Men who eat higher amounts of dietary fat had significantly lower sperm production and concentration compared to men who had lower fat intake, according to findings from a new clinical study.

Researchers analyzed dietary and semen quality of 99 men, and found that sperm count and concentration were about 40 percent lower in men who consumed 37 percent or more of their daily calories as fat or 13 percent or more if the calories consumed consisted of saturated fat, compared to men with less fat intake.

About 71 percent of the participants were obese or overweight, and their sperm samples were collected from 2006 to 2010 at Massachusetts General Hospital Fertility Center in Boston.

"Notably, the frequency of overweight and obesity among men in this study does not differ much from that among men in the general population in the USA at about 74 percent," the researchers pointed out.

 The men were asked how often they ate specific foods in the past year, and men who reported most fat consumption had about 43 percent fewer sperm and 38 percent lower sperm concentration than those in the lowest fat intake group. 

However, researchers found that men who ate more omega-3 fatty acids, commonly found in some fish and plant oils had higher concentrations of normal-shaped sperm in their semen samples. 

About 15 percent of couples are affected by infertility, and men’s health issues are actually responsible about 40 to 60 percent of the time, researcher said.  While previous studies have shown associations between obesity and fewer healthier sperm, the latest research looked into specific types of fats consumed among overweight people and how it affected their fertility.

"Given the limitations of the current study, in particular, the fact that it is a cross-sectional analysis and that it is the first report of a relation between dietary fat and semen quality, it is essential that these findings be reproduced in future work," lead author Dr. Jill Attaman of Dartmouth-Hitchcock Medical Center in Lebanon and her research team wrote. 

Experts have previously known of several other lifestyle factors that are associated with male infertility like smoking, heavy marijuana use, alcohol intake, cocaine use, and exposure of the testes to heat, but few have looked into the impact of diet on men’s reproductive potential, the authors wrote. 

"The magnitude of the association is quite dramatic and provides further support for the health efforts to limit consumption of saturated fat given their relation with other health outcomes such as cardiovascular disease," said Attaman in a news release.

The study was published on Tuesday in the journal Human Reproduction.