Prediction of dietary flavonol consumption from fasting plasma concentration or urinary excretion

to predict flavonols content of the habitual diets of free-living subjects from urine and plasma concentrations of flavonols. Ten type 2 diabetic patients (five male, five female), mean age 60 (s.e.m. 7) y and BMI 30.2 (s.e.m. 3.5) kg/m2 were treated in a random crossover design for a 2 week period on either a low flavonoid diet or on the same diet supplemented at one of two high flavonols levels (total 77.3 or 110.4 mg/day) provided by supplements of 1500 ml tea daily and 400 g fried white onion in olive oil with and without tomato ketchup and herbs. Glasgow Royal Infirmary, University of Glasgow, Scotland. Fasting plasma concentration, urine concentration and 24 h excretion of quercetin, isorhamnetin, kaempferol and myricetin. Plasma flavonol concentration (r=0.750, P=0.001), 24 h urine concentration (r=0.847, P=0.001) and 24 h urine excretion (r=0.728, P=