ABSTRACT
CONTENTS Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143 Overview of the Immune System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144 Immunomodulatory Effects of Prebiotics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
Human Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146 Animal Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
Mechanisms for the Effects of Prebiotics on the Immune System . . . . . . . . . 153 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
Food and nutrients modulate immune functions in multiple ways. For essential nutrients, a number of studies have demonstrated amajor regulatory role within the immune system (Calder et al. 2002). The impact of nonessential food constituents on the immune system such as prebiotics and similar complex carbohydrates, however, has not been studied thoroughly (Schley and Field 2002, Watzl et al. 2005). For proper functioning of the immune system, the intestinal flora also plays an important role. Composition and metabolic activity of the intestinal flora are directly depending on dietary constituents including prebiotics. Prebiotics (for a definition see Chapter 1) occur in plant foodand isolatedprebiotics have recently becomea technical constituent of an increasingnumberof foods. Inulin (IN) andoligofructose (OF) are classifiedas prebiotics occurring as plant storage carbohydrates in vegetables, cereals, and fruits. Recent data indicate that prebiotics may modulate the gut-associated lymphoid tissue (GALT) as well as the systemic immune system.
