Topical Area: Dietary Bioactive Components
Soybean fiber (SBF) is an insoluble, but highly fermentable dietary fiber. Previous in vitro fermentation studies with human feces have shown that SBF produces 1.5 – 8 times more acetate, propionate, and butyrate than oat bran, corn bran, or wheat bran fiber. Short chain fatty acids (SCFA) have been reported to play a key role in maintaining colon health and reducing inflammation. The impact of dietary SBF on colonic inflammation has not previously been examined. Our objective was to determine the anti-inflammatory efficacy of dietary supplementation with SBF in a mouse model of acute colonic inflammation.
Male C57BL/6J mice (5 weeks old) were randomized to AIN93G diet (CTL) or diet where 40% of the fiber was replaced with SBF (SBF-Hi). After 2 weeks of pretreatment, mice were given 2% dextran sulfate sodium (DSS) as the sole source of drinking fluid for 1 week to induce colonic inflammation. During DSS treatment, mice were maintained on their diet treatments. After DSS treatment, mice were euthanized and colonic inflammation was assessed.
DSS-treated mice had significantly larger spleens and shorter colons than mice treated with water. SBF-Hi mitigated DSS-induced increases in spleen weight (20% lower) and colon shortening (15% longer). Quantitative, reverse transcriptase PCR analysis showed that DSS-treatment increased colonic mRNA expression of interleukin-6 (Il6) and tumor necrosis factor-a (Tnfa) by 3-fold compared to water-treated mice. Dietary supplementation with SBF blunted these increases in Il6 and Tnfa by 87% and 71%, respectively.
Our results suggest that dietary supplementation with SBF may be a useful approach to mitigate colonic inflammation. On-going studies are focused on determining fecal levels of SCFA and measuring protein markers of inflammation and gut barrier function. Future studies are needed to evaluate whether the protective effects observed in this study are maintained in situations of more chronic colonic inflammation.
Funding Sources :
This work was funded by a grant from the Pennsylvania Soybean Board and by USDA National Institute of Food and Agriculture Appropriations under Project PEN04565.