**8. Getting enough fiber diet and how it affects immunity**

The share of CD4+ and CD8+ T-cells in GALT, as well as their in vitro responsiveness to mitogens, were considerably affected by the diet's fiber intake. There was a bigger proportion of CD8+ T-cells in the IEL, lamina propria, and Peyer's patches after consuming the high fermentable fiber diet, as well as a higher proportion of CD4+ T-cells in the mesenteric lymph nodes and peripheral blood except for a higher CD4:CD8 ratio.

In the upper gastrointestinal system, prebiotic fiber is neither hydrolyzed nor absorbed, but instead assists as a selective substrate for one or a small number of beneficial colonic bacteria, modifying the gut microbiota. There is significant proof that prebiotic fibers (inulin and oligofructose) boost the percentage of good lactic acid bacteria in the human colon (**Figure 2**).
