Avenacosides: Metabolism, and potential use as exposure biomarkers of oat intake

Scope: Exposure biomarkers used for objective estimation of whole-grain (WG) intake are essential for epidemiologic studies of WG consumption, however, up to now, no exposure biomarkers were developed for WG oat intake. This study investigates the potential of oat unique components, Avenacoside-B (AVE-B) and –A (AVE-A), as exposure biomarkers of oat intake. Methods and results: An in vivo study performed in mice and an in vitro batch fecal fermentation study were used to investigate the potential metabolic routes of AVE-B and -A. Twelve healthy volunteers were recruited in the human urinary pharmacokinetic study, each participant received a single dose of oat bran as breakfast, 48 h urine samples were collected at baseline and after treatment period, and AVE-B and -A were quantified by LC-MS/MS. Deglycosylation metabolic route was identified as the major metabolic path for AVE-B and -A. Urinary AVE-B and -A concentrations increased rapidly after oat ingestion, reached their maximum excretion rates (ER_max) fairly simultaneously within 5 h, then decreased gradually. And the mean eliminate half-lives (T_1/2) for AVE-B and -A were determined as 6.22 and 4.55 h, respectively. Conclusion: Oat AVE-B and -A have great potential to be used as specific exposure biomarkers to reflect oat intake.