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Cited by 0Sperm and Testicular FunctionSmoking Behavior and CessationMale Reproductive Health Studies

Impact of Smokeless Tobacco on Semen Quality: A Systematic Review and Meta‐Analysis

Open access
Alqarni, Rayan, Almajed, Ebtesam, Alahmari, Mohammed, Althobait, Nawaf A., Alkathami, Sultan A., AlQurashi, Noura Nawar, Althobaiti, Omar M., Almarzouki, Abdullah +2 more·2026·Andrology
DOI 10.1111/andr.70394
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Abstract

Background: Smokeless tobacco products are widely regarded as a safer alternative to smoking. However, a growing body of evidence points to harmful effects on male reproductive health. The aim of this systematic review and meta‐analysis was to assess the association between smokeless tobacco use and the principal indicators of male infertility. Methods: This review was conducted in accordance with PRISMA 2020 guidelines and registered with PROSPERO (CRD420251056391). A systematic search of PubMed, Medline, Web of Science, and Google Scholar was performed from January 1993 to December 2025. Observational and interventional studies that examined smokeless tobacco exposure in adult men were eligible. Risk of bias was assessed with ROBINS‐I and the certainty of evidence with GRADE. Results: Sixteen studies with a total of 3401 participants met the inclusion criteria. Smokeless tobacco use was associated with lower sperm motility (mean difference, MD: −9.56; 95% confidence interval, CI: −14.85 to −4.28), lower sperm concentration (MD: −14.90; 95% CI: −21.43 to −8.37), lower sperm vitality (MD: −12.86; 95% CI: −19.86 to −5.86), and a higher proportion of abnormally shaped sperm (MD: +3.58; 95% CI: 0.34 to 6.82). Semen pH was slightly but significantly lower in users (MD: −0.03; 95% CI: −0.04 to −0.02). Semen volume was also lower, but the difference did not reach statistical significance (MD: −0.36; 95% CI: −0.76 to 0.04; p = 0.078). Heterogeneity was high for several outcomes ( I 2 > 90%), but sensitivity analyses did not change the direction of effect. The GRADE certainty of evidence was moderate for all pooled outcomes except semen volume, for which it was low. Conclusion: Smokeless tobacco use was associated with poorer semen quality, particularly in sperm motility, concentration, vitality, and morphology. These findings are consistent with smokeless tobacco being an important and frequently overlooked risk factor for male infertility, although the evidence is observational and derived largely from South Asian populations. Clinicians should consider asking about smokeless tobacco use during infertility evaluations, and targeted public health measures appear warranted to address its reproductive effects.

AI snapshot

Written from the paper’s full text.

TL;DR

This systematic review and meta-analysis found that smokeless tobacco use was associated with significantly poorer semen quality, especially lower sperm motility, concentration, and vitality, and more abnormal sperm morphology. The evidence is observational and largely from South Asian populations, so causality and broader generalizability remain uncertain.

Key findings

  • Across 16 cross-sectional studies with 3401 participants (2104 smokeless tobacco users and 1297 controls), users had lower sperm motility (MD: -9.56; 95% CI: -14.85 to -4.28), lower sperm concentration (MD: -14.90; 95% CI: -21.43 to -8.37), and lower sperm vitality (MD: -12.86; 95% CI: -19.86 to -5.86).
  • Users had a higher proportion of abnormally shaped sperm (MD: +3.58; 95% CI: 0.34 to 6.82) and slightly lower semen pH (MD: -0.03; 95% CI: -0.04 to -0.02).
  • Semen volume was lower in users but the difference was not statistically significant (MD: -0.36; 95% CI: -0.76 to 0.04; p = 0.078).
  • Heterogeneity was high for several outcomes (I² > 90%), but sensitivity analyses did not change the direction of effect; GRADE certainty was moderate for all pooled outcomes except semen volume, which was low.

Methods

  • Systematic review and meta-analysis conducted per PRISMA 2020 and registered with PROSPERO (CRD420251056391), searching PubMed, Medline, Web of Science, and Google Scholar from January 1993 to December 2025.
  • Eligible studies examined smokeless tobacco exposure in adult men and reported male reproductive outcomes; 16 cross-sectional studies met inclusion criteria, with risk of bias assessed by ROBINS-I and certainty by GRADE.
  • Continuous outcomes were pooled as mean differences with 95% CIs using inverse-variance random-effects models in Review Manager 5.4.1; morphology was harmonized to percentage of abnormal forms.

Limitations

  • The paper states that all included studies were observational and cross-sectional, so temporality cannot be established; primary studies almost uniformly reported unadjusted comparisons, and meta-regression or subgroup analysis on confounders was not feasible.
  • The paper states that outcome definitions were not fully standardized, morphology thresholds and motility definitions varied, and the evidence base was geographically concentrated: 14 of 16 studies from India or Pakistan and the remaining two from Sudan and Egypt, with no European or North American snus, dip, or nicotine-pouch studies included.
  • The paper states that reproductive hormones and sperm DNA integrity could not be meta-analyzed for lack of poolable data; formal publication-bias tests were not used because each meta-analysis included fewer than 10 studies. The text also makes evident that only cross-sectional studies were ultimately included despite eligibility for randomized and other observational designs.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1111/andr.70394

Cites

28 of 28 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

0 of 39 cited sources checked · 0 supported · 0 flagged

  • Findingown data

    Smokeless tobacco use was associated with a higher proportion of abnormally shaped sperm (MD: +3.58; 95% CI: 0.34 to 6.82).

    “a higher proportion of abnormally shaped sperm (MD: + 3.58; 95% CI: 0.34 to 6.82)”
    • Also stated in: § 3.3.3 Abnormal Morphology · plain
      “users had a significantly higher proportion of abnormal sperm than controls (MD: + 3.58, 95% CI: 0.34 to 6.82; p = 0.031) (Figure 6 ).”
    Quote in the paperSubstantial claim
  • Findingown data

    Semen pH was slightly but significantly lower in smokeless tobacco users (MD: -0.03; 95% CI: -0.04 to -0.02).

    “Semen pH was slightly but significantly lower in users (MD: -0.03; 95% CI: -0.04 to -0.02).”
    • Also stated in: § 3.3.6 Semen pH · plain
      “Users had significantly lower semen pH than controls (MD: -0.03, 95% CI: -0.04 to -0.02; p < 0.001) (Figure 9 ).”
    Quote in the paperNot a substantial claim
  • Findingown data

    Heterogeneity was high for several outcomes (I2 > 90%).

    “Heterogeneity was high for several outcomes ( I 2 > 90%),”
    Quote in the paperNot a substantial claim
  • Findingown data

    Smokeless tobacco use was associated with lower sperm vitality (MD: -12.86; 95% CI: -19.86 to -5.86).

    “lower sperm vitality (MD: -12.86; 95% CI: -19.86 to -5.86)”
    • Also stated in: § 3.3.4 Sperm Vitality · plain
      “Users had significantly lower vitality than controls (MD: -12.86, 95% CI: -19.86 to -5.86; p < 0.001) (Figure 7 ).”
    Quote in the paperSubstantial claim
  • Findingown data

    Smokeless tobacco use was associated with lower sperm motility (MD: -9.56; 95% CI: -14.85 to -4.28).

    “Smokeless tobacco use was associated with lower sperm motility (mean difference, MD: -9.56; 95% confidence interval, CI: -14.85 to -4.28)”
    • Also stated in: § 3.3.1 Sperm Motility · plain
      “Smokeless tobacco users (hereafter 'users') had significantly lower motility than controls (MD: -9.56, 95% CI: -14.85 to -4.28; p < 0.001) (Figure 3 ).”
    Quote in the paperSubstantial claim
  • May combine two claims. 40
  • Classified as probably not a substantial claim. 27
  • The quote only partly states this claim. 3

  • May combine two claims.

    Findingown data

    The included studies almost uniformly reported unadjusted comparisons between users and non-users, and fewer than 10 studies contributed to any pooled outcome.

    “The included studies almost uniformly reported unadjusted comparisons between users and non-users, and fewer than 10 studies contributed to any pooled outcome.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Findingreasoning

    Twelve studies were conducted in India, two in Pakistan, and one each in Sudan and Egypt; 14 of the 16 studies originated from South Asia and two from North-East Africa.

    “Twelve studies were conducted in India, two in Pakistan, and one each in Sudan and Egypt; 14 of the 16 studies therefore originated from South Asia and two from North-East Africa.”
    Quote in the paperNot a substantial claim

  • May combine two claims. The quote only partly states this claim.

    Findingown data

    Sixteen cross-sectional studies with a total of 3401 participants (2104 smokeless tobacco users and 1297 non-user controls) met the inclusion criteria.

    “Sixteen studies with a total of 3401 participants met the inclusion criteria.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Semen volume was lower in smokeless tobacco users, but the difference did not reach statistical significance (MD: -0.36; 95% CI: -0.76 to 0.04; p = 0.078).

    “Semen volume was also lower, but the difference did not reach statistical significance (MD: -0.36; 95% CI: -0.76 to 0.04; p = 0.078).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Neither reproductive hormones nor sperm DNA integrity could be meta-analyzed.

    “Reproductive hormones and sperm DNA integrity were prespecified in the eligibility criteria and the data-extraction sheet, but neither outcome could be meta-analyzed.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingown data

    Semen pH was reported in three studies (357 participants).

    “Semen pH was reported in three studies (357 participants).”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingown data

    Five studies (507 participants) reported semen volume.

    “Five studies (507 participants) reported semen volume.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingreasoning

    The evidence is not entirely consistent.

    “The evidence is not entirely consistent.”
    Quote in the paperNot a substantial claim

  • The quote only partly states this claim.

    Findingown data

    Heterogeneity for sperm concentration was substantial (I2 = 93.7%, p < 0.001).

    “Heterogeneity was substantial ( I 2 = 93.7%,p < 0.001).”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingreasoning

    Whether comparable genotoxic injury reaches the germinal epithelium has not been examined directly in the included studies.

    “Whether comparable genotoxic injury reaches the germinal epithelium has not been examined directly in the included studies.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim.

    Findingown data

    Six studies (1289 participants) reported sperm morphology.

    “Six studies (1289 participants) reported sperm morphology.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingcitation

    The findings of the two hormonal studies diverged: no significant between-group difference versus significantly higher testosterone and kisspeptin in chewers.

    “their findings diverged (no significant betweengroup difference [ 20 ] versus significantly higher testosterone and kisspeptin in chewers [ 23 ])”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [20]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [23]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Classified as probably not a substantial claim.

    Findingown data

    Sperm concentration was assessed in seven studies (1203 participants).

    “Sperm concentration was assessed in seven studies (1203 participants).”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S1 (asserted), S3 (load-bearing), S4 (based). The quote only partly states this claim.

    Findingown data

    Heterogeneity for semen volume was considerable (I2 = 92.5%, p < 0.001).

    “Heterogeneity was considerable ( I 2 = 92.5%,p < 0.001).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Study design and conductnone given

    The GRADE certainty of evidence was moderate for all pooled outcomes except semen volume, for which it was low.

    “The GRADE certainty of evidence was moderate for all pooled outcomes except semen volume, for which it was low.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Study design and conductown data

    Four studies were rated as moderate quality and 12 as high quality by ROBINS-I.

    “Four studies were rated as moderate quality, and the remaining 12 as high quality.”
    • Also stated in: § 3.2 Quality Assessment · plain
      “Four studies were rated as moderate quality and 12 as high quality (Figure 2a,b ).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationown data

    Smokeless tobacco use was associated with poorer semen quality, particularly in sperm motility, concentration, vitality, and morphology.

    “Smokeless tobacco use was associated with poorer semen quality, particularly in sperm motility, concentration, vitality, and morphology.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim. May combine two claims.

    Premisecitation

    Smokeless tobacco is a heterogeneous group of tobacco preparations used orally or nasally without combustion, and products differ markedly by region.

    “Smokeless tobacco is not a single product but a heterogeneous group of tobacco preparations that are used orally or nasally without combustion, and the products differ markedly by region.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [6]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [7]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductown data

    Two reviewers independently screened titles and abstracts, and two further reviewers independently examined full texts, with disagreements resolved through discussion and senior review.

    “In the first stage, two reviewers (O.TH and M.A.) independently screened the titles and abstracts of all retrieved studies, assessing their relevance against the predefined eligibility criteria.”
    • Also stated in: § 2.4 Screening and Data Extraction · plain
      “Studies that met the criteria, or whose eligibility remained unclear, proceeded to the second stage, in which two further reviewers (E.M. and R.Q.) independently examined the full texts.”
    • Also stated in: § 2.4 Screening and Data Extraction · plain
      “Any disagreement arising at either stage was resolved through discussion, with a senior reviewer consulted where consensus could not be reached.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Nicotine has been linked to erectile dysfunction; one study reported a significant association in men who smoked or had a past history of tobacco use.

    “Nicotine has also been linked to erectile dysfunction; one study reported a significant association in men who smoked or had a past history of tobacco use [ 4 ].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [4]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Premisecitation

    Tobacco in any form appears to impair male fertility, reducing semen quality across several measures, including sperm density, volume, motility, morphology, and viability.

    “However, tobacco in any form appears to impair male fertility, reducing semen quality across several measures, including sperm density, volume, motility, morphology, and viability.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [4]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [5]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Classified as probably not a substantial claim. May combine two claims.

    Study design and conductown data

    Potential confounders were recorded from each study during data extraction, including age, BMI, alcohol consumption, comorbidities, fertility status, occupational or environmental exposures, medication or recreational drug use, and concurrent cigarette smoking or areca-nut use, together with whether the primary comparison had been adjusted for them.

    “Potential confounders were recorded from each study during data extraction.These included age, BMI, alcohol consumption, comorbidities, fertility status and, where reported, occupational or environmental exposures, medication or recreational drug use, and concurrent cigarette smoking or areca-nut use, together with whether the primary comparison had been adjusted for them.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductcitation

    This systematic review was conducted in accordance with PRISMA 2020 guidelines and registered with PROSPERO (CRD420251056391).

    “This review was conducted in accordance with PRISMA 2020 guidelines and registered with PROSPERO (CRD420251056391).”
    • Also stated in: § 2.1 Protocol and Registration · plain
      “This systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines [ 11 ] and was registered with the International Prospective Register of Systematic Reviews (PROSPERO) under registration number CRD420251056391.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [11]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Classified as probably not a substantial claim. May combine two claims.

    Study design and conductown data

    Risk of bias was assessed with ROBINS-I and the certainty of evidence with GRADE.

    “Risk of bias was assessed with ROBINS-I and the certainty of evidence with GRADE.”
    • Also stated in: § 2.5 Quality Assessment · plain
      “The ROBINS-I tool was used to assess the methodological quality of the included studies.”
    • Also stated in: § 2.5 Quality Assessment · plain
      “Certainty of the evidence for each pooled outcome was then rated with the GRADE approach.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim. May combine two claims.

    Study design and conductown data

    Two reviewers independently assessed each included study with ROBINS-I, and disagreements were resolved through discussion and senior review.

    “Two reviewers independently assessed each study, and any disagreement between them was resolved through discussion and, where necessary, the involvement of senior reviewers.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductown data

    Four authors performed data extraction manually and independently using a pre-designed, standardized data extraction sheet.

    “Four authors (N.TH., S.Kh, N.Q., and O.TH) performed data extraction manually and independently, using a pre-designed, standardized data extraction sheet tailored to the objectives of this review.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    These findings are consistent with smokeless tobacco being an important and frequently overlooked risk factor for male infertility, although the evidence is observational and derived largely from South Asian populations.

    “These findings are consistent with smokeless tobacco being an important and frequently overlooked risk factor for male infertility, although the evidence is observational and derived largely from South Asian populations.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductcitation

    Formal tests for funnel plot asymmetry to assess publication bias were not used because each meta-analysis included fewer than 10 studies, where such tests are unreliable.

    “Formal tests for funnel plot asymmetry to assess publication bias were not used because each meta-analysis included fewer than 10 studies, where such tests are unreliable [ 13 ].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [13]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    Sensitivity was examined for sperm motility by a leave-one-out analysis, in which the pooled estimate was recalculated after omitting each study in turn.

    “Sensitivity was examined for sperm motility by a leave-one-out analysis, in which the pooled estimate was recalculated after omitting each study in turn.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim.

    Study design and conductnone given

    A systematic search of PubMed, Medline, Web of Science, and Google Scholar was performed from January 1993 to December 2025.

    “A systematic search of PubMed, Medline, Web of Science, and Google Scholar was performed from January 1993 to December 2025.”
    • Also stated in: § 2.3 Databases and Literature Search Strategy · plain
      “A comprehensive literature search was conducted across four electronic databases: PubMed, Medline, Web of Science, and Google Scholar, covering all publications from January 1993 to December 2025.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    Tobacco induces DNA fragmentation in sperm cells, which contributes to poorer sperm quality, reduced motility, compromised embryo quality, and lower fertilization rates.

    “Tobacco also induces DNA fragmentation in sperm cells, which in turn contributes to poorer sperm quality, reduced motility, compromised embryo quality, and lower fertilization rates.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [4]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [5]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Classified as probably not a substantial claim. May combine two claims.

    Study design and conductreasoning

    Confounding was addressed through the confounding domain of ROBINS-I, considered in the GRADE certainty ratings, and taken into account in the interpretation of the results.

    “Confounding was instead addressed through the confounding domain of ROBINS-I, considered in the GRADE certainty ratings, and taken into account in the interpretation of the results.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    In men, tobacco use has been associated with idiopathic infertility, elevated sperm DNA stainability, round-headed spermatozoa, and a raised sperm DNA fragmentation index.

    “In men, tobacco use has been associated with idiopathic infertility, elevated sperm DNA stainability, round-headed spermatozoa, and a raised sperm DNA fragmentation index.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [4]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [5]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Study design and conductown data

    Of the 16 cross-sectional studies included, 12 were of high quality and 4 of moderate quality.

    “(12 of high and 4 of moderate quality) included in the analysis”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Shah et al. reported total testosterone and kisspeptin in a healthy cohort.

    “Shah et al. reported total testosterone and kisspeptin in a healthy cohort [ 23 ]”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [23]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Interpretationreasoning

    The consistency of these gradients across gutkha, paan masala, snus, and toombak is consistent with the Bradford Hill criterion of biological gradient and supports the hypothesis that cumulative nicotine and nitrosamine exposure is a principal driver of toxicity.

    “The consistency of these gradients across gutkha, paan masala, snus, and toombak is consistent with the Bradford Hill criterion of biological gradient and supports the hypothesis that cumulative nicotine and nitrosamine exposure is a principal driver of toxicity.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    A Swedish population-based study reported a 24% lower total sperm count in chronic snus users despite a 14% increase in serum testosterone, which suggests an endocrine-germinal dissociation similar to that observed with chewing tobacco products.

    “A Swedish population-based study reported a 24% lower total sperm count in chronic snus users despite a 14% increase in serum testosterone, which suggests an endocrinegerminal dissociation similar to that observed with chewing tobacco products [ 31 ]”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [31]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Study design and conductreasoning

    Residual confounding by the remaining factors cannot be excluded and may account for part of the observed associations.

    “but residual confounding by the remaining factors cannot be excluded and may account for part of the observed associations.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning

    The pooled estimates chiefly reflect South Asian chewing products (gutkha, khaini, paan masala with tobacco) and Sudanese toombak, which are typically used with areca nut or slaked lime and carry nicotine and nitrosamine loads that differ from those of Scandinavian snus or nicotine pouches.

    “The pooled estimates therefore chiefly reflect South Asian chewing products (gutkha, khaini, paan masala with tobacco) and Sudanese toombak, which are typically used with areca nut or slaked lime and carry nicotine and nitrosamine loads that differ from those of Scandinavian snus or nicotine pouches.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Makki et al. reported follicle-stimulating hormone and total testosterone in infertile tobacco chewers and controls.

    “Makki et al. reported follicle-stimulating hormone and total testosterone in infertile tobacco chewers and controls [ 20 ]”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [20]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Interpretationreasoning

    The observational nature of the data and their concentration in South Asian populations mean that the findings should be interpreted with appropriate caution.

    “The observational nature of the data and their concentration in South Asian populations mean that the findings should nonetheless be interpreted with appropriate caution.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Study design and conductreasoning

    Confounding is a particular concern.

    “Confounding is a particular concern.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    In Pakistan, exclusive smokeless tobacco users had higher circulating testosterone and markedly elevated kisspeptin, yet this did not appear to preserve spermatogenesis.

    “In Pakistan, exclusive smokeless tobacco users had higher circulating testosterone and markedly elevated kisspeptin, a neuroendocrine marker of hypothalamic activation, yet this did not appear to preserve spermatogenesis [ 23 ]”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [23]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductnone given

    Reproductive hormones and sperm DNA integrity were prespecified in the eligibility criteria and the data-extraction sheet.

    “Reproductive hormones and sperm DNA integrity were prespecified in the eligibility criteria and the data-extraction sheet, but neither outcome could be meta-analyzed.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationown data

    Omission of Parmar et al. reduced heterogeneity to I2 = 81.5%, indicating that this study contributed substantially to the observed heterogeneity.

    “Omission of Parmar et al. [ 18 ] reduced heterogeneity to I 2 = 81.5%,indicating that this study contributed substantially to the observed heterogeneity (Figure 4 ).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [18]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Premisecitation

    In Egyptian chewers, seminal MDA was markedly elevated and total antioxidant capacity was reduced, in parallel with declines in sperm concentration and normal morphology.

    “In Egyptian chewers, seminal MDA was markedly elevated and total antioxidant capacity was reduced, in parallel with declines in sperm concentration and normal morphology [ 20 ]”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [20]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S2 (checkable).

    Interpretationown data

    These data challenge the widespread perception that oral tobacco is a safe alternative to smoking.

    “From a public health perspective, these data challenge the widespread perception that oral tobacco is a safe alternative to smoking.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: There is a widespread perception that oral tobacco is a safe alternative to smoking.

  • May combine two claims.

    Premisecitation

    In one Indian clinical cohort, severe chewers (more than 6 times per day) had sperm concentrations approximately 40% lower than non-chewing controls (46.25 vs. 76.6 million/mL) and approximately 18% lower than mild chewers (3 times per day or less), together with a dose-dependent decline in semen volume, total count, motility, and viability.

    “In one Indian clinical cohort, severe chewers (more than 6 times per day) had sperm concentrations approximately 40% lower than non-chewing controls (46.25 vs. 76.6 million/mL) and approximately 18% lower than mild chewers (3 times per day or less), together with a dose-dependent decline in semen volume, total count, motility, and viability [ 16 ]”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [16]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Premisecitation

    A large Indian audit of 639 infertile men reported a markedly higher prevalence of oligo-astheno-teratozoospermia (OATS, 21.8% vs. 4.3%) and azoospermia (5.8% vs. 1.4%) in chewers than in non-chewers.

    “A large Indian audit of 639 infertile men provided further support.It reported a markedly higher prevalence of oligo-astheno-teratozoospermia (OATS, 21.8% vs. 4.3%) and azoospermia (5.8% vs. 1.4%) in chewers than in non-chewers”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [26]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Premisecitation

    In the Indian audit, the most pronounced abnormalities (OATS, 34.6%; azoospermia, 26.3%) were observed in chewers with secondary infertility, consistent with cumulative exposure-related deterioration.

    “and the most pronounced abnormalities (OATS, 34.6%; azoospermia, 26.3%) were observed in chewers with secondary infertility, consistent with cumulative exposure-related deterioration [ 26 ]”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [26]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Classified as probably not a substantial claim. May combine two claims.

    Study design and conductnone given

    Several primary studies enrolled mixed tobacco-using populations; only the smokeless-specific subgroups and their controls were counted and pooled, where the data permitted.

    “Several primary studies enrolled mixed tobacco-using populations; only the smokeless-specific subgroups and their controls were counted and pooled, where the data permitted.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Study design and conductreasoning

    All included studies were observational and cross-sectional, so temporality cannot be established.

    “All included studies were observational and cross-sectional, so temporality cannot be established.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning

    Taken together, these observations suggest that the nicotine-ROS axis may account for much of the reproductive toxicity, while product-specific toxicants, such as heavy metals in toombak or additives in betel quid, may further intensify the effect.

    “Taken together, these observations suggest that the nicotine-ROS axis may account for much of the reproductive toxicity, while product-specific toxicants, such as heavy metals in toombak or additives in betel quid, may further intensify the effect.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: Smokeless tobacco delivers substantial amounts of nicotine and tobacco-specific nitrosamines directly through the oral mucosa, which promotes systemic oxidative stress.
    • Rests on an assumption: Nicotine and its metabolites may disrupt the hypothalamic-pituitary-gonadal axis.
    • Rests on an assumption: Product-specific toxicants, such as heavy metals in toombak or additives in betel quid, may further intensify the effect.

  • Classified as probably not a substantial claim. May combine two claims.

    Interpretationreasoning

    Our findings should be generalized to other regions and product types with caution and cannot be regarded as conclusive for Western users.

    “Our findings should accordingly be generalized to other regions and product types with caution and cannot be regarded as conclusive for Western users.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Genetic background, diet, environmental exposures, and laboratory practice in these settings may also differ from those elsewhere.

  • May combine two claims.

    Study design and conductown data

    Two studies reported identical control-group motility values (68.62% ± 9.94%), which may overstate the precision of that analysis.

    “Two studies reported identical control-group motility values (68.62% ± 9.94%) [ 16,18 ], which may overstate the precision of that analysis.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [16]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [18]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

55 of 55

  • The paper relies on this without support.

    The effect of smokeless tobacco on semen quality and hormonal profiles remains poorly characterized.

    “Although smokeless tobacco use is increasing worldwide, its effect on semen quality and hormonal profiles remains poorly characterized.”

  • The paper relies on this without support.

    Smokeless tobacco delivers substantial amounts of nicotine and tobacco-specific nitrosamines directly through the oral mucosa, which promotes systemic oxidative stress.

    “Smokeless tobacco delivers substantial amounts of nicotine and tobaccospecific nitrosamines directly through the oral mucosa, which promotes systemic oxidative stress.”

  • The paper relies on this without support.

    Nicotine and its metabolites may disrupt the hypothalamic-pituitary-gonadal axis.

    “Nicotine and its metabolites may also disrupt the hypothalamic-pituitary-gonadal axis.”

  • The paper relies on this without support.

    Genetic background, diet, environmental exposures, and laboratory practice in these settings may also differ from those elsewhere.

    “Genetic background, diet, environmental exposures, and laboratory practice in these settings may also differ from those elsewhere.”

  • The paper relies on this without support.

    There is a widespread perception that oral tobacco is a safe alternative to smoking.

    “these data challenge the widespread perception that oral tobacco is a safe alternative to smoking.”

  • The paper relies on this without support.

    Product-specific toxicants, such as heavy metals in toombak or additives in betel quid, may further intensify the effect.

    “while product-specific toxicants, such as heavy metals in toombak or additives in betel quid, may further intensify the effect.”
6 of 6

Cites

Flagged first, then by citations

Research works printed but not linked: 5

  1. Amor H., 2022, Studies in Family Planning
  2. Patel K., 2014, A Study on Effects of Tobacco Chewing on Various Semen Parameters, International Journal of Basic and Applied Physiology, 3, 179
  3. Makki M. A., 2017, Tobacco Chewing (Madgha) and Semen Quality, Minia Journal of Medical Research, 28, 148
  4. 10.47009/jamp.2023.5.2.158 · DOI
  5. Sharma S., 2019, The Effect of Tobacco Consumption on Semen Quality of Men Undergoing Infertility Evaluation, Journal of Pharmacy & Bioallied Sciences, 7, 98

Cited by

Still being checked.

Related

Authors
Alqarni, R., Almajed, E., Alahmari, M., Althobait, N. A., Alkathami, S. A., AlQurashi, N. N., Althobaiti, O. M., Almarzouki, A., Alotaibi, A. D., & Zugail, A. S.
Affiliations
  • Imam Mohammad ibn Saud Islamic University (SA)
  • Riyadh Armed Forces Hospital (SA)
  • Taif University (SA)
  • King Fahd Medical City (SA)
  • Armed Forces Hospital (SA)
  • Ollscoil na Gaillimhe – University of Galway (IE)
  • King Abdulaziz University (SA)
Corresponding author
Alqarni, Rayan
ORCID
Venue
Andrology
Publisher
Wiley
Published
2026-10-04
ISSN
  • 2047-2919 (ISSN-L)
  • 2047-2927
DOI
10.1111/andr.70394
OpenAlex
W7219746636
Semantic Scholar
51a566b8cbc43619633751cb1646293145192f29
Cited by
0
References
19
FWCI
0.00
Type
journal article
Language
en
Open access
Licence
Locations
  • Andrology (publishedVersion)
  • PubMed (publishedVersion)
Topics
  • Health Sciences › Medicine › Reproductive Medicine › Sperm and Testicular Function
  • Health Sciences › Medicine › Physiology › Smoking Behavior and Cessation
  • Health Sciences › Health Professions › General Health Professions › Male Reproductive Health Studies
Keywords
semen quality, male infertility, sperm motility, sperm concentration, sperm viability, sperm morphology, semen pH, semen volume, male reproductive health, tobacco use risk factors, South Asian populations, smoking cessation counseling, tobacco advertising restrictions, tobacco product regulation

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-11-06.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-11-06.

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