By Rebecca Jones

In a wonderful example of modern day evolution, scientists have discovered that large quantities of junk food can make young men infertile even if they are otherwise healthy.

According to two new studies conducted by fertility doctors from Harvard University, University of Rochester and the University of Murcia, Spain young men between the ages of 18 and 22 who consumed large amounts of junk food, especially those with trans fat, had poorer quality sperm even if they were in good shape, exercised regularly and had no other reproductive system problems.

Researchers analyzed the sperm of hundreds of men and found that those that ate junk food had sperm that were less likely to survive long enough to successfully fertilize an egg. Their sperm was also found to contain higher levels of trans fat and to be in lower concentration than in those who steered clear of junk food.

According to one of the projects lead author Audrey J. Gaskins, “the main overall finding of our work is that a healthy diet seems to be beneficial for semen quality.”

“Specifically, a healthy diet composed of a higher intake of fish, fresh fruit, whole grains, legumes and vegetables seems to improve semen mobility,” she goes on to say, “which means a higher number of sperm actually move around, rather than sit still.”

188 participants filled out questionnaires that allowed researchers to categorize their diets as either “Western” which meant red meat, refined carbs, energy drinks and processed sweets or “Prudent” meaning mostly unprocessed foods like fish, vegetables and whole grains. The sperm of these men was analyzed to determine movement, concentration and shape.

Regardless of factors such as race, weight or habits like smoking the men categorized as having a “Western” diet were found to have sperm with reduced movement. Sperm shape and count however remained the same.

Researchers warn that this is only preliminary research and more work needs to be done before any definitive conclusions can be drawn but all signs point to a correlation between a healthy diet and better quality sperm count. Survival of the fittest or just another case of “you are what you eat”?