Decreased sperm counts in Swedish users of oral tobacco.
Level 4 - case-series / case-control
Cross-sectional observational study
PubMed 35642735 · doi:10.1111/andr.13198
What was done
Men (n = 613) recruited from the general Swedish population between 2000 and 2010 completed questionnaires regarding smoking and oral moist snuff (snus) use, underwent physical examinations, and provided urine, blood, and semen samples. Semen parameters (sperm concentration, total sperm count, volume, morphology, progressive motility, and DNA fragmentation index via Sperm Chromatin Structure Assay), reproductive hormones, and urinary cotinine levels were assessed. General linear models evaluated associations between snuff use and reproductive measures, adjusting for cigarette smoking and ejaculatory abstinence time.
What was found
Among 109 snuff users compared with non-users, total sperm count was 24% lower (P = 0.03) and serum testosterone was 14% higher (P < 0.001) after adjustments. Urinary cotinine levels were positively associated with testosterone and oestradiol (P < 0.001). Weekly snuff consumption (number of boxes per week) was positively associated with both testosterone and follicle-stimulating hormone (FSH) (P < 0.001). Specific numeric values were not reported in the abstract for sperm concentration, motility, morphology, semen volume, or DNA fragmentation.
Why it matters
While combustible cigarette smoking is known to impair semen parameters, this study provides evidence that non-combustible oral tobacco (snus) is independently associated with reduced total sperm counts and altered reproductive hormone levels.
Limits
The study used a cross-sectional observational design, preventing causal inference. Only 109 of the 613 participants were snuff users. Specific numerical results for several measured parameters (such as sperm motility, morphology, and DNA fragmentation) were omitted from the abstract, and residual lifestyle confounding remains possible.
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