Dietary Fiber and Short-Chain Fatty Acids
High levels of dietary fiber have been shown to decrease the relative risk for Crohn's disease. In a trinitrobenzenesulfonic acid model of colitis, dietary fiber was shown to decrease the production of TNF-alpha and nitric oxide (known mediators of inflammation). It was also noted that there was a higher concentration of short-chain fatty acids, which Rodriguez-Cabezas and colleagues conclude may play a role in both decreasing the production of the certain inflammatory mediators and also contribute to the repair and regeneration of the damaged colonic cells. Butyrate and other short-chain fatty acids such as acetate, propionate, and valerate are created when soluble fibers are fermented in the intestine. Some believe that the production of the short-chain fatty acids, which are decreased in colitis, is important to maintain microbial balance and prevent dysbiosis.
Butyrate is believed to exert anti-inflammatory effects by decreasing the production of cytokines thought to up-regulate inflammation, such as IL-6 and IL-8. Additionally, colonic cells use these short-chain fatty acids (such as butyrate) as their main source of oxidative fuels. Although butyrate administration does result in improvement, the studies done on butyrate in ulcerative colitis are conflicting as to the statistical significance of improvement.
A recent randomized controlled trial comparing Plantago ovata seeds (a form of dietary fiber whose fermentation in the colon results in the production of butryrate) to oral mesalamine demonstrated equal effectiveness in the maintenance of remission in patients with ulcerative colitis. Two open-labeled trials (one at 4 weeks and the other at 6 months) have demonstrated clinical improvement in patients with ulcerative colitis via the administration of germinated barley foodstuff. Germinated barley foodstuff is believed to exert its influence by increasing butyrate production, and possibly encouraging the growth of beneficial bacteria, including Bifidobacterium and Eubacterium limosum (believed to produce butyrate).[50,51]
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Cite this: Dietary Factors in the Modulation of Inflammatory Bowel Disease Activity - Medscape - Mar 27, 2007.