December 20, 2023, 2:10 pm | Read time: 4 minutes
There are various factors that can affect sperm quality in men: smoking, stress, and poor diet. However, a series of studies has revealed another, previously overlooked reason for the decline in sperm quality.
In the male testes, sperm are formed from stem cells–millions are produced daily. To assess sperm quality, doctors use metrics such as sperm count (the total number of sperm), their concentration, and motility, meaning their movement. But sperm concentration is on the decline. A global study reaches a devastating conclusion: Sperm quality has been decreasing for 50 years, and the pace seems to be accelerating.
Overview
Global Study Shows Sperm Quality Has Been Declining for 50 Years
A meta-analysis published in the journal “Human Reproduction Update” that evaluated the results of 223 studies from 53 countries shows that sperm quality has been on a downward trend worldwide for 50 years.1 The average sperm concentration dropped from 101.2 to 49.0 million per milliliter between 1973 and 2018, a decline of 51.6 percent. Sperm is considered healthy if it contains at least 15 million sperm per milliliter.2 Additionally, during the same period, the sperm count fell from 335.7 to 126.6 million (-62.3 percent). A healthy ejaculate should contain more than 39 million sperm.
Particularly concerning is the fact that the decline in sperm concentration is accelerating: While scientists observed an annual decline of 1.2 percent from 1972 to 2018 until the year 2000, the rate of decline after 2000 was already 2.6 percent per year.
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People Are Surrounded by a “Chemical Cocktail”
Sperm quality is influenced by a variety of factors: An unbalanced diet, obesity, and the consumption of tobacco and alcohol can have negative effects. Stress and diseases such as diabetes also affect semen quality.
However, that’s not all: Various studies reveal that exposure to different chemicals we encounter in everyday life also impairs male fertility.
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Unhealthy Chemicals Hide in Everyday Items
A study with urine samples from 98 Danish men examined the impact of 29 chemicals found in commonly used plastics on semen quality.3 It shows that the tolerable levels of chemicals associated with deteriorating sperm quality are exceeded many times over.
The substance Bisphenol A (BPA), found in items such as storage containers and water bottles, has the greatest impact. To reduce BPA exposure in the population, the European Food Safety Authority (EFSA) has recommended a 20,000-fold reduction in the tolerable BPA content in the European Union.4
However, the study authors emphasize that simply avoiding BPA is not enough, as the potential harm from other chemicals studied is also significant, such as polychlorinated dioxins, Bisphenols S and F, and the phthalate DEHP.
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Known Painkiller Reduces Sperm Concentration
In the Danish study, urine samples from five participants showed elevated paracetamol levels. These were further analyzed separately by the research team. Their risk for poor semen quality was significantly above the average of all participants overall. After BPA, paracetamol was the second most important factor affecting sperm concentration, according to the study authors.
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Pesticides in Food Have Negative Effects
A systematic review of 25 studies concludes that exposure to pesticides leads to lower sperm concentration.5 Specifically, the study compared the sperm concentration of men exposed to higher and lower amounts of organophosphates (OPs) and methylcarbamates. It found that men with higher exposure had a 30 percent reduced sperm concentration. People ingest pesticides through contaminated food and water.
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How to Improve Sperm Quality
Some measures are already clear: Quit smoking, skip the after-work beer, or reduce everyday stress. Exercise also has a positive impact on sperm quality and count. An international study showed that men who exercise regularly and extensively have healthier sperm than those who are less physically active.
Diet is another possible lever: Fruits, vegetables, zinc-rich foods like oatmeal, and fish oil can improve sperm quality. Surprisingly, even tomato paste is beneficial for fertility.
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