Bioavailability and metabolism of phenolic compounds from wholegrain wheat and aleurone-rich wheat bread

Scope: This work aimed at investigating absorption, metabolism, and bioavailability of phenoliccompounds after consumption of wholegrain bread or bread enriched with an aleurone fraction.Methods and results: Two commercially available breads were consumed by 15 participants onthree occasions and matched for either the amount of ferulic acid in the bread or the amount ofbread consumed. Urine was collected for 48 h from all the volunteers for phenolic metabolitequantification. Blood samples were collected for 24 h following bread consumption in five par-ticipants. A total of 12 and 4 phenolic metabolites were quantified in urine and plasma samples,respectively. Metabolites were sulfate and glucuronic acid conjugates of phenolic acids, andhigh concentrations of ferulic acid-4’-O-sulfate, dihydroferulic acid-4’-O-sulfate, and dihydro-ferulic acid-O-glucuronide were observed. The bioavailability of ferulic acid was significantlyhigher from the aleurone-enriched bread when all ferulic acid metabolites were accounted for.Conclusions: The study shows that low amounts of aleurone-enriched bread resulted in equiv-alent plasma levels of ferulic acid as wholegrain bread. This could suggest that, if the absorbedphenolic metabolites after wholegrain product intake exert health benefits, equal levels couldbe reached through the consumption of lower doses of refined products enriched in aleuronefraction.