How Diet and Gut Bacteria Affect Your Mood


Inside your gut lives a community of bacteria, protozoa, fungi, and viruses that function to keep you alive and well.

This community of microscopic organisms is called the gut microbiome. We give these organisms food and a place to live. In return, they perform vital digestive, immune, brain, and hormonal functions for us.

“Recent clinical and preclinical studies are demonstrating that gut microbiota play a central role in contributing to normal, healthy homeostasis [stability], and that their disruption contribute to risk of mood and other [central nervous system] disorders,” said Jane Foster, Ph.D., of McMaster University in Canada.

It Goes Both Ways

The brain-gut communication network is called the BGM, or brain-gut-microbiota axis. The brain affects gut processes via the BGM, and messages from the gut influence brain processes.

For instance, our vagus nerve is part of the BGM. It enables signals to be delivered between the brain and gut. Many positive effects that gut bacteria have on brain function require vagal nerve activation. Conversely, neural activity travels down the vagus nerve influencing the gut’s movements and secretions.

Part of this give-and-take between the brain and gut affects the regulation of our mood. Disruption in this system is associated with symptoms of stress, anxiety, and depression.

Stress and Gut Health

When the gut microbiome is unhealthy, it stimulates the release of stress hormones via the hypothalamus, pituitary, and adrenal glands—worsening disruption of the microbiome. Simultaneously, any external stress we experience triggers the release of pro-inflammatory chemicals (e.g., cytokines) that negatively alter gut bacteria and our intestinal lining.

Beside stress, our diet, genetic heritage, age, metabolism, geography, and antibiotic use affect the gut’s health. The two factors we have the most control over are diet and antibiotic use.

Diet and Gut Health

Nutrient-rich foods, full of complex carbohydrates and fiber, support a healthy microbiome. The typical Western diet of highly processed foods loaded with unhealthy fats and sugars, and often contaminated with pesticides, contributes to gut bacteria imbalances.

A fiber rich diet, for instance, raises our microbes short chain fatty acid production, stifling the growth of harmful bacteria. Consuming a lot of refined sugar has the opposite effect, allowing unwanted bacteria to thrive.

We can also support our gut health by eating probiotic foods that replenish our microbiome—foods such as kefir, kimchi, fermented vegetables, and minimally processed yogurts. This is especially important following treatment with antibiotics that can wipe out healthy intestinal bacteria.


Probiotic supplementation might someday be part of treatment plans for psychological and central nervous system disorders. Research is discovering that certain bacteria actually carry and deliver neuro-active substances such as serotonin. These “psychobiotic” bacteria might someday be considered unique forms of psychotropic palliatives.

“I think it is important for psychiatrists to pay attention to their patients’ diet,” Foster said. “Lifestyle changes can contribute to mental health. I also think that probiotics might potentially be beneficial in the treatment of psychiatric patients.”

Source: psychiatry advisor
Photo credit: Keoni Cabral


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