The first study to investigate the relationship between eating fruit and vegetables containing pesticide residues and the quality of men's semen has shown a link with lower sperm counts and percentages of normally-formed sperm. The study, which is published online today (Tuesday) in Human Reproduction shows that men who ate the highest amount of fruit and vegetables with high levels of pesticide residue had a 49% lower sperm count and a 32% lower percentage of normally-formed sperm than men who consumed the least amount. An accompanying editorial says the findings have important implications for human health.

However, the study of 155 men showed that, overall, the total amount of fruit and vegetables consumed was unrelated to changes in any measurements of semen quality in the group as a whole.

Assistant Professor of Nutrition and Epidemiology at the Harvard T.H. Chan School of Public Health in Boston (USA), Jorge Chavarro, said: "These findings should not discourage the consumption of fruit and vegetables in general. In fact, we found that total intake of fruit and vegetables was completely unrelated to semen quality. This suggests that implementing strategies specifically targeted at avoiding pesticide residues, such as consuming organically-grown produce or avoiding produce known to have large amounts of residues, may be the way to go."

Previous studies have shown that occupational exposure to pesticides might have an effect on semen quality, but so far there has been little investigation of the effects of pesticides in diet.

Prof Chavarro, his student Dr Yu-Han Chiu and colleagues analysed 338 semen samples from 155 men attending a fertility centre between 2007-2012 as part of the ongoing, prospective "Environment and Reproductive Health" (EARTH) Study. The men were eligible for the study if they were aged 18-55, had not had a vasectomy, and were part of a couple planning to use their own eggs and sperm for fertility treatment.