Coffee drinking and serum gamma-glutamyltransferase: an extended study of Self-Defense Officials of Japan

Ann Epidemiol. 1999 Jul;9(5):325-31. doi: 10.1016/s1047-2797(99)00013-7.


Purpose: To examine the effect of coffee drinking on serum gamma-glutamyltransferase (GGT) level in relation to alcohol drinking, smoking, and degree of obesity in middle-aged Japanese men.

Methods: From 1986 to 1994, a total of 7,637 male officials of the Self-Defense Forces of Japan aged 48-59 years received a preretirement health examination. Coffee drinking was ascertained by a self-administered questionnaire, and serum GGT level was measured. After excluding 1,360 men with a possible pathologic condition influencing liver enzyme levels and 182 former alcohol drinkers, effect of coffee drinking on serum GGT was examined by a multiple linear regression model and analysis of variance adjusting for alcohol drinking, smoking, and body mass index (BMI).

Results: The adjusted percentage of difference in serum GGT was -4.3 (95% CI = -5.0; -3.5) per cup of coffee. The inverse coffee-GGT relation was most prominent among men drinking > or = 30 ml of ethanol and smoking > or = 15 cigarettes daily; and positive associations of alcohol and smoking with GGT were attenuated by coffee drinking, more clearly among men with BMI > or = 25.00 kg/m2. Adjusted percentages of difference in serum GGT were -2.6% (p = 0.0003) per cup of brewed coffee, and -5.1% (p = 0.0001) per cup of instant coffee, independently of each other.

Conclusions: The present study suggests that coffee consumption may weaken GGT-induction by alcohol, and possibly by smoking. These effect modifications by coffee may differ according to the degree of obesity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alcohol Drinking / blood
  • Body Mass Index
  • Coffee*
  • Humans
  • Japan / epidemiology
  • Linear Models
  • Male
  • Middle Aged
  • Smoking / blood
  • Surveys and Questionnaires
  • gamma-Glutamyltransferase / blood*


  • Coffee
  • gamma-Glutamyltransferase