Global, distinctive, and personal changes in molecular and microbial profiles by specific fibers in humans

Dietary fibers act through the microbiome to improve cardiovascular health and prevent metabolic disorders and cancer. To understand the health benefits of dietary fiber supplementation, we investigated two popular purified fibers, arabinoxylan (AX) and long-chain inulin (LCI), and a mixture of five fibers. We present multiomic signatures of metabolomics, lipidomics, proteomics, metagenomics, a cytokine panel, and clinical measurements on healthy and insulin-resistant participants. Each fiber is associated with fiber-dependent biochemical and microbial responses. AX consumption associates with a significant reduction in LDL and an increase in bile acids, contributing to its observed cholesterol reduction. LCI is associated with an increase in Bifidobacterium. However, at the highest LCI dose, there is increased inflammation and elevation in the liver enzyme alanine aminotransferase. This study yields insights into the effects of fiber supplementation and the mechanisms behind fiber-induced cholesterol reduction, and it shows effects of individual, purified fibers on the microbiome. [Display omitted] •Cross-over clinical trial examines how highly purified fibers select a specific microbiome•Arabinoxylan decreases cholesterol in part through increased bile acid synthesis•Cholesterol responders ate more protein and had higher levels of feruloyl esterase•High doses of inulin cause inflammation and elevation of alanine aminotransferase (ALT) Lancaster et al. directly test the effects of two highly purified fibers on extensive clinical and biochemical profiles. They found that arabinoxylan, a common fiber of Metamucil, reduced cholesterol through bile acid production, whereas inulin, a common fiber of many vegetables, had no effect, although high doses caused inflammation.