WEDNESDAY, Oct. 24, 2012 — Instead of reaching for a condom, try drinking a few glasses of milk. According to a new study from the Harvard School of Public Health, men who consume three portions of dairy a day experience poorer sperm quality.

Though many fertility studies focus on the impact diet can have on a woman's ability to conceive, concern is increasing over the effect a man's lifestyle and nutrition may have on his ability to produce healthy sperm.

Harvard scientists analyzed the diets of 189 fit, healthy men between the ages of 19 and 25 who participated in at least an hour and a half of exercise per week. The men filled out questionnaires in which they recorded the frequency with which they consumed dairy, fruit, meat, and other foods. An ounce of cheese (28g), a teaspoon of cream, a scoop of ice cream, or a glass of full-fat milk all constitute one portion of dairy.

The researchers also analyzed the shape and speed of sperm in the men, discovering that study subjects who ate more than three full-fat portions of dairy per day had a 25 percent reduction in sperm quality when compared to those who ate less dairy.

Researchers believe that estrogen, the female hormone found naturally in cows' milk, is responsible for the men's potentially lackluster ability to reproduce. "The association could be attributed to the high levels of naturally occurring reproductive hormones in commercial dairy products," said Myriam Afeiche, Harvard research fellow and study leader, according to the U.K.'s Daily Mail.

She raised the possibility that pesticides found in dairy may also have an impact on male fertility. "It is also possible that the presence of other compounds in dairy such as pesticides, chlorinated pollutants, and heavy metals could account for this relation," added Afeiche.

However, Allan Pacey, MD, fertility expert at the University of Sheffield and Chairman of the British Fertility Society, told the Daily Mail that men shouldn't stop eating dairy in response to this study. He stresses that even though sperm quality and fertility may wane, dairy consumption doesn't ultimately affect the ability to conceive. "Although it goes down, it doesn’t go into the red," said Pacey.

Previous studies have linked impaired fertility in men to excessive carbohydrate ingestion and obesity.

The dairy study was presented at this week's 68th annual meeting of the American Society for Reproductive Medicine. Other research discussed at the meeting shows a link between diet and in vitro fertilization in women, specifically that lower carb intake seems to improve in vitro success.