Women are often told that what they eat, how much they drink and the choices they make can have a big impact on their children’s health and development, even long before they get pregnant. But increasingly, animal and human research is suggesting that a man’s lifestyle (and not just his age) can play a big role in the health of future offspring as well.
Epigenetics—the science of how genes are modified by environment and lifestyle, and how those modifications can be passed to new generations—seem to be responsible for many of these effects, says Joanna Kitlinska, assistant professor of biochemistry and molecular and cellular biology at Georgetown University.
“We are learning that it’s very important for both parents to take good care of themselves before conception,” Kitlinska says. For men specifically, here are a few factors to keep in mind.
Vitamin D levels
Preliminary research presented at the European Congress on Obesity in Portugal found that low vitamin D levels in soon-to-be fathers was associated with low height and weight in their children at age 5. The effect may be temporary—the association was no longer significant when kids were checked again at age 9—but the authors still say the finding justifies more research.
“Father’s nutrition status may somehow influence the health, quality and function of germ cells, which are involved in reproduction,” the researchers from University College Dublin concluded in their presentation. Interestingly, no similar association was found between mothers’ vitamin D levels during pregnancy and kids’ height and weight.
It’s well known that children can develop fetal alcohol syndrome (FASD) if a woman drinks while she’s pregnant. But up to 75% of children with FASD have biological fathers who are alcoholics, according to a 2016 review published in the American Journal of Stem Cells, suggesting that paternal alcohol consumption may also be responsible for the condition.
How much a man drinks may affect his future children’s risk of birth defects, says Kitlinska, who co-authored the review.
Animal research has also suggested that male mice who consume high levels of alcohol may be more likely to have children with low birth weights, impaired cognitive function and a greater susceptibility to alcohol’s effects themselves, even if they’ve sobered up before breeding.
Poor diet and obesity
Men who grow up on restricted, low-calorie diets may pass on some advantages to future generations. In studies on Swedish populations, children and grandchildren of men who had a limited food supply during adolescence (because of poverty and crop failure) were less likely to die from cardiovascular disease and diabetes.
Conversely, research also shows that obese fathers are more likely to pass on genes that can raise the risk of obesity, diabetes and brain cancer than men who are normal weight. “How we eat and how much we eat can affect how genes are expressed in our offspring,” says Kitlinska. “It’s kind of nature’s way of preparing children for the environment in which they will be living.”
There’s not a lot of research in humans on paternal stress levels and children’s health, but Kitlinska plans to soon investigate the connection in animals. Previous studies have shown that male mice exposed to stressful environments are subsequently more likely to have offspring with high blood sugar and unhealthy responses to stress themselves.
Smoking and metal fumes
Giving up cigarettes once there’s a new baby in the house is important, but quitting long before that is an even better move. In a 2016 study in the International Journal of Epidemiology, children of men who smoked before their partners got pregnant were three times as likely to have asthma than those whose fathers never smoked.
Dads who smoked before age 15 and those who smoked for the greatest number of years were the most strongly associated with asthma among kids. (No increased risk was seen for children whose mothers smoked prior to conception but not during pregnancy.) Men who were exposed to welding and metal fumes before conception also seemed to pass on an increased risk.