Too much junk food may lower sperm count

Linked to levels of saturated fats

If you're thinking of starting a family, it may be time to cut back on the hot dogs and fries, as a new study has found that eating too much fatty food can lower a man's sperm count.

Men who ate the most fatty foods had the lowest sperm counts compared with those who ate the least, researchers from Harvard Medical School found.

But the study also found that men who ate healthier foods with more omega-3 fatty acids, the type of fat often found in fish and plant oils, had more and "better formed" sperm.

Harvard researchers questioned 99 men about their diet and analysed their sperm samples over a four year period.

The men were the divided into three groups according to how much fat they consumed in their diet.

Compared with those who ate the least fat, those with the highest fat intake had a 43 per cent lower total sperm count and 38 per cent lower sperm concentration.

Men who consumed the most omega-3 fats had slightly more correctly formed sperm than men with  the lowest omega-3 intake.

When researchers looked at the types of fat consumed by the men, they found that sperm quality was most affected by the amount of saturated fat in their diet.

Despite having poorer quality sperm, men who ate the most fatty foods still had sperm counts and concentrations which fell within the normal range.  

Professor Jill Attaman, who led the research, said the study had some limitations. Some 71 per cent of the men in the study were overweight or obese, which could affect sperm quality, and only a single sperm sample for each man was collected during the study.

And while the study shows a link between saturated fat consumption and poorer sperm quality, it does not prove that saturated fats are the cause of this.

Prof Attaman 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.

"In the meantime, if men make changes to their diets so as to reduce the amount of saturated fat they eat and increase their omega-3 intake, then this may not only improve their general health, but could improve their reproductive health too."

British fertility expert Dr Allan Pacey, of the University of Sheffield, commented on the study: "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.

"Importantly, the study does not show that one causes the other and further work needs to be carried out to clarify this. 

"But it does add weight to the argument that having a good healthy diet may benefit male fertility as well as being good general health advice."

The study is published in the journal Human Reproduction.

Family GP