Consumption frequency of stinky tofu and urine isoflavone kinetic analysis after a single ingestion of stinky tofu

• Main Authors: Jo-Han Tu, 屠若涵
• Other Authors: Wen-Huey Wu
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/29632740413246057255

碩士 === 國立臺灣師範大學 === 人類發展與家庭學系 === 100 === This research analyzed isoflavones content in stinky tofu from night markets in Taipei and Taichung, consumption frequency of stinky tofu by hobbyists, and urinary pharmacokinetics of isoflavones following a single ingestion of stinky tofu by equol producers and non-producers. We collected 143 stinky tofu samples from 122 vendors and analyzed the isoflavones content by HPLC (high-performance liquid chromatography). The results showed that the average contents in every 100 g of stinky tofu were 9.32 mg of daidzein (including glycosides 3.81 mg and aglycon 5.51 mg), 12.81 mg of genistein (including glycosides 6.31 mg and aglycon 6.50 mg), 1.27 mg of glycitein (including glycosides 0.39 mg and aglycon 0.88 mg), 0.36 mg of dihydrodaidzein, 1.16 mg of equol, 0.01 mg of desmethylangolesin, and 0.55 mg of dihydrogenistein. The percentage of aglycone isoflavone is 49.7±27.2. We also surveyed 274 respondents with habit of eating stinky tofu for their stinky tofu intake frequency. We found that 18.3% of the respondents take more than 1–2 times per week, 46.4% of them take 1–3 times per month, and 24.8% of them take 1–2 times per quarter. The average amount of each intake is 195.0± 79.6 g. We recruited 74 stinky tofu hobbyists within 20–30 years old and analyzed their equol content in urine after challenging soy isoflavone for 3 days, that were identified 52 of them (70.3%) are equol producers and 22 of them (29.7%) are equol non-producers. We selected 20 equol producers and 18 equol non-producers, collect their urine in the 48 hours after one serving of stinky tofu (four 1-hour urine samples, four 2-hour urine samples and three 12-hour urine samples), and analyzed urinary isoflavone content. We found that daidzein, equol, genistein and glycitein were excreted within 0–1 hour, and it reached peak excretion rate after 3–4 hours. The excretion amount approached 0 after 36–48 hours. Dihydrodaidzein and desmethylangolesin started to be excreted 1–4 after serving stinky tofu, and it reached peak excresion rate in 10–12 hours. The difference of daidzein, equol and genistein excretion amount and rate between equol producers and non-producers appeared to be significant in 10–12 hours; the difference of dihydrodaidzein and desmethylangolesin appeared to be significant in 12–24 hours. That means, the metabolites of daidzein and genistein in stinky tofu appeared 10 hours after intaking. The excretion amount and rate difference of glycitein between equol producers and non-producers was insignificant within 0–48 hours. Recovery of urine isoflavones is 75.9 % of total daidzein, 67.4 % of equol, 41.8 % of total genistein and 65.3 % of total glycitein. The equol producers had similar amount of soy food intake, stinky tofu intake and defecation frequency as compared with the equol non-producers. Our results show that the aglycone isoflavones content in stinky tofu are rich, especially containing equol. And the absorption rates are high for both equol producers and non-producers. Stinky tofu could serve as an equol source. It requires further research to justify if the proportion of equol producers is higher among young stinky tofu hobbyists.