Polyphenol- and Glucuronoxylan-Rich Fiber Extract from Birch (Betula sp.) Wood Regulates Colonic Barrier Function and Cell Proliferation in Healthy Rats

Birch
wood-derived fiber extracts containing glucuronoxylans (GX)
and polyphenols show potential for various food technological applications.
This study investigated the effect of two extracts, GXpoly and pureGX,
differing in lignin content on colonic barrier function. Healthy rats
were fed diets containing 10% GXpoly, pureGX, or cellulose for 4 weeks.
Colon crypt depth was lower in the GX groups than in the control group,
but in the proximal colon, the result was significant only in GXpoly.
An artificial intelligence approach was established to measure the
mucus content and goblet cells. In the distal colon, their amounts
were higher in the control group than in the GX groups. All diets
had a similar effect on the expression of the tight junction proteins
occludin, claudin-1, and claudin-7. GXpoly enhanced the fecal IgA
production. Our results suggest that GX-rich extracts could support
the colonic barrier and work as functional food ingredients in the
future.