It’s well-known that the offspring of obese parents tend to become obese themselves. Both environmental and genetic factors govern this association. Recently, a pair of studies has shed considerable light on those genetic factors, and in particular the role that a father’s diet has on his kids.
In the first study, Sheau-Fang Ng and colleagues at the University of New South Wales randomized a cohort of male rats to receive either a high-calorie diet or a healthy diet, and then had them mate with normal, healthy female rats.
The scientists found that as the daughters of the obese dads grew to become adults, they exhibited impaired glucose tolerance and elevated insulin levels that were not seen in the daughters of normal-weight dads. This turned out to be true even though both sets of offspring had similar amounts of fat and muscle mass, and similar blood triglyceride and leptin levels.
The scientists performed genetic studies on the 2 groups to better understand the cause of these differences. These studies revealed that 642 genes were expressed differently in the 2 groups, and all of them were involved with glucose metabolism and insulin production. The anatomic site where the changes had their impact was localized to pancreatic B-cells which are known to produce insulin.
In their write-up, Sheau-Fang’s group claimed that theirs was “the first direct demonstration in any species that a paternal environmental exposure can induce intergenerational transmission of impaired glucose-insulin homeostasis in their female offspring.”
In the second study, Benjamin Carone, Oliver Rando and colleagues at the University of Massachusetts randomized male mice to receive a normal diet or a low-protein diet. As with the first study, the males were then invited to mate with females that had been fed a normal diet. The scientists found that the progeny of protein-deprived dads had several hundred genetic modifications that weren’t present in those fathered by the dads that had received the normal diet.
In this case, the modified genes governed fat and cholesterol synthesis. “It’s consistent with the idea that when parents go hungry, it’s best for offspring to hoard calories,” Rando said in a press release organized by Cell, the scientific journal in which the second study was published.
Although these studies featured rats and mice, similar epigenetic phenomena probably occur in humans as well. For example, a study by Swedish scientists has shown that the grandchildren of men who were adolescents during periods of widespread famine had a much higher prevalence of diabetes and weight problems.