Effects of Alcohol Use on Sperm Chromatin Structure

The evaluation of the infertile couple is often complex as multiple factors in both the male and female can contribute, including social history. Previous studies have displayed that male ethanol consumption can disturb sperm motility, nuclear maturity, and DNA integrity, likely resulting in infertility. A previous study primarily looking at vitamin D levels and sperm parameters incidentally demonstrated increased high DNA stainability (HDS), which correlates with immaturity of the sperm nucleus, in males who do not use alcohol. The main purpose of this study is to evaluate the effects of male alcohol use on sperm chromatin structure analysis (SCSA), including DNA fragmentation and HDS.

This study was a retrospective chart review of 210 consecutive couples that presented to a midsize infertility clinic in the Midwest and had a semen analysis and SCSA performed. Data were extracted from the electronic medical record, de-identified, and independently entered into an Excel spreadsheet by two investigators. The spreadsheets were electronically compared, and discrepancies resolved by reference to the EMR primary data. Data extracted included demographics, tobacco use, alcohol use, occupational exposures, semen analysis results, and SCSA results (DNA fragmentation index (DFI) and HDS. Statistical analysis (regression) was performed on this data set to determine significance with a p-level of 0.05, with primary input being level of alcohol use and outcome being the SCSA parameters.

11% of the cohort had heavy alcohol use (greater tyhan 10 drinks/week), 27% moderate (3-10/week), 34% rare (0.5-3/ week), and 28% no alcohol use. 36% of the cohort had HDS greater than 10% (a marker of immaturity of sperm chromatin). Level of alcohol use was not significantly associated with HDS greater than 10% (p=0.55). Average total DFI was 12.99% (greater than 25% is associated with poorer fertility). Total DFI was not significantly associated with the level of alcohol use (p=0.7). Heavy alcohol use was significantly associated with lower sperm density (p=0.042). Increasing age was significantly associated with increasing DFI (p=0.006), increased sperm density (p=0.002) and lower semen volume (p=0.022). Exposure to heat at work was significantly associated with lower semen volume (p=0.042). Tobacco use was associated with lower sperm motility and lower sperm density (p=0.002).

There was not a significant association between the level of alcohol use (heavy, moderate, rare, or none) and the HDS or DFI of sperm. The overall literature remains equivocal with respect to alcohol's effect on sperm chromatin structure. Heavy alcohol use was associated with lower sperm motility. Alcohol may exert a negative effect on semen parameters via disruption of the testosterone hormonal axis, through direct toxicity to Leydig and/or Sertoli cells, and/or through oxidative damage to sperm DNA. The overall effect on fertility and the possibility of transgenerational effects through DNA damage both require further characterization. Increasing age was associated with poorer sperm parameters as expected. Heat exposure was associated with lower semen volume and tobacco use was associated with lower sperm motility and density.