Alcohol is associated with low sperm quality and can have side effects on semen even when drinking only five times a week; this effect is even more pronounced when drinking 25 units of alcohol per week. The idea was presented in a cross-sectional study by Dr. Tina KoldJensen of the University of Southern Denmark and published in BMJOpen on Oct. 2. The study included 1,221 Danish men, aged 18 to 28 years, who completed a form on alcohol consumption and provided a semen sample for military recruitment medical examinations. The subject response rate was 30%. The average amount of alcohol consumed by the subjects in the past week was 11 units (one unit is defined as 12 g of ethanol, which is about the amount in a bottle of beer and a glass of wine.) Sixty-four percent of the subjects had two to three binge drinking episodes in the past 30 days, and 45 percent reported drinking as usual. The researchers found a negative dose-response relationship between alcohol consumption and sperm concentration, total sperm count and proportion of morphologically normal sperm in regular drinkers. This trend was more pronounced in those who drank greater than 25 units of alcohol per week. Men who drank greater than 40 units of alcohol per week had a mean sperm concentration of 3.3?107/mL, while men who drank 1 to 5 units of alcohol per week had a mean sperm concentration of 5?107/mL. This correlation did not hold for those who were not regular drinkers. This did not surprise the researchers because it takes 72 days for sperm to develop and mature. But hormone concentrations can respond quickly, and in fact, recent drinking was associated with multiple binge drinking in the past month and high testosterone concentrations and low sex hormone-binding globulin concentrations. Men who drank more than 30 units of alcohol in the past week were more likely to smoke, consume more caffeine, and were more likely to have sexually transmitted diseases. The researchers did not find a relationship between binge drinking and sperm quality, but noted that subjects who binge drank generally tended to consume more alcohol. “The negative association between alcohol intake and semen quality may be due to the direct side effects of alcohol on spermogenesis or to the different lifestyles, behaviors and diets of heavy drinkers,” the researchers wrote in the article. ”The interpretation of the article’s results is quite subtle,” noted Dr. Jorge Chavarro of Harvard Medical School in an interview with Medscape. dr. Chavarro was not involved in this study, but collaborated frequently with the article’s authors. He concluded that although the trend toward lower sperm concentration was statistically significant, the values at other levels were not significantly different from the reference value of 1 to 5 units. He said, “For me, the only way to tell if the article’s conclusions are correct is to compare these new results with the existing literature.” The existing literature included a meta-analysis that showed no relationship between alcohol intake and semen quality. dr. Chavarro added: “If these results were included in the new meta-analysis, the conclusions might still not be relevant. I think the most innovative aspect of this article is that it reports the effects of binge drinking, something that has not been studied yet.