Health‐promoting effects of dietary polysaccharide extracted from Dendrobium aphyllum on mice colon, including microbiota and immune modulation

Summary The health‐promoting effects of a polysaccharide ( DAP ) purified from Dendrobium aphyllum , on mice colon were investigated. The results indicated that consumption of DAP facilitated the differentiation degree of CD 4 + T cells to Th 1 , Th 17 and Treg cells; and depressed the differentiation degree to Th 2 cells, since DAP up‐regulated IL ‐6 expression (from 1.08 ± 0.24 to 3.40 ± 0.36). Besides, oral administration of DAP reduced the gastrointestinal transit time from 255 ± 1.21 to 164 ± 0.46 min, decreased the pH from 6.70 ± 0.27 to 5.54 ± 0.31, improved faecal water‐binding capability from 59.4% ± 0.35 to 63.5% ± 0.22. Additionally, the increase in four health‐promoting short chain fatty acids were observed, which might result from the enrichment of the relative abundance of health‐promoting microbiota genera, including Porphyromonadaceae and Ruminococcaceae . The DAP ‐induced up‐regulation of the genus Erysipelotrichaceae might be related to the homeostasis in both Th 1 /Th 2 and Treg/Th 17 .