Bioavailability and pharmacokinetics of whole grain phytochemicals in overweight/obese adults

Abstract

Whole grains contain micronutrients and phytochemicals as well as fiber. While research suggests that fiber is a major contributor to the health benefits associated with whole grain consumption, other ingredients concentrated in the outer bran layer, e.g., alkylresorcinols, lignans, phenolic acids, phytosterols, and tocols, may also play an important role. To determine the acute bioavailability and pharmacokinetics of the major phytochemicals found in barley and oats, we conducted a randomized, 3‐way crossover trial in 13 healthy subjects, age 40–70 y with BMI 27–35.9. After a 2‐d run‐in period following a diet low in phytochemicals, subjects were randomized to receive muffins made with either 48 g whole oat flour, whole barley flour, or refined wheat flour + fiber (control), with a 1 wk washout period between each intervention. Blood and urine samples were collected at specified time points before and for 24 h following the consumption of each test food. Preliminary results (n=6) indicate the rank order for maximal plasma concentration (Cmax) of ferulic acid, the predominant phenolic acid, was oats>barley>control and time to reach Cmax (Tmax) was 3.6–4.3 h. Minimal changes in plasma phytosterols and tocols were observed, likely due to their low content in these flours. These data suggest that barley and oat phytochemicals are bioavailable. (Supported by USDA and Kellogg Co.).