How does fiber improve our immunity? This is all related to the fermentation of fiber. When the fiber reaches the colon, friendly bacteria ferments the fiber and produce weak acid. The acidic colon is not friendly to harmful bacteria (see Figure 7). Therefore, it reduces the colonization of harmful bacteria in the intestinal tract. In addition, the short-chain fatty acids produced during the fiber fermentation process posses anti-inflammatory effects that further improve the body's immunity. The fermentation process also generates vitamin B and K. Vitamin B helps protect nerves and ensures that we can effectively use the body's energy. Vitamin K regulates blood clotting. Although fermentation produces gas and flatulence, over time, the intestines will adapt to a high-fiber diet and flatulence will decrease.