MEN who eat a diet rich in fruit, vegetables and fish could boost their chances of becoming a father, according to a new study.
A Mediterranean-style diet, which also contains leafy vegetables, pulses and whole grains, can enhance sperm motility by 11pc.
This could be especially important for couples who are trying to conceive naturally, due to the need for sperm to be 'strong swimmers'.
The research comes as a separate study found that men who take moderate exercise can also positively impact their sperm motility.
Both studies were presented at the American Society for Reproductive Medicine (ASRM) conference in Orlando.
In the first, experts from universities including the Harvard School of Public Health examined the diets of more than 180 men aged 18 to 22.
They split those who ate any Mediterranean-type items into four subsets, from those with the highest intake of these nutrient-rich foods to those with the lowest. Those in the highest group had an increased sperm motility of 11pc compared to the lowest.
Audrey Gaskins, from Harvard's Department of Nutrition, said: "I think motility is most important for couples who are trying to conceive naturally. It's our hope that a small increase could lead to a small increase in fertility rates."
Dr Edward Kim, from the Society for Reproduction and Urology, said: "There is no doubt that motility is one of the most important parameters that we look at in semen quality. These findings are intriguing."
Dr Allan Pacey, senior lecturer from the academic unit of reproductive and developmental medicine at the University of Sheffield, said that the influence of a man's diet on semen quality had been of interest for some time.
He said the latest study "nicely illustrates that a good diet is of benefit when trying to conceive".
In the second study, from Yamaguchi University in Japan, 215 men completed a questionnaire about their exercise habits and gave semen samples.
Men were given a score based on whether they did strenuous, moderate or light exercise. The group reporting moderate exercise had the highest average sperm motility.
Dr Dolores Lamb, president-elect of the ASRM, said: "Exercise is a component of an overall healthy lifestyle, which contributes to reproductive health."