Investigating the association between alcohol intake and male reproductive function: A current meta-analysis.
Level 3 - non-randomized controlled study
systematic review and meta-analysis of observational studies
PubMed 37159717 · doi:10.1016/j.heliyon.2023.e15723
What was done
A systematic review and meta-analysis evaluated the association between alcohol consumption and male reproductive parameters. Databases were searched for studies comparing non-drinkers, moderate drinkers, and heavy drinkers across measures of semen quality (volume, density, motility, normal/abnormal morphology), seminal antioxidant enzymes, sperm DNA fragmentation, and sex hormones (testosterone, FSH, LH, estradiol, Inhibin B, and SHBG). Data from 40 studies comprising 23,258 men across five continents were synthesized using random-effects models to calculate standardized mean differences (SMD). Publication bias was assessed using Egger's test.
What was found
Alcohol consumption was significantly associated with reduced semen volume (SMD = -0.51; 95% CI -0.77, -0.25) and lower seminal antioxidant enzymes (SMD = -7.93; 95% CI -12.59, -3.28), but showed no overall significant association with sperm density, motility, morphology, or DNA fragmentation. Endocrine findings showed significant decreases in general testosterone (SMD = -1.60; 95% CI -2.05, -1.15), Follicle Stimulating Hormone (SMD = -0.47; 95% CI -0.88, -0.05), and Luteinizing Hormone (SMD = -1.35; 95% CI -1.86, -0.83), with no overall effect on estradiol, Inhibin B, or SHBG. Subgroup analyses showed that the moderate alcoholic group (<7 units/week) had no change in semen indices, whereas heavy alcohol intake (>7 units/week) harmed semen indices and altered sex hormones, notably increasing estradiol.
Why it matters
This review synthesizes global evidence indicating a dose-dependent threshold where heavy drinking (>7 units/week) impairs seminal antioxidant defenses, semen volume, and reproductive hormone regulation, whereas moderate intake shows no measurable change in semen indices.
Limits
The included studies are observational, precluding causal inference and leaving findings vulnerable to residual confounding by lifestyle factors such as smoking, diet, and obesity. Alcohol exposure was assessed via self-report across varied definitions and study populations. The extremely large SMD for antioxidant enzymes suggests substantial heterogeneity in assay methods across studies.
Cited by
- supports A meta-analysis of over 40 studies with more than 23,000 men found alcohol reduced semen volume, semen antioxidant enzymes, testosterone, FSH, and LH, without affecting sperm density, motility, morphology, or DNA fragmentation.