Background & aims: Dietary polyphenols, including anthocyanins, are suggested to be involved in the protective effects of red wine against cardiovascular diseases. Very little data are available concerning the bioavailability of anthocyanins, major sources of red pigmentation in red wine. The aim of this study was to compare changes in plasma malvidin-3-glucoside (M-3-G), a red wine anthocyanin, and its urinary excretion after ingestion of red wine, dealcoholized red wine and red grape juice.
Design: Six healthy male subjects were studied in a randomized cross over setting in a human nutrition research unit under controlled conditions. All subject consumed 500 mL of each beverage on separate days providing the following M-3-G quantities: red wine 68 mg, dealcoholized red wine 58 mg, and red grape juice 117 mg. M-3-G was measured by HPLC and photodiode detection.
Results: M-3-G was found in plasma and urine after ingestion of all the beverages studied. The aglycon, sulfate or glucuronate conjugates of M-3-G were not detected in plasma and urine. Increases in plasma M-3-G concentrations were not significantly different after the consumption of either red wine or dealcoholized red wine and were about two times less than those measured after consumption of red grape juice. This difference may be caused by the about two times higher M-3-G concentration determined in red grape juice. Area under the plasma concentration curves were as follows: 288 +/- 127 nmol x h/L (red wine), 214 +/- 124nmol x h/L (dealcoholized red wine) and 662 +/- 210 nmol x h/L (red grape juice) and showed a linear relationship with the amount of anthocyanin consumed (mean +/- SD).
Conclusions: M-3-G is poorly absorbed after a single ingestion of red wine, dealcoholized red wine, or red grape juice and seems to be differentially metabolized as compared to other red grape polyphenols. Our results suggest that not anthocyanins such as M-3-G themselves but rather not yet identified anthocyanin metabolites and/or other polyphenols in red wine might be responsible for the observed antioxidant and health effects in vivo in subjects consuming red wine.