A recent study has put cheese and high fat dairy products in the crosshairs when it comes to poor sperm quality: as few as three slices of cheese may make young men less likely to enjoy fatherhood.

Scientists from Harvard School of Public Health in Boston, US, demonstrated that full-fat dairy foods, even small amounts, may have substantial adverse effects on male fertility. They observed poorer sperm quality in men whose daily diet included at least three portions of full fat dairy. One portion was defined as 28 grams of cheese, a teaspoon of cream, a 250ml glass of whole milk or a scoop of ice-cream.

Study details

The study population comprised of 189 healthy young men, aged 19 to 25. The subjects were fit and had a normal body weight— they all exercised for at least one and a half hour per week.

A survey was used to compare their dietary intake: participants self-reported their usual weekly intake of dairy products, meats, fruits, and vegetables amongst other foods. Moreover, semen samples were collected from each subject to examine key components of male fertility, namely sperm shape and speed.

Study findings

The scientists observed a 25 percent reduction in sperm quality in men whose consumption of high-fat dairy products exceeded three portions a day compared to those who ate less.

The connection

Myriam Afeiche, study leader, explained that “the association could be attributed to the high levels of naturally occurring reproductive hormones [cows’ oestrogen] in commercial dairy products,” according to the Daily Mail. It is this oestrogen which appears to decrease fertility in men. Afeiche also raised the plausibility that pesticides, chlorinated pollutants and heavy metals, which tend to accumulate in dairy fats, could also impede healthy sperm production.

Implications of the study

Dr Allan Pacey, fertility expert at the University of Sheffield and Chairman of the British Fertility Society, told the Daily Mail that men need not renounce on dairy merely because of this study’s findings. He emphasised that, although consumption of dairy products may diminish sperm quality and fertility, dairy foods do not cause infertility.

“Although it goes down, it doesn’t go into the red. A change of that magnitude for a man in a fertility clinic, we wouldn’t worry about that,” Dr Pacey told the Daily Mail.

This study, one of the first to imply such a definitive association between sperm quality and dairy, was presented at the 68th annual meeting of the American Society for Reproductive Medicine.

Diet and male fertility

Other studies also suggest a link between diet and male fertility. For instance, a previous study by the same researchers correlated a high carbohydrate intake to diminished sperm count; probably because of the increased likelihood of obesity (and the resulting altered hormonal equilibrium) in the young men. Moreover, fad diets, overly restrictive diets or any extreme dietary changes may affect sperm count which may take months to get back to normal levels. Heavy alcohol consumption, smoking, and use of anabolic steroids can also decrease sperm production.


    Afeiche et al (2013) Dairy food intake in relation to semen quality and reproductive hormone levels among physically active young men. Hum Reprod. 28(8):2265-75.