Acute bioavailability and pharmacokinetics of avenanthramides (AV) from “false malted” oat bran high in endogenous AV

Abstract

Avenanthramides (AV), hydroxycinnamoyl alkaloids unique to oats, have antioxidant and anti‐inflammatory activities in vitro and in vivo. Concentrated AV mixtures extracted from oat are bioavailable in hamsters and humans. We examined the bioavailability of AV from the bran of oats subjected to “false malting,” a process that enriches the AV content of native kernels up to 40‐fold, in a placebo controlled, crossover study of 10 healthy adults (age 50–70 y, BMI 18.5–29.9). After a 2‐d run‐in period following a diet low in polyphenols and absent oats/oat products, subjects consumed either a muffin made with 20 g AV‐enriched oat bran (containing 45 mg AV) or a placebo muffin absent oats, with a 1 wk washout period. Blood samples were collected before and up to 24 h after consumption for determination of AV isomers, A, B, C, O, P, and Q. Following consumption of the AV‐enriched oat bran muffin, maximal plasma concentration (Cmax) was highest for AV‐O at 74.8±41.3 ng/mL and lowest for AV‐C at 2.9±1.8 ng/mL. Time to reach Cmax (Tmax) for all 6 AV ranged from 1.4±0.6 to 2.3±0.8 h. There was an apparent bimodal distribution for AV‐O, P, and Q. The second peak for each was nearly equal in concentration to their respective Cmax and appeared at ~4.0 h. No AV were detected following the placebo. These data indicate AV from this oat bran matrix are bioavailable in older adults. The bimodal pattern suggests reabsorption of some AV isomers through enterohepatic circulation. (Supported by USDA and AAFC)