Non-Alcoholic Fatty Liver Disease Modifies Serum Gamma-Glutamyl Transferase in Cigarette Smokers

Ebenezer T. Oni, Vincent Figueredo, Ehimen Aneni, Emir Veladar, John W. McEvoy, Michael J. Blaha, Roger S. Blumenthal, Raquel D. Conceicao, Jose A.M. Carvalho, Raul D. Santos, Khurram Nasir

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Background: Serum gamma-glutamyl transferase (GGT) is a marker of oxidative stress, associated with increased cardiovascular (CV) risk. The impact of smoking on oxidative stress may be aggravated in individuals with non-alcoholic fatty liver disease (NAFLD). We aimed to ascertain the association of smoking on GGT levels in the presence or absence of NAFLD. Methods: We evaluated 6,354 healthy subjects (43 ± 10 years, 79% males) without clinical cardiovascular disease (CVD) undergoing an employer-sponsored physical between December 2008 and December 2010. NAFLD was diagnosed by ultrasound and participants were categorized as current or non-smokers by self report. A multivariate linear regression of the cross-sectional association between smoking and GGT was conducted based on NAFLD status. Results: The prevalence of NAFLD was 36% (n = 2,299) and 564 (9%) were current smokers. Smokers had significantly higher GGT levels in the presence of NAFLD (P < 0.001). After multivariable adjustment, current smoking was associated with 4.65 IU/L higher GGT level, P < 0.001, compared to non-smokers. When stratified by NAFLD, the magnitude of this association was higher in subjects with NAFLD (β-coefficient: 11.12; 95% confidence interval (CI): 5.76 - 16.48; P < 0.001); however, no such relationship was observed in those without NAFLD (β: -0.02; 95% CI: -3.59, 3.56; P = 0.992). Overall the interaction of NAFLD and smoking with GGT levels as markers of oxidative stress was statistically significant. Conclusions: Smoking is independently associated with significantly increased oxidative stress as measured by GGT level.

Original languageEnglish (US)
Pages (from-to)472-482
Number of pages11
JournalJournal of Clinical Medicine Research
Issue number8
StatePublished - 2020


  • Cardiovascular risk
  • Gamma-glutamyl transferase
  • Non-alcoholic fatty liver disease
  • Oxidative stress
  • Smoking

ASJC Scopus subject areas

  • Medicine(all)


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