Konjac Glucomannan and Inulin Systematically Modulate Antioxidant Defense in Rats Fed a High-Fat Fiber-free Diet

Abstract

The aim of this study was to investigate the effects of konjac glucomannan (KGM) and inulin on the balance between pro-oxidative status and antioxidative defense systems in the colon, liver, and plasma of rats fed a high-fat fiber-free diet. Male Sprague-Dawley rats (n = 8 animals per group) were fed a high-fat (25% corn oil, w/w) fiber-free diet or that supplemented with KGM or inulin fiber (5%, w/w) for 4 weeks. The index of pro-oxidative status, malondialdehyde (MDA), and blood lymphocyte DNA damage; the antioxidative defense, that is, antioxidant enzymes (glutathione peroxidase, superoxide dismutase, catalase) in the colonic mucosa and liver; and the plasma antioxidant levels were determined. The fermentation of fiber was shown in fecal short-chain fatty acids. Incorporation of KGM and inulin into the high-fat fiber-free diet beneficially reduced the MDA levels of the colon and liver and DNA damage in blood lymphocytes. On the other hand, both fibers enhanced the antioxidative defense systems by up-regulating the gene expressions of glutathione peroxidase and catalase in the colonic mucosa and of superoxide dismutase and catalase in the liver. Furthermore, KGM and inulin promoted antioxidative status in the blood by elevating the α-tocopherol level. KGM and inulin were well-fermented in rats and increased the concentration and daily excretion of fecal short-chain fatty acids, especially acetate and butyrate. These results suggest that in vivo utilization of KGM and inulin stimulated both local and systemic antioxidative defense systems in rats.

In vitro fermentation of nuts results in the formation of butyrate and c9,t11 conjugated linoleic acid as chemopreventive metabolites

“…In addition, Erhardt et al [58] investigated the effect of different dietary compositions on the in vitro oxygen radical production in human feces and found that a diet rich in fiber diminishes the in vitro formation of reactive oxygen species in human feces and decreases MDA levels in plasma. Wu and Chen [59] have shown that the supplementation of inulin to a high-fat and fiber-free diet led to an increase in the antioxidant defense system by up-regulating gene expression of glutathione peroxidase and catalase in colon mucosa as well as a reduction in MDA levels in the colon of rats. In addition to the modulation of antioxidant enzymes in colonic mucosa cells, antioxidant and MDA-lowering effects of dietary fiber could be mediated by its prebiotic properties, i.e., promoting the growth of bifidobacteria and lactobacilli [7].…”

Intraperitoneal administration of butyrate prevents the severity of acetic acid colitis in rats

“…It does this partly by up-regulating the gene expressions of glutathione peroxidase and catalase. In addition, butyrate promotes antioxidative status in the blood by elevating the α-tocopherol level (Wu and Chen, 2011).…”

Daily Feeding of Fructooligosaccharide or Glucomannan Delays Onset of Senescence in SAMP8 Mice

“…Additionally, glucomannan (GM) is a soluble dietary fiber and nondigestible polysaccharide. Ingestion of GM stabilizes blood glucose concentrations and soluble dietary fiber is associated with decreased levels of oxidative stress [23]. Nondigestible saccharides, which escape the digestion by small intestinal enzymes, reach the large intestine and are fermented by intestinal microbes.…”