Purpose: In this study, we investigated the absorption and excretion kinetics of antioxidant dietary phytochemicals (vitamin E, γ-oryzanol, and ferulic acid) in healthy humans after the ingestion of an oatmeal porridge supplemented with rice bran extract (RBE) prepared with water or with whole milk, and we compared it with the intake of an equivalent dose of the rice bran content, in the form of RBE oil.
Methods: Twelve healthy volunteers (6 men and 6 women) orally ingested RBE oil (2 g) or RBE-enriched porridge (35 g, including 2-g RBE) with water or with milk, in a three-armed, crossover trial. Blood and urine samples were collected at baseline and up to 24 h after intake. Vitamin E (α-, β-, γ-, and δ-tocopherols and tocotrienols), ferulic acid (FA), and γ-oryzanol (ORY) were quantified by HPLC.
Results: The ingestion of RBE-fortified oatmeal porridge and RBE oil significantly increased FA concentrations in plasma, showing faster absorption and higher maximum plasma concentrations after the intake of the porridges, irrespective of the addition of water or milk. At least part of the FA could have been hydrolyzed from ORY. However, plasma vitamin E concentrations did not increase from baseline, and no intact FA esters (cycloartenyl ferulate, 24-methylenecycloartanyl ferulate, campesteryl ferulate, and β-sitosteryl ferulate) were detected in plasma or urine with any of the meal treatments.
Conclusions: Rice bran extract-enriched porridge and, to a lesser extent, RBE oil, provide relevant sources of bioaccessible and bioavailable ferulic acid, and could be further developed into functional foods with health potential.
Keywords: Ferulic acid; Gamma-oryzanol; Human study; Pharmacokinetics; Vitamin E.