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 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 per cent lower sperm count and a 32 per cent 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, 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” 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.
The men’s diet was assessed by means of a food frequency questionnaire, and they were asked how often, on average, they had consumed how many portions of fruit and vegetables, using standard portion sizes such as one apple, or half an avocado.
The fruit and vegetables were categorised as being high, moderate or low in pesticide residues based on data from the annual United States Department of Agriculture Pesticide Data Programme. Fruit or vegetables that were low in pesticide residues included peas, beans, grapefruit and onions. Those that had high residues included peppers, spinach, strawberries, apples and pears. These data took account of usual practice in food preparation, such as whether the fruit and vegetables had been peeled and washed.
The 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). They also looked at men who ate fruit and vegetables with low-to-moderate pesticide residues.
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. The percentage of normally formed sperm was an average of 7.5 per cent in men in the group with the lowest intake and 5.1 per cent in the men with the highest intake – a relative decrease of 32 per cent.
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.