3 research outputs found
Urolithins Are the Main Urinary Microbial-Derived Phenolic Metabolites Discriminating a Moderate Consumption of Nuts in Free-Living Subjects with Diagnosed Metabolic Syndrome
Walnuts (Juglans regia L.), hazelnuts
(Corylus avellana L.), and almonds
(Prunus dulcis Mill.) are rich sources
of ellagitannins and proanthocyanidins. Gut microbiota plays a crucial
role in modulating the bioavailability of these high molecular weight
polyphenols. However, to date there are no studies evaluating the
capacity to produce nut phenolic metabolites in subjects with metabolic
syndrome (MetS), a pathology associated with an altered gut bacterial
diversity. This study applied a LC-MS targeted approach to analyze
the urinary excretion of nut phenolic metabolites in MetS subjects
following 12 weeks of nut consumption, compared to sex- and age-matched
individuals given a nut-free control diet. Metabolites were targeted
in both hydrolyzed and nonhydrolyzed urine by LC-PDA-QqQ-MS/MS analysis,
and identification of metabolites lacking available standards was
confirmed by LC-ESI-ITD-FT-MS. Ellagitannin-derived urolithins A and
B significantly increased after the nut-enriched-diet, urolithins
C and D were also detected, and a complex combination of urolithin-conjugated
forms was observed in nonhydrolyzed urine, confirming an extensive
phase II metabolism after absorption. In contrast, no significant
increases in proanthocyanidin microbial metabolites were observed
in urine following nut consumption. Because the intestinal microbiota
of the subjects in this study could catabolize ellagitannins into
a wide range of urolithins, further research is strongly warranted
on the in vivo potential of these microbial metabolites in reducing
cardiometabolic risk