There is growing evidence that, long before you were even conceived, your parents’ lifestyle and environment may be having a profound influence on your health. A new study shows how this can happen.
Researchers at the Novo Nordisk Foundation Center for Basic Metabolic Research compared sperm cells from 13 lean men and 10 obese men and discovered that the sperm cells in each group contains different epigenetic marks that could alter the next generation’s appetite.
Another major discovery was made in a study that followed six men before and one year after gastric-bypass surgery (an effective intervention to lose weight) to find out how the surgery affected the epigenetic information contained in their sperm cells. The findings showed an average of 4,000 structural changes to sperm cell DNA from the time before the surgery, directly after, and one year later.
“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,” said researcher Dr. Romain Barrès.
“Epidemiological observations revealed that acute nutritional stress, e.g. famine, in one generation can increase the risk of developing diabetes in the following generations,” adds Barrès.
He also mentioned a study that showed how the availability of food in a small Swedish village during a time of famine correlated with the risk of their grandchildren developing cardiometabolic diseases.
In this situation, the grandchildren’s health was likely influenced by their ancestors’ gametes (sperm or egg), which carried specific epigenetic marks. These epigenetic marks could be in the form of 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 animal studies.
“In our study, we have identified the molecular carrier in human gametes that may be responsible for this effect,” said Barrès.
By detecting differences in small RNA expressions (where the function is not yet determined) and DNA methylation patterns, the researchers have shown that weight loss can change the epigenetic information men carry in their sperm. 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,” said 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 behaviour of the next generation is, to my mind, an important find,” he adds.
The discovery that weight loss in fathers-to-be potentially affects the eating behavior of their offspring is ground-breaking.
“Today, we know that children born to obese fathers are predisposed to developing obesity later in life, regardless of their mother’s weight. It’s another critical piece of information that informs us about the very real need to look at the pre-conception health of fathers” said Ida Donkin, M.D., one of the lead authors of the paper. “And it’s a message we need to disseminate in society.”
Although this field of research is still in the early days, the new findings run counter to the current assumption that the only thing our gametes carry is genetic information, and there is nothing we can do about it.
Traits we once thought were inevitable could prove modifiable, and what we do in life may have consequences not only for our own health but also for the health of our children and even our grandchildren.
“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,” said Soetkin Versteyhe, co-first author of the paper.
The findings are published in the medical journal Cell Metabolism.