The Brain in Your Gut
How we feel, whether we're depressed or happy, calm or anxious, may be influenced by external factors, but these emotions arise as a result of reactions occurring in the brain, right?
According to John Bienenstock, MD, of McMaster University, it's not quite that simple. The understanding that bacteria in your gut can affect your mind, "has just catapulted onto the scene," says Bienenstock (Monitor on Psychology, September 2012).
What is happening in our guts can influence neural development, brain chemistry, emotional behavior, pain perception and the response of the stress system. In animals, researchers have found that changes in bacteria can lead an animal to become either more bold or more anxious.
The Gut and How It Operates
The human gut, the only organ with it's own independent nervous system, has been referred to as the body's "second brain." This neural network in the gut can function even when the nerves that connect it to the brain have been severed.
From birth our guts develop bacteria that program the bodies immune system, block harmful microbes and regulate digestion and metabolism, allowing us to digest vitamins and nutrients from food. These bacteria also produce hundreds of neurochemicals that the brain uses to regulate physiological and mental processes. Learning, memory and mood are all tied to what happens in the gut. Ninety-five percent of the bodies serotonin, the neurochemical associated with positive mood, for example, is manufactured in the gut.
What This Means for You
The study of gut bacteria and its connection to how we think and feel is in the early stages. Most research has been conducted on animals and scientists are still trying to understand healthy gut bacteria.
However, scientists are finding observable effects of probiotics on the brain of healthy human volunteers. Researchers are also studying whether beneficial gut bacteria might mitigate the anxiety and depression that often accompany gastrointestinal disorders.
Our stress levels also appear to have an impact on the bacteria in the gut, making the interaction between gut and brain a two-way street. Higher stress levels appear to suppress beneficial bacteria. In animals, a stress induced overgrowth of harmful bacteria resulted in a greater susceptibility to infection, thus adding an additional stressor into the environment.
The connection between gut bacteria and symptoms of anxiety and depression is still not entirely clear. In the case of gut bacteria and our "second brain" the operative phrase should be "stay tuned." It's likely there is much more to come in the understanding of emotions and behaviors and their link to what is occurring in our guts.
We need to learn more! - Janet Singer - Sep 17th 2012
Very interesting article, and I look forward to more research regarding the connection between the gut and anxiety/depression. There's definitely something to this.....so many of those with OCD and other anxiety disorders have gastrointestinal issues also.