Barb Goodman, PhD

If you’ve ever been told to eat yogurt or drink buttermilk after taking antibiotics for a bacterial infection, the suggestion might not make sense. The reason for consuming yogurt or buttermilk is to replenish the body’s bacteria that were killed by the antibiotics. But why would we intentionally introduce bacteria after we got sick from them in the first place? Short answer: Not all bacteria are created equal. While some bacteria do cause illnesses, not all are bad. In fact, many—like the ones in the gut—are good for us and play a role in the body’s normal physiology.

Gut microbes (bacteria), also known as the gut microbiota or microbiome, help the digestive tract work properly by breaking down food that did not get broken down earlier in the digestion process. They also help the gut perform other functions.

A recent article in the journal Cell described how gut bacteria is involved in making an important chemical called monoamine serotonin, also known as 5-hydroxytryptamine (5-HT). 5-HT, which is produced in the gut, has been shown to be important in regulating many bodily processes, such as digestive system movement and secretion, immune responses, blood clotting, and even bone and heart functions.  Abnormal levels of 5-HT have also been linked to diseases like irritable bowel syndrome, heart disease and osteoporosis. The new study showed that specific bacteria in the normal gut microbiome encouraged specialized cells in the lining of the colon (large intestine) to produce more 5-HT, which then enhanced the bodily functions that 5-HT influenced.

So, not only do the good bacteria tell the human cells what to do, they also help regulate the digestive system and other parts of the body including the blood, the heart and the bone.  That makes the good germs in the digestive system important for maintaining a healthy body. So, yogurt with active cultures—here we come!

Barbara E. Goodman, PhD, FAPS, is a professor of physiology at the University of South Dakota.