Research advances on whole grains benefit on metabolic syndrome via gut homeostasis regulation

Whole grains are abundant in polyphenols, phytosterols, dietary fiber β-glucan carotenoids, etc. They are highly bioavailable as intermediate metabolites processed by gut microbiota. These intermediate metabolites can enter the circulation from the gut, and then participate in the biochemical pathways that induce metabolic syndrome and improve the abnormal state of body. Metabolic syndrome is often accompanied by oxidative stress, carbonyl stress, inflammation and other abnormal states. Intermediate metabolites such as polyphenols can signal the brain. Then, under the control of the brain, it regulates the blood sugar level, blood lipid level, bile acid level, etc., and maintains the health. In this process, the brain-gut axis and liver-gut axis play a crucial part. In this review, the pathogenesis of type 2 diabetes (T2DM) mellitus, obesity, atherosclerosis and nonalcoholic liver syndrome and the role of brain-gut axis and liver-gut axis in the pathogenesis of metabolic syndrome were described in detail. The regulatory role of whole grains in these four metabolic syndromes was investigated. Dietary components have great potential for better utilization in the prevention and treatment of metabolic syndrome. The importance of a whole grain diet was explored and techniques for improving the bioavailability of functional components in whole grains were also investigated.