13 June 2012
Sperm quality unaffected by lifestyle choices
by Will Parker
Medical advice given to sub-fertile men about smoking, alcohol, drugs and obesity is of little value, say UK medicos who contend that many so-called lifestyle "risks" appear to have little or no effect on sperm health. The researchers behind the new findings, from the Universities of Manchester and Sheffield, say that infertility/lifestyle advice should accordingly be radically overhauled.
The study, published in Human Reproduction, recruited more than 2,000 men from fertility clinics around the UK and asked them to fill out detailed questionnaires about their lifestyle. The information was then compared between the men who ejaculated low numbers of swimming sperm and the remaining group of men who produced higher numbers.
The team chose to use the number of swimming sperm men ejaculated to assess fertility as this broadly correlates with how fertile a man is likely to be and also often determines the type of fertility treatment that may be used if required.
The researchers found that men who ejaculated low numbers of swimming sperm were 2.5 times more likely to have had testicular surgery, twice as likely to be of black ethnicity, and 1.3 times more likely to be in manual work, not wear boxer shorts, or not had a previous conception. Surprisingly, men's use of recreational drugs, tobacco, alcohol, as well as their BMI, had little effect.
"Our results suggest that many lifestyle choices probably have little influence on how many swimming sperm they ejaculate. For example, whether the man was a current smoker or not was of little importance. The proportion of men who had low numbers of swimming sperm was similar whether they had never been a smoker or a smoker who was currently smoking more than 20 cigarettes a day. Similarly, there was little evidence of any risk associated with alcohol consumption," said researcher Andrew Povey, from the University of Manchester.
The findings potentially overturn much of the current advice given to men about how they might improve their fertility. "Delaying fertility treatment then for these couples so that they can make changes to their lifestyles, for which there is little evidence of effectiveness, is unlikely to improve their chances of a conception and, indeed, might be prejudicial for couples with little time left to lose," Povey said.
The researchers cautioned that unhealthy choices could still impact other aspects of sperm health that were not included in the study; such as the size and shape (sperm morphology) or the quality of the DNA contained in the sperm head.
Interestingly, the researchers say the less healthy sperm from manual workers was likely due to chemical exposure. "The higher risk we found in manual workers is consistent with earlier findings that chemicals at work could affect sperm and that men should continue to keep work exposures as low as possible," explained researcher Nicola Cherry.
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Source: University of Manchester