Bad Mood? Maybe It's Your Gut Microbiome's Fault

Good mood or bad, maybe your gut microbiome is at least partially to blame. Even xkcd has gone there!

This week the New York Times had a great article about the relationship between your gut and your brain. The microbes that live in your gut might be doing more than just digesting certain foods, producing vitamins like B and K, maintaining balance with other microbes and playing a role in your immune system. They also are making neurochemicals, some of which are the same ones our bodies produce: dopamine, serotonin and gamma-Aminobutyric acid (GABA). These molecules affect mood, depression and anxiety. And since it is known that a large percentage of these neurochemicals originate in the gut it makes sense that some of them come from our microbes. This has implications in potentially treating anxiety and depression and even autism and hyperactivity.

The article focuses on the research of Dr. Mark Lyte, now at the Iowa State College of Veterinary Medicine, where he has been studying this interaction between the gut and brain for many years. He has looked at the role of stress on microbiota such as adding a stress hormone, norepinephrine, to bacterial cultures and observing their response (the bacteria grew much more than controls) and at how stressful conditions imposed on cattle worsen their infections with pathogenic bacteria. He also has looked at the effects of bacteria on anxiety.

Also mentioned in the article is Dr. Michael Fischbach from UCSF, who looks at naturally occurring molecules and antibiotics produced by microbes within and on us. I had the pleasure of seeing his memorable talk at this year’s AGBT and it was a highlight of the conference for me. He talked about how the gene clusters involved in producing these naturally occurring molecules are not transcribed in culture – yet they are heavily transcribed in their natural environment, such as in your gut. This makes them more difficult to study in the lab but makes this field of microbiome research even more fascinating.

One last thing to mention is a study where a team led by Dr. John Cryan at University College Cork fed mice a common bacteria found in yogurt and probiotics, Lactobacillus rhamnosus. Lactobacilli are known to release large amounts of GABA, which calms nervous activity. They found that mice who were fed Lactobacillus were more relaxed and less anxious than the mice who were not fed it.

Even though the researchers say that it is too early to run out and buy probiotics to self-adjust your gut microbiome and attempt to alter your mood – a cup of yogurt is sounding really good right now!