In recent years, researchers have been uncovering what's sometimes called the "gut-brain axis" — that is, the connection between gut health and mental health. The latest information to illuminate this phenomenon comes from a study published in Gut, which found that pregnant women with inflammatory bowel diseases like like ulcerative colitis and Crohn's disease are at a greater risk for anxiety, depression, and substance use disorders after childbirth.
The researchers analyzed data on 3721 Canadian women who gave birth between 2002 and 2014. 22.7 percent of those who suffered from inflammatory bowel diseases developed a mood or anxiety disorder or an alcohol or substance use disorder after giving birth, compared to 20.4 percent of women who did not suffer from inflammatory bowel disease — a small but significant difference. There wasn't a difference between the mental health of the two groups during pregnancy, however.
The idea that gut issues increase risk for mental health problems wasn't actually the part of the discovery that was new. "It was known that there was a connection between mental illness and IBD in general," lead author Simone Vigod, MD, chief of the department of psychiatry at Women’s College Hospital, tells Bustle. "But it had not previously been explored around the time of pregnancy."
Pregnancy is an important time in this regard, however, because women are often in healthcare settings during pregnancy, so it's a fairly easy time to introduce interventions, Dr. Vigod says. In addition, it's important to prioritize women's mental and physical health during this time because it will affect the health of their families as well.
It's not clear what caused the link between gut health and mental health among the women in the study. It could be due to direct effects that the gut has on the brain, Dr. Vigod says: "It may be that people who have inflammatory processes happening in their gut could also be at greater risk for having them happening in their brain, resulting in a mental illness." Or, it could come from the emotional impact of dealing with a chronic illness on top of a newborn.
A possible implication of the study is that pregnant women might be able to prevent postpartum mental illness by improving their gut health. But more research would be needed to determine how to accomplish this and whether it would be effective, Dr. Vigod says.
What is clear, though, is that this is only one of many ways that gut health impacts mental health. Another recent study published in Nature Microbiology, for example, found a link between depression and low levels of gut bacteria called coprococcus and dialister. Another study in Science Translational Medicine found that mice that received fecal transplants from people with irritable bowel syndrome and anxiety developed symptoms of anxiety as well. On the flip side, a study in the British Journal of Nutrition found that probiotics improved people's moods as much as anti-anxiety medication.
"Studies have shown that depression, bipolar disorder, schizophrenia, and other psychological or neurological problems may be influenced by a disruption in the microbiota," Tieraona Low Dog, MD, chief medical advisor at MegaFood, tells Bustle. "Researchers speculate that disruption of the microbiome can cause the immune system to overreact and contribute to inflammation, leading to the development of symptoms of disease that occur throughout your body, including your brain."
It's still coming to light what exactly a healthy microbiome looks like, as many bacteria can be either good or bad depending on the amount and other factors, but it seems likely that basic habits that are good for the gut could benefit the brain as well. Low Dog recommends a plant-rich, low-sugar diet, probiotics (there are even some specifically for mental health), and fermented foods to optimize your gut health as well as your mental health.