Abstract
Dietary fibers exert various biological effects such as anti-cancer effect, improvement of serum lipid levels and intestinal flora, prevention of constipation, immunoregulatory activity etc. It has also been reported that water-soluble dietary fibers exert stronger immunoglobulin (Ig) production regulating activity than water-insoluble cellulose. Among them, oral administration of pectin, glucomannan, galactomannan or chitosan markedly enhanced serum IgA and IgG levels and decreased serum IgE level in Sprague-Dawley rats. They also enhanced IgA and IgG productivities of spleen and mesenteric lymph node (MLN) lymphocytes, as well as productivity of cytokines such as interferon-y and tumor necrosis factor-a of MLN lymphocytes. These results suggest that water-soluble dietary fibers regulate Ig production through the regulation of cytokine production. It has been shown that these dietary fibers and their sugar components could not stimulate Ig production of isolated lymphocytes directly . In addition, partially digested guar gum exerted weaker dietary effect on Ig production and lipid metabolism than intact guar gum. These results suggest that watersoluble dietary fibers exert their biological effects through the interaction with intestinal flora.
