Bioactive Dietary Fibers Selectively Promote Gut Microbiota to Exert Antidiabetic Effects

High
intake of dietary fibers was found to be inversely associated
with type-2 diabetes (T2D), whereas the difference among different
dietary fibers on T2D remains unclear. Therefore, we have investigated
the effects of different dietary fibers on T2D. Nine types of dietary
fibers were used to investigate and evaluate their effects on type-2
diabetic rats via physiology, genomics, and metabolomics. We found
that supplementation with β-glucan, arabinogalactan, guar gum,
apple pectin, glucomannan, and arabinoxylan significantly reduced
the fasting blood glucose, whereas carrageenan, xylan, and xanthan
gum did not affect glycemic control in diabetic rats. Also, bioactive
dietary fibers (β-glucan, arabinogalactan, guar gum, and apple
pectin) associated with the increased butyric acid level and abundance
of beneficial bacteria (Lachnobacterium, Parabacteroides, Faecalibacterium, Akkermansia, and some butyric acid-producing bacteria), as well as improved
host metabolism by decreasing 12α-hydroxylated bile acids, acylcarnitines,
and amino acids (leucine, phenylalanine, citrulline, etc.), thereby
exert beneficial effects on T2D. It was also found that β-glucan
might attenuate insulin resistance via downregulation of Prevotella copri-mediated biosynthesis of branched-chain
amino acids in T2D. Together, our study uncovered the effects of different
dietary fibers on T2D, along with their potential mechanism.