How Can Healthy Guts Help Unhealthy Minds?

An ongoing clinical trial is hoping to discover whether bipolar disorder is among the ailments that can be treated with fecal transplants.


It’s a concept that may have seemed farfetched not too long ago, but researchers are taking an interest in using fecal transplants to improve mental health. Clinical trials are now underway, and this is only the beginning as we work to understand the gut-brain connection.

Our gut is teeming with friendly microbes. This community is called the microbiome, and it helps us digest food and protects us against infections.

With a wealth of their own genes, they create a lot of their own molecules. These include neurotransmitters that are crucial to mental health, like serotonin, dopamine and gamma aminobutyric acid (GABA). Changes to the microbiome mean these same molecules are often lacking in people with depression, anxiety, bipolar disorder, and other mental illnesses.

Stress and anxiety have an impact on the body. For one, they trigger inflammation, and that can alter the gut microbiome. Previous studies have also shown that transferring stool samples from people with depression or anxiety into mice transfers transfers symptoms.

So the gut and the brain each influence each other, but could stool samples from ultra-healthy donors transfer wellness?

Trial seeks benefits of fecal transplants on mental health

Dr. Valerie Taylor is at the helm of an ongoing clinical trial in Toronto on the effect of fecal transplants on bipolar disorder. She’s the head of the University of Calgary’s psychiatry department and an adjunct scientist at Women’s College Research Institute.

Knowing that the wrong stool samples could introduce mental illness in recipients, donors go through rigorous screening to make sure they’re exceptionally healthy. From there, the fecal transplants will be introduced by colonoscopy in patients with bipolar disorder. Some patients will receive their own stool as a control, and the remaining participants will get the donor stool as active treatment. All participants will continue to receive a currently accepted approved therapy for bipolar depression.

Taylor will look for changes in the established gut microbiota and their metabolites in stool and blood serum samples. Changes in mood rating scales will also be assessed. As a randomized controlled trial, no one will know which patient is in which group until after the study concludes.

The frontiers of this field are extending in even more directions. Fecal transplants are already confirmed as a curative treatment for C. difficile infections. Canadian clinical trials are also underway for other intestinal and metabolic disorders, like obesity, diabetes, inflammatory bowel disease, and Crohn’s disease. Other current fecal transplant trials target diseases like multiple sclerosis and cancer.

We are starting to understand that human health depends on an entire ecosystem of life that exists in and on our bodies. It’s a symbiotic relationship that goes beyond nutrition and has far-reaching influences on our well-being. Feeding the needs of our microbiome may carry benefits that are hard to imagine, but these mysterious connections could provide real solutions for medical conditions we struggle to treat.

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Karyn Ho is a science animator and engineer who thrives at the interface between science, engineering, medicine, and art. She earned her MScBMC (biomedical communications) and PhD (chemical engineering and biomedical engineering) at the University of Toronto. Karyn is passionate about using cutting edge discoveries to create dynamic stories as a way of supporting innovation, collaboration, education, and informed decision making. By translating knowledge into narratives, her vision is to captivate people, spark their curiosity, and motivate them to share what they learned.