Your Gut Microbiome Could Be Worsening Your Depression

The idea of ingesting someone else’s poop might sound like a dare gone wrong, but fecal matter transplants are a promising new treatment for mental health. That’s because poop transplants supply “good bacteria” to the colon and restore a healthy balance to the gut microbiome.

Scientists are understanding the importance of taking care of your gut. Think about all the times you felt butterflies in your stomach or felt queasy minutes before a first date. Your gut has its own private line to the brain and the two organs communicate so much, it gets a say on our bodily processes. 

“Our gut and brain were formed from the same fetal tissue in the womb, so they’re forever linked through the gut-brain axis connection,” says Gemma Stuart, the founding owner of Gutsy Health. “The trillions of microbes in our gut can influence our body weight, our response to infection, our immunity, and our mood.” It’s no wonder doctors refer to the gut as our second brain.

So when the trillions of microorganisms that call the gut home are not doing so well, they alert the brain for help. These distress signals show itself in many ways, including as signs of depression and loneliness.

Imbalance of the gut microbiome

To maintain a healthy gut, there needs to be more good than bad microbes. Shifting the balance toward more harmful bacteria makes it harder for good microbes to grow and prosper. There is some research linking certain bacterial families to depressive symptoms. Authors of a 2022 study in Nature Communications examined over a thousand poop samples of people with depression and narrowed down the culprits to thirteen bacterial strains. These bacterial species are involved in the creation of brain chemicals that promote depression. 

Low serotonin production in the gut

Serotonin is the key brain chemical involved in regulating our moods and emotions. At normal levels, this “happy hormone” keeps you calm and emotionally stable. About 95 percent of serotonin is made in the gut.

One school of thought behind depression is that it’s associated with low serotonin levels, though this theory has stirred up debate in recent years. Some research suggests a gut imbalance can throw off the production and delivery of serotonin to the brain if there are not enough bacterial species to make the chemical.

Gut inflammation

Inflammation in the gut is strongly linked to an increased risk of depression. One explanation is that when the brain gets word of an immune response in the gut, the brain deploys its own defense. The increase in neuroinflammation is considered a path toward depression as it activates an intense and chronic stress response. Research suggests that inflammatory proteins deplete the existing supply of serotonin and affect production for more. The immune cells also slow down the process of creating new brain cells. A failure to produce new neurons is associated with depression because it makes it harder to separate negative thinking and memories.