The Bioavailability and Metabolism of Phenolics, a Class of Antioxidants Found in Grains
Consumption of whole grains has been shown to reduce the risk of chronic diseases. Whole grains contain a variety of bioactive compounds with antioxidant properties that can help prevent disease by inhibiting oxidative damage. The health benefits of whole grains depend not only on the functions of the bioactive compounds they contain, but also on the quantities of those compounds consumed, their metabolism, their bioavailability in different tissues, and the functions of their metabolites in the body. This article provides an overview of grain antioxidants, including their metabolism and bioavailability, with a focus on the phenolics ferulic acid, alk(en)ylresorcinols, and avenanthramides. Ferulic acid is the most abundant form of phenolic acid found in cereal grains; alk(en)ylresorcinols are found in large quantities in rye and wheat; and avenanthramides are found only in oats. Results from in vitro, in vivo, and human studies indicate that all three phenolic compounds have potent antioxidant properties that could significantly contribute to the ability of whole grains to prevent certain chronic diseases. However, the low bioavailability of these phenolics, as measured in human studies, is a concern for health applications.