Between 60-80% of dietary estrogens come from dairy products in the Western world. Estrogens are most commonly considered the “female” hormone, but estrogens are important in lower amounts in men. However, too much estrogen in a man (such as in obesity) can have negative effects on men’s health including male fertility. A recent study from May 2013 from Harvard researchers studied 189 healthy and active men (between ages 18 and 22) to check if dairy milk products (with estrogens) had a relationship with semen quality. The study identified that increased full fat dairy food intake was associated with slower moving sperm and more abnormal sperm shapes (morphology). Additional studies are needed to study this possible effect; if validated, it would indicate that men trying to have children should limit their intake of high fat milk products.