The Rostock red wine study: the impact of alcohol on the detoxification capacity of the liver measured by [13C]methacetin- and [methyl-13C]methionine-breath tests

Introduction: A great number of different ¹³C-labelled substrates have been evaluated to explore the harmful effects of alcohol consumption on specific hepatic functions. After degradation of the ¹³C-tracers, the resulting ¹³CO₂ exhaled in breath reflects the detoxification capacity of the liver.

The aim of this study was to investigate the hepatic microsomial and mitochondrial functions by using the ¹³CO₂-breath test in healthy adults before and after the consumption of red wine.

Methods: In a cross-over study 14 healthy adults received [¹³C]methacetin- and [methyl-¹³C]methionine in a dosage of 2mg/kg body weight together with a standardised continental dinner. Expired air samples were taken over 7h. After a wash-out period of 5 days the subjects consumed 0.4ml ethanol/kg/day equivalent to 3.5ml red wine/kg/day (dry Bordeaux, 11.5 vol-%) together with dinner over a time-span of 10 days. Thereafter, the ¹³C-tracer administration was repeated under identical conditions. The ¹³CO₂-enrichments were measured by non-dispersive infrared spectroscopy.

Results: The mean cumulative percentage dose recovery (CPDR) 7 hours after administration of [¹³C]methacetin- and [methyl-¹³C]methionine without and with red wine consumption amounted to 40.0±3.2 vs. 36.9±5.8% (p=0.08) and 10.4±3.9 vs. 9.4±3.1% (p=0.28), respectively. Red wine drinking led to decreased but not statistically different CPDR values.

Conclusions: In the present study ¹³CO₂-breath tests with [¹³C]methacetin- and [methyl-¹³C]methionine have been used for non-invasive measurements of the hepatic function before and after ethanol-induced oxidative stress. The data show that moderate alcohol consumption of 0.4ml/kg/day over a 10-days period does not induce significant short-term changes of the microsomial and the mitochondrial function of the human liver in healthy subjects. The different metabolic fate of [¹³C]methacetin representing xenobiotics and [methyl-¹³C]methionine representing a sulphur containing essential amino acid could be clearly demonstrated by comparing the CPDR values (40.0 vs. 10.4%, respectively). Our combination of measuring the oxidative capacity of the liver after a relatively short period of red wine drinking together with food intake is a novelty.