Methods for identifying a composition that neutralizes toxicity of a lipopolysaccharide are disclosed. The methods comprise comparing the amount of cytokine and/or prostaglandin E2 secreted by cells that have Toll-like receptors activated by a lipopolysaccharide in the presence or absence of a test composition. Methods of neutralizing toxicity of a lipopolysaccharide in an individual's oral cavity using compositions identified neutralizing toxicity of a lipopolysaccharide are also disclosed. Method of neutralizing toxicity of a lipopolysaccharide in an individual's oral cavity using oral care compositions that comprise combinations of zinc oxide and zinc citrate are also disclosed.