Carrots can not only help men see in the dark – they can also improve the health of their sperm.
Researchers investigating the effect of fruit and vegetables on the health of sperm discovered that carrots produced the best all-round results.
They had the greatest effect on 'motility' – a term used to describe the ability of sperm to swim towards an egg.
Researchers at Harvard University in the U.S. asked almost 200 young men to follow diets containing a variety of fruit and veg before testing to see what effect it had on sperm. Yellow and orange foods were found to help make the sperm stronger.
The boost was attributed to pigments called carotenoids because the body converts some of these into health-boosting antioxidants.
Sweet potato and melon can enhance the quantity and quality of sperm, but carrots were found to improve sperm performance by between six and a half and eight per cent, according to a report in the journal Fertility and Sterility.
The report said: "In a population of healthy young men, carotenoid intake was associated with higher sperm motility and, in the case of lycopene, better sperm morphology.
"Our data suggest that dietary carotenoids may have a positive impact on semen quality."