**3.3 The extent of metabolism of flavonoids**

Flavonols were the initial to be examined, and human urine excretion was found to be quite modest. Only 0.1 percent to 3.6% of quercetin in the diet was eliminated in urine as quercetin conjugates. The sum of complete quercetin in blood plasma will be correlated with urinary excretion. Because the fascination of quercetin glucosides is high (up to 50%), while the evacuation of whole quercetin in urine is low, this indicates that quercetin undergoes substantial metabolism. Additional subclasses were investigated with helpers, and urine evacuation of metabolites with intact flavonoid structures was measured. Isoflavones have the highest rate of excretion of all flavonoids. Although isoflavones have a high bioavailability, flavonols glucosides have a higher bioavailability but a lower urine elimination. This would suggest that with isoflavones, the ring arrangement's metabolic modification level is less than through flavonols.
