Emerging science on benefits of whole grain oat and barley and their soluble dietary fibers for heart health, glycemic response, and gut microbiota

The aim of this work is to review the major mechanisms by which consumption of whole grain oats and barley, and beta-glucans, reduces the risk of coronary heart disease, type 2 diabetes, and other noncommunicable chronic conditions. These effects have been predominantly explained by the role of soluble dietary fibers and smaller bioactive compounds, such as phenolic compounds, in oats and barley. These help to reduce the level of serum low-density lipoprotein cholesterol, decreasing postprandial blood glucose and modulating gut microbiota. In the present review, the role of viscosity development of the intestinal content by beta-glucans in these mechanisms is discussed, as well as the impact of processing conditions altering the composition or the physicochemical characteristics of beta-glucans.