Imagine that you've become very, very small and you're entombed within your gut. You look around you and notice that you are not alone. There are trillions of other very small creatures in here with you. All of these bacteria, viruses and fungi are busy doing very simple tasks. First, they're trying to stay alive as they battle each other for dominance. Second, they're trying to win this continuing battle by replicating themselves as much as possible. In order to do so they require the food that is regularly provided by each meal consumed. Whoever eats more also produces more offspring and wins the battle of survival; this war is waged continuously every day.
Scientists are beginning to understand how a shift in the mixture of these bugs can lead to poor health, including heart disease, inflammatory bowel diseases, high cholesterol, obesity and cancer. The balance of gut bacteria is also thought to influence behavior and the presence of certain mental disorders, such as depression. How does this happen? How can the bugs in your gut convince your brain that you should feel happiness or sadness and anxiety?
A recent study suggests that the answer is related to the mechanism by which alcohol acts in your brain to produce the same types of feelings. According to scientists at McMaster University in Canada and the University of Cork in Ireland [published in the Proceedings of the National Academy of Sciences] the specific mechanism involves a protein that responds to the presence of alcohol in the brain; this protein is called the GABA receptor. The bugs in your gut communicate with your brain via the GABA receptor. I would like to think that the little bugs are telling your brain "thank you" for that last tasty meal.