Saturated fats, like those found in cheeses and meats, may do more than weigh men down after a meal – a Danish study also links them to dwindling sperm counts.
Researchers found that young Danish men who ate the most saturated fats had a 38-per-cent lower concentration of sperm, and 41-per-cent lower sperm counts in their semen, than those who ate the least fat.
"We cannot say that it has a causal effect, but I think other studies have shown that saturated fat intake has shown a connection to other problems and now also for sperm count," said Tina Jensen, lead author of the research.
For their study, published in the American Journal of Clinical Nutrition, the researchers examined 701 young Danish men who were about 20 years old and getting checkups for the military between 2008 and 2010.
Participants were asked about the food they ate over the prior three months, then asked for a semen sample. The researchers broke the results into four groups, depending on how much of the men's energy intake came from saturated fats, and compared how much sperm the men in each group produced.
The men who got less than 11.2 per cent of their energy from saturated fats had an average sperm concentration of 50 million per millilitre of semen and a total sperm count of about 163 million. That compared to 45 million sperm per millilitre of semen and a 128 million count in men who got more than 15 per cent of their energy from saturated fats.
The World Health Organization defines anything over 15 million sperm per millilitre of semen as normal. In the study, 13 per cent of men in the lowest-fat group and 18 per cent of men in the highest-fat group fell below that level. Jensen said her team's findings may partially explain studies that have found sperm counts decreasing around the world.