According to a recent study in the journal Cell Metabolism, a man’s weight may influence the genetic information that is codified and transmitted to offspring through his sperm. The study, entitled “Obesity and Bariatric Surgery Drive Epigenetic Variation of Spermatozoa in Humans,” revealed that the sperm cells of lean and obese men present different epigenetic traits in the genes that are associated with appetite control, and that such traits are part of the sperm’s genetic information. The findings suggest a biological explanation to a child’s predisposition to obesity.
Dr. Romain Barrès, the study’s senior author, said that this “research could lead to changing behavior, particularly pre-conception behavior of the father. It’s common knowledge that when a woman is pregnant she should take care of herself — not drink alcohol, stay away from pollutants, etc. — but if the implication of our study holds true, then recommendations should be directed towards men, too.”
The first phase of the study, conducted by the University of Copenhagen, compared the DNA of 13 lean men and 10 obese men. The epigenetic patterns of the ejaculate were analyzed as well as the expression of the circulating small RNAs, small RNA molecules which do not codify any particular information but regulate protein expression. Epigenetic marks can control how genes are expressed, and this has also been shown in insects and rodents to affect the health of offspring.
By comparing these two, Dr. Barrès and the team verified that although the epigenetic marks did not differ between obese and lean men, variations were seen in small RNAs and in the methylation of genes associated with brain development and appetite.
Wondering if these differences were byproducts of obesity or lifestyle, the researchers then conducted a second phase to track six obese men undergoing weight loss surgery and determine its affect on their sperm. They observed an average of 5,000 structural changes in sperm DNA from the time before surgery, immediately after, and one year later, and recommend further studies to determine what these structural changes might mean.
Dr. Barrès and his lab are now collaborating with a fertility clinic to study epigenetic differences in discarded embryos from the sperm of men with differing body weights. “It is clear that these epigenetic changes happen in mice and rats,” Dr. Barrès said in a press release, “but we also need to know if this also happens in humans and whether this is a significant driver for changing our traits.”