Moderate alcohol consumption and disorders of human spermatogenesis

Environmental factors are suspected to be responsible in part for the deterioration in semen quality observed worldwide during the recent few decades. Alcohol might be one factor, considering the frequent changes in testicular function associated with heavy drinking. The dose-dependent effects of alcohol on human spermatogenesis are, however, not well known. We analyzed spermatogenesis and testicular tissue morphology of 195 men, aged 35-69 years, with computer-assisted microscopy in this autopsy study. The men were categorized into controls and four "consumption groups" according to the average daily alcohol consumption, which was determined on the basis of blind interviews with relatives and acquaintances. When the average daily alcohol consumption was 40 g or less, 59 (66%) of the 90 men showed normal spermatogenesis, whereas 31 (34%) had partial spermatogenic arrest (SA). Of the 31 men with average daily intake between 40 and 80 g, 17 (54%) showed normal spermatogenesis, 13 (42%) had partial or complete SA, and 1 man exhibited more severe testicular damage-"Sertoli cell only" (SCO) syndrome. Among men with daily intake between 80 and 160 g, only 13 of 35 men showed normal spermatogenesis (37%), 19 (54%) had partial or complete SA (odds ratio = 2.92), and 3 (9%) had the SCO syndrome (odds ratio = 16.85). The frequencies of spermatogenic disorders were similar in men drinking in excess of 160 g. Both SA and the SCO syndrome showed a clear dependence on daily dose; p < 0.0001 and p < 0.0004, respectively. We conclude that long-term average daily consumption of < 40 g of alcohol seems not to be associated with disorders of spermatogenesis. Consumption of moderate amounts of alcohol may affect semen quality more often than previously thought, whereas high alcohol consumption may even be associated with serious disorders of spermatogenesis.