Men, if you want to make sure you have grandkids, you might want to take a look at how much protein is in your diet. Researchers at Monash University in Malaysia found that how a man eats can affect his son’s ability to reproduce.

The study looked at the diets of fruit flies to see if the dad’s nutritional background impacted his son’s sperm. Turns out, fathers who ate more protein had offspring that were better able to compete against another male’s sperm within the female reproductive tract.

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“Our study found that males that were raised on either high or low protein diets, but spent their adulthood on an intermediate diet, produced sons that had large differences in gene expression, which most likely contributed to the resulting differences in sperm competitiveness,” says lead researcher Dr. Zajitschek in a statement.

Aside from having a better chance at impregnating females, the fruit flies with carnivorous fathers benefited from other changes too.

“We also found that the immune response genes were less active in sons of low-protein fathers, while metabolic and reproductive processes were increased in sons of fathers on a high protein diet,” Zajitschek says.

Of course, the test does not prove that eating a high protein diet will help carry on the family name, since it was carried out on insects. But the fruit flies were chosen because they have similar pathways and characteristics with human genes, indicating this might be true for us too.

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If dad wasn’t a big fan of steak, that doesn’t mean you’re out of luck. As Men’s Health reports, there are other ways to ensure your sperm is healthy, including working out regularly. Consuming lycopene-rich foods can help with defects. The magazine claims that decreasing cell phone use can increase mobility and a lycopene-rich diet can keep the little swimmers healthy.

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