Drinking a moderate amount of alcohol, equivalent to two pints a week, has been linked to higher sperm quality than lower or higher alcohol intake.
A study of 323 men in Italy, published in the journal Andrology, found that drinking 4-7 units of alcohol per week was associated with greater semen volume and total sperm count, compared with those who drank 1-3 units or more than 8 units a week.
'Moderate alcohol intake appears positively associated to semen quality in men. They are counselled to limit but not avoid alcohol,' said study author Dr Elena Ricci of the Ca' Granda Ospedale Maggiore Policlinico in Milan, Italy.
The men in the study had a mean age of 39.3 years, and were seeking assisted reproduction after experiencing subfertility with their partner. In a questionnaire on their lifestyle factors, 10 percent of the men said they abstained from alcohol entirely, 30 percent said they drank 1-3 units a week, 30 percent said 4-7 units a week and 30 percent said more than 8 units a week.
After accounting for factors known to affect male fertility – including BMI, smoking, caffeine intake and levels of physical activity – the study found men drinking a moderate amount had the higher measures for two out of four measures of sperm quality (sperm volume and sperm count) compared with men who had lower or higher alcohol intake. However, neither of the other two measures (sperm motility and sperm concentration) were boosted for men drinking in the 4-7 unit a week range.
The findings support earlier research that found moderate alcohol consumption and higher sperm quality are linked. Previous studies, including a 2014 paper, have also underlined that higher alcohol consumption – drinking more than the equivalent of two pints a day – is harmful to male fertility, decreasing sperm quality by a third.
The reasons that moderate alcohol intake appears to be linked to higher sperm quality remain unknown.
'What matters is what is the real effect, and is that constant across the population, or just like other factors that affect people differently, are there individual mechanisms that interplay so that one person may be affected differently to another,' said Professor Simon Fishel, founder and president of CARE Fertility, who was not involved with the research.
The study relied on men reporting how much they drank, which can lead to inaccuracies due to the imperfections of memory, Professor Fishel cautioned. In addition, the study focused on men attending a fertility clinic, so the results may not apply to a healthy population. Men hoping to conceive should think twice before making efforts to tune their alcohol intake to 4-7 units a week, Professor Fishel cautions.
Dr Channa Jayasena, a reproductive endocrinologist at Imperial College London who was also not involved with the study, agreed: 'It is important to highlight that non-drinkers had arguably the best sperm quality of anyone studied. So, I am afraid that aspiring fathers should not be tempted to increase their alcohol intake to improve their fertility.'