This study was aimed to investigate the urine kinetics of isoflavones after oral intake of soymilk in healthy adults in Taiwan. Nine
volunteers received 800 mL of soymilk equivalent to 200 g of soybeans and the urine were collected from 0 to 48 h. Daidzein, equol and genistein in urine were assayed by HPLC before and after hydrolysis with β-glucuronidase and sulfatase. The results revealed that the parent forms of daidzein and genistein were not detected in the urine with major forms being the glucuronides (G) and sulfates (S), mainly G. Besides, equol G and S, the metabolites of daidzein, were detected in the urine of all subjects. In conclusion, G and S of daidzein and genistein, mainly G, were excreted in the urine of healthy adults in Taiwan after ingestion of soymilk. In addition, G and S of equol were found in urine of all nine subjects.