Significance of Inulin Fructans in the Human Diet

This paper reviews the physicochemical properties and nutritional significance of inulin fructans (oligofructose and inulin). These compounds are naturally present in a large number of food crops and serve in our diet as dietary fiber. Inulin fructans can be isolated and purified from the chicory root and used as ingredients in a large range of foods to improve structure and/or taste and to increase the intake of dietary fiber. Inulin fructans have a low caloric value, are safe, and generally well tolerated up to a level of 20 g/d. They exert a range of effects, which can be differentiated into direct effects on the gut and the intestinal flora and indirect systemic effects. Direct effects on the gut include prebiotic (bifidogenic) effects, improvement of bowel habits and bowel function in constipated subjects, increased colonic absorption of minerals (Ca and Mg), and secretion of satiety hormones. Indirect effects are on blood lipids, bone mineral content, the immune system, and energy homeostasis. These issues are discussed and it is argued that promising avenues for research are particularly in the areas of energy homeostasis and systemic low-grade inflammation in relation to changes in the composition of the intestinal microbiota.