A good amount of research has been devoted to the factors that influence a woman’s fertility, which include nutrition, alcohol, smoking, body mass index, and environmental toxins. Less is known about how food and lifestyle choices affect male fertility. But a new study investigates these connections, and finds that the quality of sperm is significantly affected by food, drink, and other lifestyle variables.

Men whose diets were higher in fruit and grains like oats and wheat had more numerous and more motile sperm. On the other hand, men who drank alcohol and those who were overweight had less numerous and less motile sperm.

In the study, the authors followed 250 men who were trying to get their partners pregnant with a procedure called intracytoplasmic sperm injection (ICSI). They quizzed the men about the types of foods they ate and with what frequency, along with other lifestyle factors like smoking and drinking alcohol. They also did tests to determine the concentration and motility of the men’s sperm (how well they “swam”).

There were some significant links between the men’s lifestyles and their sperm quality. Men whose diets were higher in fruit and grains like oats and wheat had more numerous and more motile sperm. On the other hand, men who drank alcohol and those who were overweight had less numerous and less motile sperm. Men who smoked had normal numbers of sperm, but they were less motile than those of nonsmokers.

When the team looked at how likely the couples were to get pregnant, they found that men who drank alcohol and ate more red meat were significantly less likely to impregnate their partners. Men who ate more vegetables were more likely to conceive. This could be due to increased intake of antioxidants, which benefits the sperm in part by repairing broken DNA.

The authors suggest that the study is particularly important given the fact that fertility and semen quality have declined in the past few decades. This change has been thought to be due to lifestyle changes, the rise in overweight and obesity, and exposure to toxins and pollutants. Luckily, many of the variables are within a person’s power to change. Research has uncovered more and more about the effect of chemical additives like BPA on female fertility and the health of the children. Now, at least, some of the factors affecting men’s fertility have been mapped out and future studies will surely reveal others.

The study was carried out by researchers at the Fertility-Assisted Fertilization Centre in São Paulo, Brazil, and published in the November 10, 2011 online edition of the journal Fertility and Sterility.