Mean plasma concentrations of resveratrol (A),resveratrol-4′-O-glucuronide (B), resveratrol-3-O-glucuronide (C) and resveratrol-3-O-sulfate (D) versus time in healthy volunteers after the last of between 21 and 28 daily doses of resveratrol at either 0.5g (black, closed circles), 1g (green, open circles), 2.5g (blue, squares) or 5g (red, triangles). Values are the mean±SD of 10 volunteers per dose level. The range of coefficients of variation (as % of the mean) for the individual data points is shown in brackets.