Nondigestible carbohydrates and mineral bioavailability

Generally, fiber and compounds associated with fiber in cereal products (e. g., phytates) have been found to reduce the apparent absorption of minerals (such as calcium, magnesium, zinc and manganese) in humans, livestock and animal models. The effects of "soluble" forms of fiber (specifically pectin s, gums, resistant starches, lactulose, oligofructose and inulin) on minera l absorption are more difficult to characterize. The addition of these solu ble forms of fiber has been found in various studies to add viscosity to th e gut contents, promote fermentation and the production of volatile fatty a cids in the cecum, have a trophic effect on the ceca of animals and increas e serum enteroglucagon concentrations, Thus it is not surprising that the a ddition of soluble forms of fiber to diets often has been found to improve absorption of minerals. This may reflect absorption of electrolytes from th e large intestine. Future work should address the mechanisms by which inges tion of nondigestible carbohydrates improves mineral absorption in humans.