# Botanicals in Functional Foods and Food Supplements: Tradition, Efficacy and Regulatory Aspects
## 4 Botanicals in Functional Foods
### Soluble and Insoluble Fibers
#### 4.1.2 Prebiotic Fibers  
The prebiotic fibers fall into the category of soluble fibers. The definition of the term \"prebiotic\" has undergone a certain number of changes since the 1990s, a period in which they were identified as beneficial ingredients of the human diet. In agreement with the International Scientific Association for Prebiotics and Probiotics, a prebiotic fiber is \"a substrate, that is selectively used by host microorganisms conferring a health benefit\" [15]. Similarly, the Food and Agriculture Organization of the United Nations (FAO) published the following definition in 2008: \"a nonviable food component that confers a health benefit on the host associated with modulation of the microbiota\" [16].  
In recent decades, the awareness of the critical role played by the intestinal microbiota on human health has progressively grown. Studies to support this knowledge have stimulated the formulation of food products capable to contribute to the modulation of microbiota towards positive bacterial strains (mainly lactic bacteria) at the expense of pathogenic ones. These foods, mostly milk-based, contain particular strains of live bacteria (probiotics) or soluble fibers capable of promoting their growth. In functional foods, the most commonly used prebiotic fibers are: inulin, fruct-oligosaccharides (FOS) and galacto-oligosaccharides (GOS); the latter are mostly included in products for infants. Inulin is a linear polymer of 2-60 fructose molecules linked by \(\beta\)-(2-1)-bonds.  
The nature of chemical bonds prevents inulin from the usual digestion of caloric sugars. FOS are similar to inulin for chemical bonds, but the number of units ranges between 2 and 10 [17]. Inulin and FOS are storage carbohydrates contained in several plants; the most important sources are chicory, sugar beet, leeks, asparagus, and Jerusalem artichokes. Inulin and FOS reach the colon undigested where they are fermented by the \"positive\" microbiota. A health claim for \"native chicory inulin\" is allowed in EU; it states that \"chicory inulin contributes to normal bowel function by increasing stool frequency\". This claim must be associated with those products, providing at least a daily intake of 12 gof inulin, as a non-fractionated mixture of monosaccharides (<10%), disaccharide, inulin-type fructans and inulin, with an average of polymerization \(\geq 9\) (see Table 1).  
Although from animal origin, galacto-oligosaccharides (GOS) are considered here to describe the possible healthy effect due to prebiotic fiber. GOS are oligosaccharides containing 2-10 molecules of galactose and one molecule of glucose. The purity and degree of polymerization largely influence the prebiotic properties of these oligosaccharides, as shown in clinical studies [18; 19]. GOS are widely used in lactating formulas to improve the microbiota colonization and modulate the intestinal disorders such as colic. The effects of GOS added to infant formulas were evaluated in a randomized, double-blind, controlled, parallel-group clinical trial including healthy term infants [20]. Three groups were considered: breastfed, formula-fed, and GOS-supplemented formula-fed infants. The effects of supplemented formula were assessed considering four bacterial targets: _Bifidobacterium_, _Lactobacillus_, _Clostridium_, and _Escherichia coli_. The effect of the prebiotic-supplemented formula was very close to that of breast-feeding in stimulating _Bifidobacterium_ and _Lactobacillus_ growth and in inhibiting _Clostridium_ growth. The whole result was a significantly lower incidence of colic [20].