TUESDAY, June 12 (HealthDay News) -- When a man drinks to excess, smokes or otherwise behaves unhealthily, it probably won't damage his sperm, a new British study contends.
But, fertility experts who reviewed the new report, published June 12 in Human Reproduction, weren't in full agreement with the findings.
"I am concerned that this limited and isolated study will convey the wrong message to couples desiring to become parents," said Dr. Natan Bar-Chama, director of the Center of Male Reproductive Health at Mt. Sinai Hospital in New York City.
The study included more than 2,200 men from 14 fertility clinics around the United Kingdom who completed detailed questionnaires about their lifestyle habits. The researchers compared this information to the levels of swimming sperm ejaculated by the men.
Some factors did impact sperm health. For example, men who had low levels of swimming sperm were 2.5 times more likely to have had prior testicular surgery, twice as likely to be black, and 30 percent more likely to have manual labor jobs, not wear boxer shorts (vs. briefs or no underwear), or not to have previously conceived a child.
On the other hand, the researchers also found that men's weight and their use of tobacco, alcohol and recreational drugs had little effect on levels of swimming sperm.
"Despite lifestyle choices being important for other aspects of our health, our results suggest that many lifestyle choices probably have little influence on how many swimming sperm [men] ejaculate," Dr. Andrew Povey, from the University of Manchester's School of Community Based Medicine, said in a university news release.
The findings suggest that lifestyle advice given to infertile men needs to be changed, the researchers added.
They noted that current U.K. guidelines instruct doctors to warn infertile men about the dangers of smoking, drinking, drug use, being overweight and wearing tight underwear. But, this study found that many common lifestyle factors make little difference to male fertility, based on how many swimming sperm men produce.
"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," the researchers wrote.
Povey said the findings potentially overturn "much of the current advice given to men about how they might improve their fertility and suggests that many common lifestyle risks may not be as important as we previously thought. 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."
Experts in the United States weren't entirely convinced.
For his part, Bar-Chama, who is also associate professor of urology and obstetrics, gynecology and reproductive science at Mt. Sinai School of Medicine, said that "a single study that is counter to prior literature and common sense needs to be put into proper perspective."
According to Bar-Chama, "there is a plethora of science publications clearly indicating that illicit drug use such as marijuana, as well as chronic cigarette smoking, impairs semen parameters and fertility. Exposure to increased scrotal temperature as well as an increased BMI [overweight/obesity] is also well known to impair male fertility."
Dr. Avner Hershlag is chief of The Center for Human Reproduction at North Shore University Hospital in Manhasset, N.Y. He said that while "this important study puts to rest many concerns regarding the effect of lifestyle on sperm quality," it doesn't give would-be fathers a free pass to smoke or indulge in
"The study did not find that cigarette smoking was a culprit, yet did not examine the effect of passive smoking on the female partner's fertility," Hershlag noted. And, he said, "while it is reassuring to know that sperm is resilient, I still recommend a healthy lifestyle to improve your chances to conceive."
He also noted that, as regards the finding on race, "this study was done in the UK, and therefore may not apply to African-American men."
The American Urological Association has more about male infertility.