The authors explore the basic biology of LPSs and its interaction with the host receptor complex, comprising Toll-like receptor 4 and co-receptors, as well as the concept of endotoxemia as a mediator linking periodontitis to an increased risk of conditions such as cardiovascular disease, obesity, insulin resistance, type 2 diabetes, non-alcoholic fatty liver disease, metabolic syndrome, and dyslipidemia. This evidence concerns the gene TLR4 and metabolic syndrome.