How sperm transmit dad’s weight to his kids

"The way we eat and our level of physical activity before we conceive may be important to our future children's health and development," says Soetkin Versteyhe. (Credit: iStockphoto)

A study comparing sperm cells from 13 lean and 10 obese men reveals different epigenetic marks that could alter the next generation’s appetite.

The researchers also followed six men before and one year after gastric-bypass surgery to find out how it affected the epigenetic information contained in their sperm cells. The researchers observed an average of 4,000 structural changes to sperm cell DNA from the time before the surgery, directly after, and one year later.

“This is early evidence that sperm carries information about a man’s weight.”

“Today, we know that children born to obese fathers are predisposed to developing obesity later in life, regardless of their mother’s weight,” says Ida Donkin, a lead author of the paper. “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.”

The paper is available early online in the journal Cell Metabolism.

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“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 behavior or their future children,” says Romain Barrès, an associate professor at the University of Copenhagen.

“Epidemiological observations revealed that acute nutritional stress—e.g., famine—in one generation can increase the risk of developing diabetes in the following generations,” says Barrès. He also references a study showing that the availability of food in a small Swedish village during a time of famine correlated with the risk of their grandchildren developing cardiometabolic diseases.

The grandchildren’s health was likely influenced by their ancestors’ gametes (sperm or egg), which carried specific epigenetic marks—for example, chemical additions to the protein that encloses the DNA, methyl groups that change the structure of the DNA once it is attached, or molecules also known as small RNAs.

Epigenetic marks can control the expression of genes, which has also been shown to affect the health of offspring in insects and rodents.

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“In our study, we have identified the molecular carrier in human gametes that may be responsible for this effect,” says Barrès.

By detecting differences in small RNA expressions (where the function is not yet determined) and DNA methylation patterns, the researchers have proven that weight loss can change the epigenetic information men carry in their spermatozoa. In other words, what is transmitted in the father’s sperm can potentially affect the development of a future embryo and, ultimately, it can shape the child’s physiology.

“We did not expect to see such important changes in epigenetic information due to environmental pressure,” says Barrès. “Discovering that lifestyle and environmental factors, such as a person’s nutritional state, can shape the information in our gametes and thereby modify the eating behavior of the next generation is, to my mind, an important find,” he adds.

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Considered in the context of obesity, the discovery that weight loss in fathers-to-be potentially affects the eating behavior of their offspring is groundbreaking.

“The study raises awareness about the importance of lifestyle factors, particularly our diet, prior to conception. The way we eat and our level of physical activity before we conceive may be important to our future children’s health and development,” says Soetkin Versteyhe, co-first author of the paper.

This field of research is in its early days, but the study disrupts the current assumption that the only thing our gametes carry is genetic information, and there is nothing we can do about it. Traits that we once thought were inevitable could prove modifiable, and what we do in life may have implications not only for our own health but also the health of our children and even our grandchildren.

Source: University of Copenhagen