However, the study from Harvard Medical School in the US, found those with a diet rich in healthy fats like omega 3 and omega 6, found in food groups like fish and nuts, had healthier and more active sperm.
Saturated fat is found in processed bacon, sausages and ham, dairy and butter, while mono-unsaturated fat is found in items such as olive oil.
The study divided a group of men into three, according to their saturated fat intake.
It found that men in the group with the highest saturated fat intake had 41 percent fewer sperm than those in the lowest, reports the Daily Mail.
The findings were presented at the American Society for Reproductive Medicine conference in Denver.
Jill Attaman, who led the study, said: "We were able to demonstrate that for men who took in higher amounts of saturated and mono-unsaturated fat, there was an association with decreased sperm concentration.
"But polyunsaturated fat - those seen in fish primarily - was associated with improved sperm morphology and motility."
Morphology relates to the size and shape of the sperm and is an indicator of fertility.
