LPS (lipopolysaccharide) is a substance that exists on the outer membranes of some forms of bad bacteria. LPS protects bad bacteria in the digestive system (the gut) from being digested and thus destroyed. Although beneficial to bad bacteria, LPS is known as an endotoxin which is a toxic substance that is made by the bacteria itself. When LPS makes itself into the bloodstream of animals as shown in lab tests, it brings about severe inflammation in the body. LPS may be linked to autoimmune diseases like Rheumatoid arthritis and MS (Multiple Sclerosis).