QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Zheng, Y. Articles by Hendrich, S. Search for Related Content PubMed PubMed Citation Articles by Zheng, Y. Articles by Hendrich, S.

---

Human Nutrition and Metabolism

Rapid Gut Transit Time and Slow Fecal Isoflavone Disappearance Phenotype Are Associated with Greater Genistein Bioavailability in Women^1,2

Yan Zheng^*,, Jiang Hu^*,, Patricia A. Murphy^*,, D. Lee Alekel^*,, Warren D. Franke^** and Suzanne Hendrich^*,,3

^* Department of Food Science and Human Nutrition, Human Metabolic Unit, Center for Designing Foods to Improve Nutrition, and ^** Department of Health and Human Performance, Iowa State University, Ames, IA 50011

³To whom correspondence should be addressed. E-mail: shendric{at}iastate.edu.

The bioavailability of soybean isoflavones varies widely among individuals due to many factors, including activities of gut microflora. To characterize factors that affect fecal isoflavone disappearance phenotype and isoflavone bioavailability in women, 35 Asian and 33 Caucasian women, 18–43 y of age, provided fecal samples for anaerobic incubation with isoflavones in vitro at two times 5 mo apart (Phases I and II). Diet, physical activity and health history were investigated at these times. A single dose of soymilk powder [1.2 mg (4.57 µmol) total isoflavone/kg body] was given to all subjects with breakfast in phase II. Daidzein and genistein from fecal incubations, urine and fecal samples were measured by reverse-phase HPLC. Three significantly different daidzein and two genistein disappearance phenotypes were identified from fecal isoflavone incubations. More Asians than Caucasians were identified within the high daidzein disappearance phenotype. Caucasians and Asians differed significantly in daily intake of red meat (0.3 ± 0.1 vs. 1.0 ± 0.1 servings/d), dairy foods (2.9 ± 0.2 vs. 1.2 ± 0.2 servings/d) and insoluble dietary fiber (3.6 ± 0.3 vs. 1.4 ± 0.3 g). BMI, maximal oxygen uptake (VO_{2 max}) and physical activity level were significantly greater in Caucasians than in Asians. Asian subjects of the low genistein disappearance phenotype had more rapid gut transit time (GTT) and greater isoflavone bioavailability as reflected in urinary genistein excretion than did Asians of the high genistein disappearance phenotype (GTT, 40 ± 8 vs. 63 ± 5 h; 11.0 ± 2.7 vs. 4.0 ± 1.7% of ingested genistein excreted in urine). Caucasians of both genistein disappearance phenotypes had longer GTT than did Asian subjects (84 ± 5 vs. 56 ± 6 h) and resembled Asians of the high genistein disappearance phenotype in genistein bioavailability. Relatively rapid GTT coupled with a low fecal isoflavone disappearance phenotype as occurred in Asian but not Caucasian subjects produced greater genistein bioavailability, as reflected in urinary genistein excretion.

KEY WORDS: • isoflavone • genistein • degradation • gut transit time • ethnicity

This article has been cited by other articles:

				Z. Ye, M. Renouf, S.-O. Lee, C. C. Hauck, P. A. Murphy, and S. Hendrich High Urinary Isoflavone Excretion Phenotype Decreases Plasma Cholesterol in Golden Syrian Hamsters Fed Soy Protein J. Nutr., November 1, 2006; 136(11): 2773 - 2778. [Abstract] [Full Text] [PDF]