Lifestyle and the development of increased serum gamma-glutamyltransferase in middle-aged Japanese men.

To identify the lifestyle factors responsible for increases in serum gamma-glutamyltransferase (GGT), 1014 hepatobiliary dysfunction-free (no medication for and no past history of liver disease, < or = 39 U/L of serum aspartate and/or alanine aminotransferase, and < or = 59 U/L of serum GGT) Japanese male office workers aged 35-55 years were examined annually over five successive years (average period 4.5 years, SD 1.11 years). From the Cox proportional hazards model without serum GGT at entry, significant correlates with the incidence of increased (> or = 60 U/L) serum GGT levels were the slope of body mass index (BMI), alcohol intake, cigarette smoking and coffee drinking (negative). In the model including serum GGT at entry, the slope of BMI and coffee drinking (negative) remained as significant factors for the incidence of increased serum GGT levels. From stepwise regression analyses for the slope of log serum GGT at entry, not including serum GGT in the model, significant correlates with the slope of serum GGT were, in order of relative importance, the slope of BMI, alcohol intake and coffee drinking (negative). In the model with serum GGT at entry, the slope of BMI and coffee drinking (negative) remained as statistically significant. Our results indicate that an increase in body weight is the strongest determinant for increases in serum GGT and that coffee drinking may be associated with a reduced risk of the development of increased serum GGT levels.