Konjac glucomannan ameliorated high fat‐induced oxidative stress in rats

Abstract

The aim of study was to determine ameliorative effects of konjac glucomannan (KGM), a viscous dietary fiber, on oxidative stress in Sprague‐Dawley rats fed a high‐fat fiber‐free diet. Six‐week‐old rats (n=8/group) were fed a normal‐fat (5% corn oil, w/w) fiber‐free, or high‐fat (25%, w/w) diets containing no fiber, KGM (5%, w/w) or inulin (5%, w/w, as a prebiotic control) for 4 weeks. The DNA damage of lymphocytes was determined by comet assay. In addition, lymphocytes were treated with formamidopyrimidine DNA‐glycosylase (FPG, 1 μg/mL) to determine its ability to defend oxidative stress. Plasma antioxidants and the malondialdehyde (MDA) levels in the plasma, liver and colon were also determined. Results indicated that the high‐fat fiber‐free diet significantly elevated lymphocyte DNA damage and MDA levels in the liver and colon, with a decrease in the plasma α‐tocopherol levels, as compared with its low‐fat counterpart. Incorporation of either KGM or inulin into the high‐fat fiber‐free diet significantly reduced the lymphocytes DNA damage and FPG‐induced lesion, and liver MDA levels. Furthermore, KGM and inulin significantly reduced the MDA level in the distal and proximal colon, respectively. Therefore, the present study suggests that KGM reduced oxidative stress caused by high‐fat diet in rats. This study was supported by the National Science Council Grant NSC‐99‐2320‐B‐040‐014‐MY2, Taipei, Taiwan.