This study evaluated the effect of ingesting a flavonoid-rich supplement (329 mg/d) on total urine phenolics and shifts in plasma metabolites in overweight/obese female adults using untargeted metabolomics procedures. Participants (N = 103, 18-65 y, BMI ≥ 25 kg/m2) were randomized to flavonoid (F) or placebo (P) groups for 12 weeks with blood and 24 h urine samples collected prestudy and after 4 and 12 weeks in a parallel design. Supplements were prepared as chewable tablets and included vitamin C, wild bilberry fruit extract, green tea leaf extract, quercetin, caffeine, and omega 3 fatty acids. At 4 weeks, urine total phenolics increased 24% in F versus P with similar changes at 12 weeks (interaction effect, P = 0.041). Groups did not differ in markers of inflammation (IL-6, MCP-1, CRP) or oxidative stress (oxLDL, FRAP). Metabolomics data indicated shifts in 63 biochemicals in F versus P with 70% from the lipid and xenobiotics superpathways. The largest fold changes in F were measured for three gut-derived phenolics including 3-methoxycatechol sulfate, 3-(3-hydroxyphenyl)propanoic acid sulfate, and 1,2,3-benzenetriol sulfate (interaction effects, p ≤ 0.050). This randomized clinical trial of overweight/obese women showed that 12 weeks ingestion of a mixed flavonoid nutrient supplement was associated with a corresponding increase in urine total phenolics and gut-derived phenolic metabolites.
Keywords: dietary supplement; metabolomics; obesity; polyphenol.