On the other hand, researchers from the Harvard University School of Public Health, led by Myriam Afeiche, have shown that whole dairy products negatively affect the quality of semen . The study included data from only 189 men between the ages of 19 and 25, but reveals that men who consume 3 servings of whole dairy products – for example, 3 glasses of milk – have semen of 25% lower quality than men. they keep those products out of their diet. This could be attributed to the fact that estrogen, the female hormone par excellence, is present in cow's milk, according to the main author of the work.