Pesticides and semen quality

Men who ate fruits and vegetables with higher levels of pesticide residues - such as strawberries, spinach, and peppers - had a lower sperm count and a lower percentage of normal sperm than those who ate produce with lower residue levels.

This is according to a new study by Harvard T.H. Chan School of Public Health.

The study found that men who ate the highest amount of fruit and vegetables with high levels of pesticide residue had a 49 percent lower sperm count and a 32 percent lower percentage of normally-formed sperm than men who consumed the least amount.

No reason to skimp on salad

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.

"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," said Assistant Professor of Nutrition and Epidemiology at the Harvard T.H. Chan School of Public Health in Boston (USA), Jorge Chavarro.

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.

Fruit and vegetables low in pesticides

For the study, 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 Program.

Fruit or vegetables that were low in pesticide residues included:

• Peas
• Beans
• Grapefruit

Fruit and vegetables high in pesticides

Those that had high residues included

• Peppers
• Spinach
• Strawberries
• Apples

These data took account of usual practice in food preparation, such as whether the fruit and vegetables had been peeled and washed.

Study of 155 men

Prof Chavarro, his student Dr Yu-Han Chiu and colleagues analysed 338 semen samples from 155 men attending a fertility centre between 2007 and 2012. The men's diet was assessed by means of a food frequency questionnaire.

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 percent reduction.

The authors believe that this is the first report on the consumption of fruits and vegetables with high levels of pesticide residue in relation to semen quality but point out that there are a number of limitations to the study and further research is needed. They also point out that pesticide use varies from country to country.

Source: Oxford University Press (OUP) Sciencedaily Image credit: muammerokumus