Got winterblues? Your gut can help! The microbiome and depression

We already know that the trillions of microbes that make up our microbiome, influence the health of our skin, digestive system and many other physical processes. A lesser known fact is, that it also greatly affects our mental health. We all have experienced our physical and mental state influencing each other first-hand: Feeling terrible because of pain or getting an upset stomach due to worry, stress or even excitement. There is even a term “hangry”, that describes getting angry as a result of not having eaten in a long time.

 Symptoms like brain fog, headaches and cognitive or memory problems are also linked to an impaired gut microbiome. As are psychological conditions like anxiety or depression. The latter is especially prominent in the darker winter months, therefore also called seasonal affective disorder (SAD) (1). A 2017 meta-analysis (2) showed that Irritable Bowel Syndrome (IBS) patients have higher levels of depression and anxiety compared to healthy people.

 Let’s explore the different factors that are part of the relationship between the microbiome and our mental wellbeing: The “gut-brain-axis” forms the connection between the brain and the gut – our “second brain”, involving the nervous system, neurotransmitters and our gut microbes.

 The gut’s own nervous system is called the enteric nervous system which consists of 100 million neurons. The vagus nerve is the largest nerve of the parasympathetic nervous system and acts like a super highway between the brain and the gut. It allows them to “talk” to each other by sending information about what’s going on in our gut to our brain and vice versa. It’s important to note, however, there is actually much more information going from the gut to the brain than the other way around! This means it’s not our brain calling the shots, but rather the tiny friends in our guts.

 These microbes also produce nutrients like vitamins and short-chain fatty acids (SCFAs) that are necessary for a healthy brain and mental state. Microbial dysbiosis can lead to chronic inflammation which – among other diseases like rheumatoid arthritis, cardiovascular disease and cancer – has also been linked to Alzheimer’s disease. (3) 95 % of the serotonin (4) and 50 % of the dopamine (5) in our bodies are made in the gut. These neurotransmitters play a crucial part in modulating our moods and cognitive processes.

With all that being said, we now have powerful new ways of caretaking our minds. Lifestyle interventions like a healthy diet and exercise support our microbes and may thereby also improve our mental health.

So: Happy microbiome, happy mind.