress levels and get sperm moving and shaking again. 


  1. Endocrine disruptors: Endocrine-disrupting chemicals, often found in personal care, home care and food products, have been shown to negatively impact male fertility. One study showed that endocrine-disrupting chemicals (EDC’s) increased oxidative stress, increased mitochondrial dysfunction, increased DNA damage and decreased sperm motility and viability. Moreover, an epidemiological study showed a small increased risk of male reproductive disorders following prenatal and postnatal exposure to some persistent environmental chemicals classified as endocrine disruptors but the study authors believe that more evidence is needed. 
  2. Environmental exposures: In addition to endocrine disruptors, certain heavy metals, solvents and fumes have also been associated with semen impairment. Outdoor air pollution has also been shown to impact semen quality, though the order of magnitude is unclear. Controlling your exposure level is key here. 
  3. Electromagnetic radiation: Studies have found that radio frequency electromagnetic radiation emitted from cell phones may impact sperm concentration. The same may be true of wireless Internet use and sperm count. More research is clearly needed here. In the meantime, let’s just be practical - get the phone out of your pocket and the laptop off of your lap. 
  4. Medications: Certain medications, such as PPI’s and SSRI’s, may impact sperm quality. These are some of the most commonly prescribed drugs in the US, so it is up to you to talk to your doctor if you are planning to get pregnant soon. 
  5. Occupational exposures: Certain physical risk factors are associated with sperm anomalies, such as mechanical vibrations, excess heat and extended sitting periods. Mechanical vibrations can originate from machinery or motorcycles; excess heat can originate from saunas, steam rooms or hot tubs, for example. And, extended sitting periods often come from desk jobs. Again, control your exposures as best you can.

This is what we already know. There is also a lot that we still don’t understand or haven’t fully unpacked yet. For example, there are suggestions that male sperm production capability is influenced while in utero; this is definitely an area ripe for exploration. However, based on the above factors, there are many things that you can do today to positively impact your sperm health. 

Interestingly, many of these factors are the same ones that interfere with a woman’s fertility. If you are in a heterosexual relationship, instead of going it alone on your quest to upgrade your body, we’d encourage you to enlist your man’s help in getting healthy together. It will benefit you, your partner and your future baby.