SCOPE: Wholegrain has been associated with reduced chronic disease mortality, with oat intake particularly notable for lowering blood cholesterol and glycemia. To better understand the complex nutrient profile of oats, we studied urinary excretion of phenolic acids and avenanthramides after ingestion of oat bran in humans.
METHODS AND RESULTS: After a 2d (poly)phenol-low diet, 7 healthy men provided urine 12h before, and 48h after, consuming 60g oat bran (7.8μmol avenanthramides, 139.2μmol phenolic acids) or a phenolic-low (traces of phenolics) control in a crossover design. Analysis by UPLC-MS/MS showed that oat bran intake resulted in an elevation in urinary excretion of 30 phenolics relative to the control, suggesting that they are oat bran-derived. Mean excretion levels were elevated between 0-2 and 4-8h, following oat bran intake, and amounted to a total of 33.7 ± 7.3μmol total excretion (mean recovery: 22.9 ± 5.0%), relative to control. The predominant metabolites included: vanillic acid, 4- and 3-hydroxyhippuric acids and sulfate-conjugates of benzoic and ferulic acids, which accounted collectively for two thirds of total excretion.
CONCLUSION: Oat bran phenolics follow a relatively rapid urinary excretion, with 30 metabolites excreted within 8h of intake. These levels of excretion suggest that bound phenolics are, in part, rapidly released by the microbiota.
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- School of Life and Health Sciences - Senior Lecturer
- Centre for Integrated Research in Life and Health Sciences