Bioavailability of red wine anthocyanins as detected in human urine

Anthocyanins, which are natural plant pigments from the flavonoid family, represent substantiated constituents of the human diet. Many foods but especially red grapes and wines contain large amounts of flavonoids, which are mostly anthocyanins. The aim of our study was to determine the potential bioavailability, in human, of several anthocyanins from red wine. Six healthy, fasting volunteers, having a polyphenols-free diet, drank 300 mL of water every hour for 12 h and collected urine. Several weeks later, the same volunteers repeated the same procedure but replaced the water of the fourth drinking dose with white wine. Two weeks later, they repeated the procedure with red instead of white wine. In the 300 mt dose of red wine, the subjects received 218 mg of anthocyanins, which were detected in their urine by HPLC analysis with a photodiode array detector. Two of the compounds found among the wine anthocyanins were found unchanged in the urine. Other anthocyanin compounds, which seemed to have undergone molecular modifications, were detected in the urine after incubation with HCl. The anthocyanin level in the urine reached a peak within 6 h of the wine drinking. Within 12 h of the wine drinking, we found 1.5-5.1% of the ingested anthocyanins, in the urine.