Dietary iron is a crucial nutrient element for biological processes of both hosts and gut microbiota. Deficiency in dietary iron is a highly common disorder in the developing locations of the world and can be healed by oral iron administration or complementary iron diet. While the redundant iron that enters the gut lumen leads to negative effects, and modulates the gut microbial composition and function. Such modulation led to a significant effect on vital biological pathways of the host, including metabolic disease (obesity and type 2 diabetes), metabolites (SCFA, blood glucose and cholesterol), bile acid metabolism, endocrine, neural, and other well-being patterns. This review covers the multifaceted aspects of different nutritional iron stress on the composition and function of microbial gut in monogastrics and consequential health conditions as well as it reveals unclear points that need further studies.