Put down that wheel of brie, young man. That is, if you're thinking of having a baby.
New research conducted at the Harvard School of Public Health in Boston has found that men who eat three portions of full-fat dairy a day have lower quality sperm than those who do not, reports the Daily Mail.
The team compared the diets of 189 men aged 19 to 25, none of whom were overweight and all of whom exercised regularly. Fit young lads, to be sure. They had each man fill out a detailed questionnaire about exactly how much and how often they ate certain foods, including dairy, fruit, meat and other food types.
Then they examined each man's sperm, looking at it's shape, how fast it could travel, and other markers that indicate fertility.
Their results are sure to displease many a dairy farmer. They found that men who ate more than three servings of full-fat dairy a day had sperm of 25 per cent poorer quality than those who did not.
A portion of dairy for the purposes of the study included an ounce of cheese (28g), a teaspoon of cream, a scoop of ice cream or a glass of full-fat milk.
Though it has been hypothesized in the past that dairy could affect male fertility, this is the first study to support that assertion.
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Lead author of the study Myriam Afeiche has a few ideas about why dairy might be impeding the fertility of the men who consumed it in higher quantities.
"The association could be attributed to the high levels of naturally occurring reproductive hormones in commercial dairy products," Afeiche tells the Daily Mail. "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."
According to the government website Assisted Human Reproduction Canada, about 8.5 per cent of couples of reproductive age experience infertility. Though we often think of infertility as a woman's issue, the inability to conceive a child is due to male factors 30 per cent of the time.
There are a number of proven causes of male infertility, including genetics, hormone inbalances, STIs, absence of sperm, previous cancer treatment or a reproductive tract blockage, and there are many dietary recommendations for men trying to conceive, but this is one of the first studies of its kind to suggest such a definitive correlation between sperm quality and dairy.
So again men, unhand that brie.