Title
Increased probiotic or prebiotic (resistant starch) intake does not significantly affect isoflavone bioavailability in subjects consuming a high soy diet.
Document Type
Journal Article
Publication Date
October 2007
Abstract
Objective: Probiotics and prebiotics that affect gut microflora balance and its associated enzyme activity may contribute to inter-individual variation in isoflavone absorption following soy intake, possibly enhancing isoflavone bioavailability. This study examined the effects of the consumption of a probiotic (bioactive yogurt) or a prebiotic (resistant starch) in combination with high soy intake, on soy isoflavone bioavailability. Research Methods and Procedures: Using a crossover design, chronic soy consumption was compared with soy plus either probiotic or prebiotic foods in older male and postmenopausal females (n = 31). Isoflavone bioavailability was assessed at the beginning and end of each 5 week dietary period by sampling plasma and urine after a standardized soy meal. Results: Chronic soy intake did not significantly affect plasma or urinary isoflavones following the soy meal and there were no significant effects of either probiotic or prebiotic treatment. However, there were trends for increased circulating plasma daidzein and genistein after the probiotic treatment and for increased plasma daidzein and genistein 24 h post soy intake with the prebiotic treatment. Neither probiotic nor prebiotic treatment induced or increased equol production, though there was a trend for increased plasma equol in “equol-positive” subjects (n = 12) after probiotic treatment. Conclusion: The weak or absence of effects of probiotic or prebiotic supplement to a chronic soy diet suggests that gut microflora were not modified in a manner that significantly affected isoflavone bioavailability or metabolism.
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Publication Details
This article was originally published as Larkin, TA, Price, WE, Astheimer, L, Increased probiotic or prebiotic (resistant starch) intake does not significantly affect isoflavone bioavailability in subjects consuming a high soy diet, Nutrition, 23(10), 2007, 709-718. The original article is available here.