Turns out sperm quality may be all in the nuts. Specifically, walnuts.
According to a new study by researchers at UCLA and co-funded by the California Walnut Commission, walnuts may improve men's sperm quality.
The study's scientists had 58 healthy men between the ages of 21 to 35 eat half a daily dose of walnuts, and had another group of 59 men avoid snacking on the tree nuts.
They checked both groups' sperm quality 12 weeks later, and found that those men who ate walnuts had improved sperm shape, movement, and vitality, and less chromosomal abnormalities than before they participated in the study, according to CBS News.
"It would be relatively easy to poke fun at studies like this, but there is increasing evidence to show that aspects of a man's diet can affect the number and quality of sperm produced by his testicles," Dr Allan Pacey, senior lecturer in andrology at the University of Sheffield, told BBC News.
Walnuts are the only nuts with significant omega-3 fatty acid levels, which some studies have connected to lowering male infertility, researcher Wendie Robbins of the UCLA Fielding School of Public Health told WebMD.
Around 70 million couples worldwide deal with subfertility or infertility, according to the research, and men are responsible for the difficulty conceiving in 30 to 50 percent of those cases, CBS News reported.