The trillions of microbes that inhabit the human intestine, known collectively as the gut microbiota, play critical roles in health. Research demonstrates that the microbiota provides protection against infections by preventing pathogenic colonization in the gut. Findings from a new study indicate that taurine facilitates the gut microbiota’s immune response to infection.

Maintaining a “friendly” population of gut microbes is essential for good health. An imbalance in the number of harmful versus helpful microbes, a condition known as dysbiosis, drives many disease states, including cardiovascular disease, allergies, asthma, and obesity.

Taurine is an amino acid produced in the body and present in many foods. It plays roles in fat metabolism and many other physiological processes. Taurine breaks down to form hydrogen sulfide, a gas that promotes cardiovascular health and may be useful in treating Alzheimer’s disease. Low taurine levels promote pathogenic colonization of the human gut, but high levels help resist it.

The authors of the study used two groups of mice (normal and germ-free) to better understand how the microbiota influences resistance to colonization. They subjected the normal mice to a mild infection. After the mice recovered, the investigators transferred bacteria from the guts of the recovered mice to the germ-free mice and infected both groups of mice again. They found that the first mild infection primed the gut microbiota to resist colonization associated with a second infection.

Next, they gave the mice either taurine or bismuth subsalicylate (the primary ingredient in many antidiarrheal medicines) in their drinking water for two to three weeks. They subjected the mice to another infection and again measured the response. They found that taurine improved the microbial resistance to pathogenic colonization, but bismuth subsalicylate diminished it due to its capacity to inhibit hydrogen sulfide production.

• Link to study abstract.