The Role of Beneficial Bacteria in Mental Health

March 19, 2015 Updated: March 19, 2015

More and more research is focusing on the role of beneficial bacteria in the intestinal tract and mental health.  Beneficial bacteria help the body function in different ways, including our supporting our emotional well-being, in contrast to bad bacteria such as E.coli and Clostridium difficile, which can make us ill.

Traditionally, studies have focused on the role of beneficial bacteria in digestion and immune health.  Good bacteria digest and extract nutrients from the food we eat, and can synthesize certain nutrients, such as vitamin K and vitamin B12.  Vitamin K helps our blood to clot and plays a role in bone health while vitamin B12 is involved in energy production, nervous system functioning, and the formation of red blood cells. Good bacteria also line our gut to fight off pathogens and thus reduce our risk of illness. They actually secrete chemicals to fight off microbes entering our body.  Our gut truly has an intelligence of its own and has become known as our “second brain.”

More recent research on beneficial bacteria reports that certain strains produce chemicals associated with our mental health.  Bifidobacterium dentium, for example, secretes a neurotransmitter called GABA, which has a calming effect on our body.   When GABA levels are low, we become anxious.

Gut bacteria produce ninety-five percent of the serotonin in our body, a feel-good chemical that when depleted typically results in depression and anxiety.  Gut bacteria also produce half of our dopamine levels, a chemical that is related to functions such as movement control, the experience of pleasure and pain, memory, attention, sleep, mood, and learning.  Epinephrine and norepinephrine are released by gut bacteria and help the body react to emergency situations.

Treatment of mental health conditions is moving more toward using different strains of probiotic bacteria in treating conditions, such as anxiety and depression.  Anxiety and depression are believed to be associated with decreases or depletions of different strains of good bacteria in the intestines.  Studies are emerging showing improvements in mood and lessening of anxiety when probiotics are introduced into the diet. This is an emerging field, but one that holds promise for the future of mental health.  Researchers are focusing on specific strains and combinations of strains to manage our emotions.

Until treatment with specific strains of beneficial bacteria becomes more mainstream with further research, there are everyday steps that we can take to support a healthy gut and a general feeling of well-being.  One option is to take a high quality probiotic supplement daily with a variety of different strains of beneficial bacteria and at containing at least 10 to 20 CFUs of colony forming units.

Probiotics, which are live bacteria and yeasts, also are contained in specific foods, including sauerkraut, miso soup, soft cheese, kefir (a yogurt-like drink), sourdough bread, buttermilk, sour pickles, and tempeh (a type of fermented soy).  There also are foods that we can eat that probiotics feed on, including legumes, oatmeal, asparagus, Jerusalem artichoke, bananas, and red wine.

Adding probiotics to our diet has the added benefit of crowding out some of the bad bacteria in our gut and reducing the risks of illness.  Bad bacteria can overload our intestinal tract and lead to inflammation in the body, which in excess has been associated with such conditions with inflammatory bowel disease and rheumatoid arthritis.  Bonnie J. Kaplan et al in their article, The Emerging Field of Mental Health: Inflammation, the Microbiome, Oxidative Stress, and Mitochondrial Function (2015) report associations between inflammation in the body and emotional states, such as depression, bipolar disorder, and schizophrenia.  While only associations and not direct causes, current research is looking to see whether treating inflammation will help to ameliorate symptoms. 

Another tract to take for a healthy gut is to eat nutritionally, i.e. a diet relatively free of processed foods and trans-fats, and minimizing psychological stress. In terms of psychological stress, Bonnie J. Kaplan et al report studies showing that emotional stress early in life can contribute to symptoms of irritable bowel syndrome and psychiatric disorders in adulthood.  Overuse of anti-bacterial products and anti-biotics also can kill off good bacteria along with bad bacteria and should be considered when trying to maintain a healthy gut.

“Let food be thy medicine and medicine be thy food.” – Hippocrates