'Good' Bacteria In Digestive Tract Appear To Boost Immunity

According to a new study, the beneficial bacteria found in the human gut not only help ensure proper digestion but also strengthen the immune system against the parasite Toxoplasma gondii.

The microorganism is responsible for toxoplasmosis, a disease that mostly affects cats but can also be transferred to humans. Although the infection is typically mild, it can be dangerous for those with a weakened immune system, or for pregnant women and their fetuses.

Scientists from the University of Texas Southwestern Medical Center found that the presence of T. gondii stimulates the good bacteria to send activating signals to a type of immune protein that produces an inflammatory response against the pathogen.

Dr. Felix Yarovinsky, assistant professor of immunology at UT Southwestern and senior author of the study, says researchers suspect that because the bacteria co-evolved with their human hosts, they must have found a way to induce the sufficient stimulatory effects of the immune system without causing illness or death.

"The fact that commensal bacteria vary dramatically from person to person might explain why therapeutic outcomes vary so much," he adds.

People who are concerned about digestive health and immunity may enhance their diet with supplements containing probiotics.