Individual variability in polyphenol metabolite production: A dietary challenge study

BackgroundPolyphenols are metabolites of a variety of foods, mostly plant-based, that possess beneficial effects on metabolic health, largely through antioxidant and anti-inflammatory mechanisms. Beneficial associations between polyphenol-rich foods and metabolic health are well established, but individual differences in polyphenol metabolism exist and contribute to inconsistent relationships between plasma polyphenols and health outcomes. Characterizing differences in urinary polyphenol metabolite production may hold implications for studies of urinary polyphenol concentrations and advance understanding of the heterogeneity that exists in response to dietary interventions. MethodsEligible participants were recruited from the Kannapolis, NC area and underwent a controlled dietary challenge. Participants collected time-stamped urine samples for 24-hours after consumption of capsules containing soy isoflavone extract, flaxseed hull extract, pomegranate juice, and choline bitartrate. Urine samples were kept in coolers for delivery to the Nutrition Research Institute (NRI). Prior to the challenge, participants consumed meals low in polyphenols designed by the Metabolite core. Mass spectrometry quantified polyphenol metabolites from time-stamped urine samples. Metabolite concentrations were transformed to area under the curve (AUC) and maximum output variables, for total urine and 8-hr increments. Participants were grouped by tertile of metabolite output for each variable. Agreeance between metabolite output tertiles for each variable was assessed to identify consistency in measures. ConclusionsIn a likely homogenous sample of adults, we noted significant variability in polyphenol metabolite production in response to a controlled dietary challenge. In addition, there was generally low agreement between tertiles of metabolite output variables, holding implications for studies using time-specific metabolite measures, rather than 24-hr AUC.