COPENHAGEN, Denmark, Dec. 4 (UPI) -- Men's weight affects markers on sperm cells that can affect the eating behavior and health of their children, researchers in Denmark found in a small study.
While obese parents are already known to increase the risk for children to become obese, previous studies have also shown a father's obesity affects the way genes are expressed in sperm.
The new study, however, focused on the differences in normal weight and obese men's sperm. Large differences were seen, and when men in the study underwent gastric bypass surgery, markers in their sperm changed over time as their diet and lifestyle improved after surgery.
Researchers at the University of Denmark said their work shows the expression of genetic data can be changed with lifestyle alterations, which they think could lead to methods of preventing the transmission of obesity or other disorders from parents to children.
"Today, we know that children born to obese fathers are predisposed to developing obesity later in life, regardless of their mother's weight," said Dr. Ida Donkin, a researcher at the University of Copenhagen, in a press release. "It's another critical piece of information that informs us about the very real need to look at the pre-conception health of fathers. And it's a message we need to disseminate in society."
In the first part of the study, researchers compared sperm cells from 13 thin men with a mean BMI of 22.9 and 10 obese men with a mean BMI of 31.8, finding the way the sperm acted and looked on sight were different, before noting differences in their expression of genes -- of which there were hundreds.
The second part of the study had researchers following six men before and up to a year after gastric bypass surgery. Within weeks after surgery, the researchers found 3,000 differences in epigenetic patterns of the men's sperm. A year after surgery, researchers said there were upwards of 5,000 changes.
While they are unsure exactly how it works, researchers said the knowledge that we inherit some of our lifestyle from parents was reinforced, however the new research shows parents can change what their children may inherit by changing their own lifestyles.
"We certainly need to further examine the meaning of these differences; yet, this is early evidence that sperm carries information about a man's weight. And our results imply that weight loss in fathers may influence the eating behaviour or their future children," says Romain Barrès from the Novo Nordisk Foundation Center for Basic Metabolic Research.
The study is published in Cell Metabolism.