Australian researchers have discovered that the sperm of overweight fathers appears to carry a molecular signal that causes their offspring to inherit obesity.
The preliminary study indicates obesity in offspring is more evident and severe in females than in males.
The work by the Robinson Institute Research Centre for Reproductive Health at the University of Adelaide has so far focused on microRNA expression on the sperm of laboratory mice. The next move will be to recruit people into the study of paternal dietary signals carried in sperm and their impact on offspring.
The research was presented at the current World Congress on Human Reproduction in Melbourne.
Researcher Maria Ohlsson Teague said the sperm microRNAs identified are molecular regulators of gene expression in several biological processes, including embryonic development.
The study involved two groups - one of mice fed a high-fat diet, the other fed a good nutritional diet - with screening of the microRNA profile of sperm in both.
"In the group fed the high-fat diet, we discovered that male obesity alters the microRNA profile of sperm, resulting in poor embryo quality as well as obesity in offspring," Dr Ohlsson Teague said.
"This is the first evidence that a father's nutrition can affect the epigenome of his sperm, a non-genetic mechanism to inform the next generation of environmental change.
"We don't yet understand how this occurs and are particularly interested in why it appears to have a greater impact on the female offspring."
Because the transfer of the obesity factor is a biological process, not a genetic one, a father who loses weight and gets fit is less likely to pass on obesity to his children, according to the research.