Can intestinal bacteria influence mood?

Many of the bacteria which reside in the human gut, are beneficial, helping people with digestion and keeping the intestines in good working order. Scientists have reasoned this for some time. Now there is a body of evidence which suggests that bacteria dwelling in the gut can affect the brain, too, and thereby influence an individual’s mood and behaviour. The idea that gut-dwelling microbes can affect an animal’s state of mind may strike some people as outlandish. However, the new research is interesting. A recent paper on the topic was recently published in the Proceedings of the National Academy of Sciences. The study reports on results in mice where one group of mice were fed a certain type of bacterium. Using two groups of mice, the researchers found that levels of corticosterone, a stress hormone, were markedly lower in the bacteria-fed mice than they were in the control group when both groups were exposed to stressful situations. The key question which emerges from the research is whether a similar effect occurs in people. To find out more about this, see pharmaceutical microbiology.