Diet change by would-be dads can cut obesity risk in their kids, says controversial study

Millions of children across the world are growing up with a weight problem. Latest figures show that in 2022/23 more than one in five pupils leaving primary school in the UK were classed as obese.

According to the World Heath Organisation the issue is not just in the UK with the number of obese five to 19-year-olds standing at 160 million in 2022. Now researchers have discovered a potential tool to help fight the problem - although the findings have proved controversial.

Scientists have examined the diet of would-be mice dads to see if they could make a difference. The team from Syracuse University found those on a diet high in fish oil made a difference to their children.

The researchers fed male mice a high-fat diet with or without added fish oil. They discovered the offspring of the males which were fed the fish oil had a lower body weight and better metabolic health than those of fathers without the supplement.

Latha Ramalingam, PhD, assistant professor in nutrition at Syracuse University said: "While further human studies are needed, this discovery opens a new frontier in our understanding of how parents, beyond just genetics, influence their offspring's well-being. Fish oil, a readily available and safe supplement, could become a powerful weapon in our fight for a healthier next generation."

The team believe this is the first study which has looked at inheritance patterns exclusively in the paternal line. Its previous work has examined the benefits of fish oil supplements in mothers for reducing childhood obesity risk.

In the new study almost 150 male mice were given a high-fat diet either with or without added fish oil. They then mated with female mice which had consumed a regular healthy low-fat diet.

The team discovered that offspring that were fed a low-fat healthy diet fathered by males receiving fish oil weighed less at seven and 21 days than offspring of the males not receiving fish oil. Female offspring from males receiving fish oil also had improved metabolic health as measured by glucose clearance and insulin sensitivity.

Dr Ramalingam added: "This concept offers a significant potential to reshape our strategies in combating childhood obesity. Picture a future where pre-conception dietary guidance isn't solely directed at mothers, but also involves fathers, enabling them to play a more active role in promoting their children's well-being right from the start."

The team is now looking at the potential mechanisms through which dietary changes affect sperm. They hope to be able to understand how this information transfer influences the subsequent generation.

The findings were being presented by Sarah Dellet, a graduate student in Ramalingam’s lab, at NUTRITION 2024.  Yet they have been criticised by King’s College London.

Dr Katie Dalrymple, lecturer in nutritional sciences at King’s College London, said: “This study in mice highlights the link between paternal fish-oil intake and offspring health, but it cannot be assumed that the same is true in humans. We don’t have enough information from this study to suggest that men thinking of starting a family should take fish oils to improve the health of their daughters.

“I would advise anyone considering starting a family to eat a varied and balanced diet, with a focus on fruits and vegetables, wholegrains, nuts and lean protein sources and to also cut down on alcohol intake and smoking.” Prof Keith Frayn, emeritus professor of human metabolism at Oxford University, said: “It is clear that the dose of fish oil given to the mice was far higher than a human would take even if a high-strength pharmaceutical version were used.

“We are far from ready to extrapolate this to advice to prospective fathers.”