Flavonol glycosides of sea buckthorn (Hippophaë rhamnoides ssp. sinensis) and lingonberry (Vaccinium vitis-idaea) are bioavailable in humans and monoglucuronidated for excretion.

Glucuronidation and excretion of sea buckthorn and lingonberry flavonols were investigated in a postprandial trial by analyzing the intact forms of flavonol glycosides as well as glucuronides in plasma, urine, and feces. Four study subjects consumed sea buckthorn (study day 1) and lingonberry (study day 2) breakfasts, and blood, urine, and fecal samples were collected for 8, 24, and 48 h, respectively. Both glycosides and glucuronides of the flavonol quercetin as well as kaempferol glucuronides were detected in urine and plasma samples after the consumption of lingonberries; 14% of flavonols in urine were glycosides, and 86% were glucuronidated forms (wt %).