In the study, men who ate the highest amount of fruit and vegetables with high levels of pesticide residue had a 49 per cent lower sperm count and a 32 per cent lower percentage of normally-formed sperm than men who consumed the least amount.
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.
"In fact, we found that total intake of fruit and vegetables was completely unrelated to semen quality," said Chavarro.
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.
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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.
Researchers divided the men into four groups, ranging from those who ate the greatest amount of fruit and vegetables high in pesticides residues (1.5 servings or more a day) to those who ate the least amount (less than half a serving a day).
The group of men with the highest intake of pesticide-heavy fruit and vegetables had an average total sperm count of 86 million sperm per ejaculate compared to men eating the least who had an average of 171 million sperm per ejaculate - a 49 per cent reduction.
There were no differences seen between men in the four groups who consumed fruit and vegetables with low-to-moderate pesticide residues.
In fact, there was a significant trend towards having a higher percentage of normally shaped sperm among men who consumed the most fruit and vegetables with low pesticide residues - a relative increase of 37 per cent from 5.7 per cent to 7.8 per cent.
The study was published in the journal Human Reproduction.