Fellas, want a better chance of passing along your genes? Try laying off the fried food. A more healthful diet will not only help you get fitter, but, new research indicates, it might also increase the odds that your sperm are in better shape, too.
A whole host of factors might impair male fertility—including alcohol intake, smoking, drug use, excessive heat, environmental factors and biological abnormalities. Another candidate? Eating too much fat, according to the study, published online March 13 in Human Reproduction.
Researchers recruited men from couples seeking help at a Massachusetts fertility clinic. Ninety-nine men, whose average age was 36, were surveyed about their dietary habits, lifestyle and health history. Combining that information with an analysis of a subset of the men's semen samples and blood, the investigators found that men who consumed more fat had lower sperm counts. For every extra 5 percent of a man's diet that was made up of fat, his sperm count dipped 18 percent. The news was even worse for men with substantial saturated fat intake. With each 5 percent increase in saturated fat as part of the total diet, sperm count dove 38 percent.
But not all fats are created equal. In fact, men who ate more good, omega-3 fatty acids—such as those found in flax seeds or some fish—actually had more healthy-looking sperm. The researchers are still not entirely sure about why these patterns are emerging, but they are already planning additional research.
Not all of the men in the study had low sperm counts or other problems with sperm, such as sluggishness; in fact, 41 percent were perfectly normal on that score. (Roughly a third of infertility issues stem from the man, about a third from the woman, and the rest are either a combination of the two or unknown.) But the findings do suggest that eating too much saturated fat could be part of the problem for some men.
Like much of the U.S. adult population, about 71 percent of the men in the study were overweight or obese. But with extra analysis, "we were able to isolate the independent effects of fat intake from those of obesity," Jill Attaman, of Harvard Medical School and a co-author of the new study, said in a prepared statement. Two thirds of the men had also never smoked, helping to nix that from a reason they might be experiencing fertility challenges.
Diet, in addition to affecting the likelihood of a man's genes being passed to a new generation, might also change how his offspring develop. Previous research in rats has shown that daughters born to male rodents on a high-fat diet had more health problems later. These so-called epigenetic changes inherited from their father made the female offspring more susceptible to diabetes.
"If men make changes to their diets so as to reduce the amount of saturated fat they eat and increase their omega-3 intake, then this may not only improve general health, but could improve their reproductive health, too," Attaman said.
So a diet that is low in saturated fats will likely not only be good for your jeans, but it will likely help your genes as well.