Can the Bacteria in Your Gut Affect Your Mood?
Historically there has been sparse research on the relationship of gut bacteria and the brain. That’s changing, and as the research grows so does public awareness.
Gut disorders have been linked to health problems beyond the gut, leading Hippocrates to declare some 2,000 years ago that “All disease begins in the gut.” This has proven to be prophetic and we now have the scientific tools to validate this assertion.
In the early 1900’s researchers discovered the gut has a mind of its own, the enteric nervous system (ENS). It is a rich network of neurons imbedded in the wall of the gut. This nervous system, sometimes called the “second brain” sends and receives signals, learns, remembers experiences and responds to emotions. The terms “gut instinct or gut feeling” lend credence to the experience of the ENS. The enteric nervous system can work with the brain or function independently from the brain coordinating the complex digestive process on its own. The two brains are so closely linked “The gut can upset the brain just as the brain can upset the gut”. Recent research on gut bacteria has brought added interest in the enteric nervous system and specifically how gut bacteria affects mood.
Inside the gut is a “parallel civilization” of around 6 pounds of bacteria, about 90% of the cells contained within the body. This mass of bacteria, called the microbiome, does much more than assist in digestion. It lines the surface of the gut and communicates with the body by producing many of the same messenger molecules as the brain. Through these chemical messengers, the microbiome communicates with the neurons in the gut wall (the “second brain”) which in turn passes information up the vagus nerve to the brain. The kind of neurotransmitters these bacteria produce can determine your mood. The gut bacteria produces more of the neurotransmitter Serotonin than the brain. It is known as the “feel good” chemical involved in preventing depression and aggression, along with regulating appetite, sleep and body temperature. Serotonin produced in the gut is also involved in repairing damaged cells in the liver and lung and helps the heart. Half of all the neurotransmitter Dopamine in the body is found in the gut. In the brain this neurotransmitter is associated with pleasure and the reward system, motivation. In the gut Dopamine is responsible for signaling the contraction of muscles of the gut.
So what does the gut tell the brain? In 2006 a research article in The British Journal of Psychiatry stated that stimulation of the vagus nerve is successful in the treatment of chronic depression. This gut-brain signaling could explain why certain foods make us feel good. A study published in The Journal of Clinical Investigation in 2011 found that fatty acids in the gut caused the brain to be less affected by pictures and music designed to cause sadness. In the same volume, another study found that mice exposed to chronic stress sought out fatty foods.
The take away from this blog is, evidence supports that the bacteria in your gut and the food you eat have an effect on your mood. So what can you do?
Caring for your gut may be your most powerful tool for brain health and happiness.