A father's diet before sex can play as important a role as nutrition of the expectant mother in deliveirng a healthy baby, new research suggests.
The findings suggest that men should avoid having a diet high in carbohydrates and low in protein.
"We were really surprised," said Michal Polak, a Professor at University of Cincinnati in the US.
"In many species, the moms do a lot of the care. So we expect there to be an effect from maternal diet on offspring because of that strong link. But it was a real surprise to find a link between paternal diet and offspring," Polak said.
For the study published in the journal Proceedings of the Royal Society B, the researchers manipulated the nutrition of male fruit flies and observed a strong correlation between poor diet and poor survivorship among their offspring.
Scientists regularly study fruit flies because they share 60 per cent of our genes and more than 75 per cent of our disease genes.
Geneticists have mapped their entire genome. More than 150 years of study have made this unassuming little fly a good model system, Polak said.
For the, Polak isolated females and males of the fruit fly species Drosophila melanogaster, which is famous for its enormous red eyes and high reproductive capacity.
A single fly can lay 50 eggs per day or as many as 2,000 eggs in her short two-month lifetime.
The researchers fed females the same diet. But they fed males 30 different diets of yeast and sugars.
The flies could eat all they wanted from the agar mixture in the bottom of their glass beaker homes, but the quality of the food varied dramatically from low to high concentrations of proteins, carbohydrates, and calories..
After 17 days on the strict diet, the males were mated individually and consecutively with two females, which all received the same diet of yeasted cornmeal.
The researchers found that embryos from the second mating were more likely to survive as their fathers' diets improved in nutrition.
These effects were less apparent in the first mating. Likewise, embryo mortality was highest for offspring of males that fed on a high-carbohydrate, low-protein diet.
The study also found a slightly higher incidence of embryo mortality associated with male flies in the first mating that were fed the highest-calorie diet.