Additive effects of moderate drinking and obesity on serum γ-glutamyl transferase activity

Background: γ-Glutamyl transferase (GGT) is a widely used index of liver induction and a marker of alcohol overconsumption. Obesity has also been suggested to elevate serum GGT activities. Objective: The aim was to examine the links between moderate ethanol consumption, obesity, and GGT activities. Design: GGT values were recorded from 2490 persons (1184 men and 1306 women) who reported either no alcohol use (abstainers) or 1-40 g ethanol consumption per day (moderate drinkers). The study population was additionally classified according to body mass index (BMI; in kg/m2) as follows: <19 (underweight), ≥19 and <25 (normal weight), ≥25 and <30 (overweight), and ≥30 (obese). Results: Significant main effects of sex (P < 0.0001), drinking habits (P < 0.01), and BMI (P < 0.001) on serum GGT activities were observed. The values were higher in the men than in the women and higher in those with higher BMIs. The highest activities were found to occur in persons with moderate drinking combined with overweight or obesity. A significant positive correlation between GGT and BMI (P < 0.0001) was observed, which was stronger for the men (r = 0.24) than for the women (r = 0.15, P < 0.05 for the difference between correlations). Conclusion: The data indicate that serum GGT activities may respond to moderate drinking and overweight in an additive manner; this should be considered in the clinical use of GGT measurements and when defining normal GGT values in health care.