There is considerable interest in coloured fruits and berries as sources of biologically active
anthocyanins. To examine the relationship between the oral dose and the amount
excreted for
anthocyanins from a food source across a physiological range of doses, volunteers were fed, in
random order, four portions (100-400 g) of fresh strawberries as part of a standard breakfast.
Urine was collected at 2 h intervals up to 8 h, and for the period 8-24 h. Fresh strawberries contained pelargonidin-3-glucoside as the major
anthocyanin with smaller amounts of cyanidin-3-glucoside and pelargonidin-3-rutinoside.
Anthocyanins were detected in the
urine of all volunteers for all doses, predominantly as
pelargonidin glucuronide and
sulphate metabolites. There was a strong, linear relationship between oral dose and
anthocyanin excretion (Pearson's
product moment correlation coefficient = 0.692, p < 0.001, n = 40) which indicated that on an
average, every additional unit of dose caused 0.0166 units of
excretion. Within individuals, dose --
excretion data fitted a
linear regression model (
median R(2) = 0.93). We conclude that strawberry
anthocyanins are partially
bioavailable in humans with a linear relationship between oral dose and
urinary excretion for doses up to 400 g fresh fruit.
