**1. Introduction**

In addition to maintaining human growth, fertility, and health, the diet is also essential to modulating and supporting the symbiotic microbiota and the microbial communities that inhabit the digestive tract. Our gut harbors trillions of microbes that play a significant role in datary fiber metabolism. The gut microbiome modulates maturation of the immune system [1], glucose and lipid metabolism [2], and juvenile growth [3]. The microbial diversity in the gut depends on the intake of dietary fibers [4] and any alteration of dietary intake of fibres may result in dysfunction of the gut and the development of chronic inflammatory diseases like intestinal bowel disease (IBD), autoimmune diseases, colorectal cancer (CRC), and allergies. The gut microbiome is affected by diet, which in turn affects the immune system. We wondered whether the results of the high-fiber diet intervention may have coincidentally impacted participants' immune systems because the microbiota of the group differed. Here we will discuss how dietary fiber impacts gut microbial ecology, host physiology, and health by specifically focusing on the molecular impact of dietary fiber metabolites on intestinal immunity

Here, we specifically discuss the effects of the gut microbiota on immunometabolism, and more precisely, on the intracellular metabolism of immune cells, in health and the potential consequences in diseases. In this chapter, emphasis is placed on the effects of dietary fiber metabolites as prime signaling molecules, through different signaling pathways and their link between gut microbiota and host health.
