A study of men attending a U.S. fertility clinic found those with the fattiest diets produced significantly less sperm. Their sperm density was also lower.

The research also showed that diets high in omega-3 fatty acids, found in fish and plant oils, were associated with improved sperm quality.

Men were divided into three groups according to how much fat they consumed. Compared with those eating the least fat, men with the highest fat intake had a 43% lower sperm count and 38% lower sperm concentration. Sperm concentration, or density, is defined as the number of sperm per unit volume of semen.

Men consuming the most omega-3 fatty acids had 1.9% more correctly formed sperm than men with the lowest intake.

Lead scientist Professor Jill Attaman, from Harvard Medical School in Boston, said, "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."

The findings are reported in the journal Human Reproduction.

More work is needed to confirm the findings, say the researchers who acknowledge that their small study involving just 99 men was limited.

Eating a fatty diet did not appear to impair the fertility of any of the men in the study. None had sperm counts or concentrations below the "normal" levels of at least 39 million and 15 million per milliliter.

Leading British fertility expert Dr Allan Pacey, senior lecturer in andrology at the University of Sheffield, said, "This is a relatively small study showing an association between dietary intake of saturated fats and semen quality. Perhaps unsurprisingly there appeared to be a reasonable association between the two, with men who ate the highest levels of saturated fats having the lowest sperm counts and those eating the most omega-3 polyunsaturated fats having the highest."

 From the March 15, 2012, Prepared Foods' Daily News.