Effect of chitooligosaccharides on human gut microbiota and antiglycation.

•The biofunctionality of COS was associated with the modification of gut microbiota.•Prebiotic effect of COS was related to an increase in Bacteroides and Faecalibacterium, and a decrease in Klebsiella.•The increased acetic acid production by COS was positively correlated with Bacteroides abundance.•The antiglycation activity of COS and acetic acid was dose-dependent.•COS may prevent CML (a marker of AGEs) accumulation in adipose tissue.