Believe it or not, tiny microbes lining your gut actually play a huge part in your mental and neurological health. A groundbreaking study performed by UCLA researchers shows the strong connection between healthy gut bacteria and brain functioning.

Regarding this study, Dr. Emeran Mayer, a professor of medicine (digestive diseases), physiology and psychiatry at the David Geffen School of Medicine at UCLA and the study’s senior author, stated:

“There are studies showing that what we eat can alter the composition and products of the gut flora — in particular, that people with high-vegetable, fiber-based diets have a different composition of their microbiota, or gut environment, than people who eat the more typical Western diet that is high in fat and carbohydrates,” Mayer said. “Now we know that this has an effect not only on the metabolism but also affects brain function.”

While scientists say they still need to do further research into how exactly this occurs, some believe that the gut microbiome release signaling molecules into our gut, affecting our dietary decisions. Since the gut is linked to the immune system, endocrine system, and nervous system, these signals consequently impact our physiological and behavioral reactions.

However, just as the bacteria can influence our behaviors, we can alter them by changing what we consume, which would then alter the bacteria itself.

Research proposes that gut bacteria might influence what we eat by manipulating signals in the vagus nerve, which connects 100 million nerve cells from the digestive tract to the base of the brain.

“Microbes have the capacity to manipulate behavior and mood through altering the neural signals in the vagus nerve, changing taste receptors, producing toxins to make us feel bad, and releasing chemical rewards to make us feel good,” said Athena Aktipis, co-founder of the Center for Evolution and Cancer.

Because of the gut’s profound influence on mental health in humans, many people call the intestines “The Second Brain,” since the microbes found throughout our bodies actually weigh twice as much as the human brain. While experiments that test the impact of gut bacteria on mental health are in the beginning stages, researchers seem to have found a clear link between having more robust gut bacteria and having a healthier brain.

In fact, another study found that young adults who eat more fermented foods, or those containing probiotics, have fewer symptoms of social anxiety than adults who don’t eat fermented foods. This might be attributed to the fact that the healthy bacteria lowers symptoms of anxiety in general in the gut. Studies into how gut health affects depression are ongoing, but we do know that most medicines for depression contain serotonin, a chemical found naturally in certain foods.

“Time and time again, we hear from patients that they never felt depressed or anxious until they started experiencing problems with their gut,” Dr. Kirsten Tillisch, lead author of the UCLA study, said. “Our study shows that the gut–brain connection is a two-way street.”

Our modern world runs largely on heavily processed, nutritionally-lacking foods, which may explain why we have so many digestive and mental health problems today. These toxic foods may explain why Western societies in particular have such high rates of anxiety, depression, bipolar disorder, and other common mental disorders.

So, what can you do to promote healthy gut bacteria to reduce anxiety and depression?

How To Treat Your ‘Second Brain’ For Anxiety and Depression

Eliminate, or greatly reduce, highly processed foods.

Consuming whole, fresh foods straight from nature will allow your digestive system to reset, therefore altering the bacteria in your gut. Opt for fruits, vegetables, nuts, seeds, sweet potatoes, fermented foods, and a small amount of unpasteurized, organic dairy, and lean, organic meats.

Related article: 6 Things People With A Healthy Gut Do Differently

Introduce more fermented, unpasteurized foods into your diet.

Fermented foods contain lactic acid bacteria, a beneficial bacteria that promotes good microbes within the gut. Examples of fermented foods that you can eat include tempeh (made from fermented soybeans), miso, kefir, sauerkraut, kimchi, kombucha, and yogurt.

Eat fiber-rich foods.

A study released by Professor Andrew Smith at Cardiff University in 2002 revealed that eating more fiber results in higher energy levels, more clarity, and a more positive mindset as opposed to eating a low fiber diet. Also, high fiber diets can reduce fatigue and lessen the risk of developing diseases of the bowels, including cancer.

High fiber foods basically include three food groups: fruits, vegetables, and starches such as brown rice, sweet potatoes, and other grains classified as complex carbohydrates.

Joe Alcock, Carlo C. Maley, C. Athena Aktipis. Is eating behavior manipulated by the gastrointestinal microbiota? Evolutionary pressures and potential mechanisms. BioEssays, 2014; DOI: 10.1002/bies.201400071
Matthew R. Hilimire, Jordan E. DeVylder, Catherine A. Forestell. Fermented foods, neuroticism, and social anxiety: An interaction model. Psychiatry Research, 2015; DOI:

Rachel Champeau. Changing gut bacteria through diet affects brain function, UCLA study shows. May 28, 2013. Retrieved from March 7, 2017.