High serum carotenoids are inversely associated with serum gamma-glutamyltransferase in alcohol drinkers within normal liver function

BACKGROUND: Many studies have reported that the consumption of alcohol induces the generation of free radicals. Moreover, recent studies suggest that serum gamma-glutamyltransferase (gamma-GTP) within its normal range might be an early marker of oxidative stress. In this study, we tested the hypothesis that serum antioxidant carotenoids would be inversely associated with serum gamma-GTP in alcohol drinkers within normal liver function. METHODS: A total of 266 Japanese men who had received health examination in 2003 participated in the study. The associations of serum gamma-GTP and serum-carotenoid concentrations stratified by alcohol intake levels were evaluated cross-sectionally. The participants were divided into three groups according to their ethanol intake level (non-drinker, less than 1 g/day; light drinker, 1-25 g/day; and moderate and heavy drinkers, 25+ g/day). The multivariate-adjusted geometric means of the serum gamma-GTP concentrations in each tertile of the serum-carotenoid concentrations were calculated after adjustment for ethanol intake, age, body mass index, total cholesterol, triacylglycerols, current tobacco use, and habitual exercise. RESULTS: The serum gamma-GTP concentrations were significantly high in accordance with the ethanol intake level. In moderate and heavy drinkers, the multivariate-adjusted geometric means of serum gamma GTP concentrations were significantly low in accordance with the tertiles of the serum lycopene, a carotene, beta-carotene, and beta-cryptoxanthin concentrations. CONCLUSIONS: The serum antioxidant carotenoids were inversely associated with alcohol-induced increases of serum gamma-GTP in moderate and heavy drinkers within normal liver function.