Published: Tuesday 31st March 2015 by The News Editor
Pesticide residues coating non-organic fruit and vegetables may be harming men’s fertility, new research suggests.
Scientists demonstrated a link between the chemicals, sprayed on to crops to prevent damage by insect pests, and reduced sperm count and quality.
The study of 155 men found that those who ate the most fruit and vegetables with high pesticide residue levels had a 49% lower sperm count than those who consumed the least. They also had 32% fewer sperm that was normally formed.
While the American nutritionist who led the research suggested switching to organic produce, other scientists said the findings should be treated with caution.
Leading British fertility expert Professor Allan Pacey, from the University of Sheffield, said: “This is a very interesting paper that raises the possibility that pesticide residues in our food may be a contributory factor in male infertility, at least in some men.
“The idea has been raised before, but to my knowledge this is the first paper that has investigated this question in a systematic way. That said, whilst the results are tantalising, they should be interpreted with caution as the study is not without its flaws and limitations.”
The study involved analysing 338 semen samples taken from 155 men attending a US fertility centre between 2007 and 2012 as part of an on-going investigation into environmental effects on reproduction.
Participants were aged between 18 and 55 and all were from couples planning to use their own eggs and sperm for fertility treatment.
Through a food questionnaire, the men were asked to give details about their diets. Fruits and vegetables were categorised as being high, moderate or low in pesticide residues based on data from the US Department of Agriculture.
Among those in the “high” category were apples, pears, peppers, spinach and strawberries. “Low” residue foods included peas, beans, grapefruit and onions.
Men with the highest intake of pesticide-heavy fruit and vegetables – at least 1.5 servings per day – had an average total sperm count of 86 million sperm per sample compared with 171 million for those whose consumption was lowest.
The percentage of normally formed sperm averaged 7.5% in the lowest intake group and 5.1% in the highest.
Low-to-moderate residue levels did not appear to affect semen quality, according to the results published in the journal Human Reproduction. In fact, consumption of fruit and vegetables with low pesticide levels was significantly associated with having more sperm that was normally formed.
Study leader Dr Jorge Chavarro, assistant professor of nutrition and epidemiology at the Harvard T.H. Chan School of Public Health in Boston, 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.”
The authors acknowledged limitations to the study, including the fact that men attending fertility clinics may not be representative of the population as a whole.
Almost half the men taking part in the research had at least one semen characteristic below the reference limits set by the World Health Organisation.
In addition, diet was assessed only once and could have changed over time, and no data was available on whether the food was grown conventionally or organically.
The researchers did take into account food preparation practices, such as whether fruits and vegetables had been peeled and washed.
In an accompanying editorial, Dr Hagai Levine, and Professor Shanna Swan, both from the Icahn School of Medicine at Mount Sinai, New York, wrote: “Despite the relatively small sample size and exposure assessment limitations, the paper makes a convincing case that dietary exposure to pesticides can adversely impact semen quality. While this finding will need to be replicated in other settings and populations, it carries important health implications.”
Prof Pacey pointed out that the scientists did not measure the pesticide residues in the actual food the men ate but inferred the levels from other data.
It was also possible that some other aspect of diet or lifestyle might have been affecting men’s sperm quality.
“I think it would be important that the newspaper headlines that accompany this article don’t discourage men from eating their quota of fresh fruit and vegetables each day as this is important for other health reasons,” said Prof Pacey. “There is also no evidence at present that switching to organic fruit and vegetables will improve semen quality, although it will obviously do no harm. But I hope that this paper will encourage other studies to take place in this area, so that we might be able to answer the question once and for all.”
Dr Jackson Kirkman-Brown, from Birmingham Women’s Fertility Centre, said: “The paper highlights a growing body of evidence that diet can affect male fertility and sperm quality.
“The data do not really allow us to assess whether it is actual pesticide residue or simply choice of vegetable type which may be affecting the sperm parameters – pesticide itself was not measured and indeed some patients could have been eating organic fruit and vegetables – as it was published general average levels that were used to assess how much individuals may have consumed. Therefore this paper may cause unnecessary worry.
“Men wishing to optimise their sperm quality should still eat a healthy balanced diet until more data is available.”
Published: Tuesday 31st March 2015 by The News Editor