Men trying to conceive should lay off the bacon, a Harvard University study suggests.
Researchers looked at 156 men struggling to conceive, examining their diets and size and shape of their sperm. Overall, those who consumed more than half a portion of processed meats every day showed significantly lower levels of "normal" sperm when compared to those eating less than half a portion daily.
Men who consumed the most dark meat fish, such as salmon and tuna, exhibited a total sperm count about 34 percent higher than men who ate the least amount of fish.
Finally, sperm shape was better among those who ate the most white meat fish, such as cod, compared to those who consumed the least.
"What brought up our concern is how meat is produced in the United States," Dr. Jorge Chavarro, one of the researchers, told New York Daily News. "Many beef producers give cattle natural or synthetic hormones to stimulate growth, a few days or weeks before the animals are killed. We wanted to examine how these hormones might affect people who consume them."
However, the study is not without its critics. Among them is Dr. Allan Pacey, chairman of the British Fertility Society.
"The relationship between diet and men's fertility is an interesting one, and there is certainly now convincing evidence that men who eat more fresh fruit and vegetables have better sperm than men who don't," Pacey told Medical Daily. "However, less is known about the fertility of men with poor diets and whether specific foods can be linked to poor sperm quality."
The study was presented at the American Society for Reproductive Medicine's 2013 Annual Meeting in Boston.