Dietary effect of guar gum and its partially hydrolyzed product on the lipid metabolism and immune function of Sprague-Dawley rats

The dietary effect of the water-soluble dietary fibers (WSDF), guar gum, pa rtially hydrolyzed guar gum (PHGG), glucomannan, highly methoxylated (HM) p ectin, on the serum lipid level and immunoglobulin (Ig) production of Sprag ue-Dawley rats was compared with that of water-insoluble cellulose. Althoug h serum total cholesterol and triglyceride levels were significantly lower in the rats fed with WSDF than in those fed with cellulose, a decrease in t he level of phospholipids was only observed in the rats that had been fed o n guar gum or glucomannan. In addition, all WSDP feeding enhanced IgA produ ctivity in the spleen and mesenteric lymph node lymphocytes, although the i ncrease in serum IgA level was only observed in the rats fed on WSDF, and n ot on PHGG. When mesenteric lymph node lymphocytes were cultured in the pre sence of various concentrations of guar gum or glucomannan, no significant increase in Ig production was apparent. These data suggest that WSDF indire ctly enhanced the Ig production of lymphocytes, and that serum lipid reduct ion and IgA production-enhancing activities of WSDF were dependent on their molecular sizes.