**7. Prebiotics, probiotics and diet**

Prebiotics are food ingredients that are non-digestible but fermentable oligosaccharides. The primary role of prebiotics in food is to stimulate the fermenting activity of gut microbes and eventually trigger the growth of beneficial gut microbes [182–185]. Probiotics on the other hand are special foods that contain a certain amount of alive non-pathogenic bacteria which help to improve gut health and confer eubiosis [186, 187]. Bifidobacteria, lactobacilli streptococci and *E. coli* are the main bacterial strains that constitute most of the available probiotics. Prebiotics and probiotics supplementation has been shown to reduce inflammation and obesity in T2D patients [188–192]. The beneficial effect of prebiotics and probiotics on gut health, in general, is well accepted. However, the expected benefits of pre and probiotics in dysbiotic T2D patients is limited. Advanced stage or elderly diabetic patients fails to respond to pre and probiotic supplementation as compared to young and early-stage T2D patients [190, 193, 194]. An appropriate ratio of different gut microbes is extremely important for proper metabolic physiology. As dysbiosis has been attributed as an important permissive or causative factor in developing T2D. Extensive use of high-fat diets, diets which are also called western diets or fast food, have the ability to modulate gut microbiota. Specifically, the downregulation of beneficial Bifidobacteria

### *DOI: http://dx.doi.org/10.5772/intechopen.105616 Gut Microbiota Potential in Type 2 Diabetes*

(Actinobacteria), which helps to break down food, and nutrient absorption and helps to alleviate constipation and diarrhea by fighting off pathogenic microbes. As Actinobacteria only makes up to 3% of the total gut microbiota, the high fat dietinduced decrease in Bifidobacteria causes an acute pathological impact on metabolism and gut health. A high-fat diet also induces an unwanted increase in the proteobacteria, which usually accounts for a maximum 8%. An increase in the LPS containing proteobacteria causes inflammation and obesity, a condition known as endotoxemia which is accompanied by insulin resistance. Oligofructose-containing prebiotics has been shown to lower LPS containing Proteobacteria by enhancing Bifidobacterial thus modulating endotoxemia and via GLP-1 dependent pathway improves glucose tolerance [195]. Prebiotics, probiotics and fecal microbial transplantation (FMTs) are the main treatment options to enhance gut microbiota. The limited success of these treatment options to restore and maintain the eubiosis over time and the unique microbiology of the gut microbiome has called for a better understanding of gut microbial response and adaptation to different diets and lifestyles. An elegant recent report documenting the *in vivo* bacterial gene expression profile in the gut in different groups of mice indicates that bacterial gene expression is hugely impacted by the type of food present in the gut [196]. Lifestyles, cultures and specific diets have been shown to modulate the gut microbiome in healthy non-diabetic subjects (**Figure 1**). These are lifestyle/diet-induced effects that eventually cause metabolic disorders and obesity. Apart from these detrimental outcomes of certain lifestyles, medications especially antibiotics can severely damage the overall population and the specific ratio of the gut microbiome.

#### **Figure 1.**

*Impact of the use of probiotics and prebiotics on the gut microbiome in terms of its functionality and improving the glycemic control through manipulation of multiple factors like improved incretin secretions, increase in the production of SCFAs, improved bile acid metabolism and the decrease in the LPs induced low grade inflammatory response.*
