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Mind & Mood

Gastrointestinal Issues: What’s Your Brain Have to Do with It?

woman holding her stomach

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Research Shows
Gut Differences in People with Mood Disorders
A major focus of research right now is understanding the role of the gut microbiome, which refers to the trillions of bacteria living in our large intestine. Scientists have observed that gut microbial communities are different in people with mood disorders. 
One experiment tested what would happen if scientists transferred the colon contents of stressed-out rodents into the colons of a control group raised in a sterile environment. The control group began demonstrating anxious behaviors. Scientists believe that these results and the research linking gut bacteria differences in people with mood disorders suggest a connection between mood and bacterial communities in the gut.

Have you ever become so excited or upset that it caused you to have to run to the bathroom? What about getting news so bad it made you feel nauseated? If you’ve ever experienced these symptoms, you’ve felt the brain-gut connection firsthand. 

Linda Lee, M.D., director of the Johns Hopkins Integrative Medicine and Digestive Center, discusses the connection between the brain and the gut, and how gastrointestinal (GI) issues impact the brain. She notes that while digestive disorders often affect women differently than men, both are impacted by this connection. 

The Brain-Gut Connection

According to Lee, we definitely have a brain-gut connection. “We experience it every time we feel butterflies in our stomachs, typically when we’re excited, in love or scared. When this happens, we will sometimes experience GI symptoms.”

Science is beginning to understand the process behind this link, which ultimately relates to hormones released from different parts of our brain — yes, they are in your head, as well as other places — when we are particularly stressed or excited. 

“These chemicals circulate in the bloodstream and can affect the sensitivity and function of nerves in the wall of the gut,” says Lee. “We collectively refer to these nerves as the enteric nervous system.”

Irritable Bowel Syndrome and the Brain

Researchers are starting to understand how activity within the gut can also affect the brain. One example is irritable bowel syndrome (IBS), a condition that affects up to 15 percent of people in the United States and impacts women twice as often as men. If you have IBS, the nerves in your gut are extremely sensitive, and the brain processes these signals from your gut differently than it would if you did not have IBS. Even small amounts of gas can trigger pain, bloating, constipation or diarrhea.

Gut Issues and Mood

Lee has cared for many people with gut issues in the Johns Hopkins Women’s Digestive Health Program, often personally observing how these problems can affect a woman’s mood and sense of well-being. For instance, she says some people with chronic constipation also have a depressed mood or even headaches. 

While many natural health practitioners harp on the negative effects of toxins in the body, Lee says that’s not what’s behind the brain-gut connection. “I believe it’s because being constipated actually causes the enteric nervous system to send certain signals to the brain, which then trigger a cascade of feelings,” she says. 

“What we don’t know yet is how we can manage bacteria in our gut to achieve changes in our mood,” says Lee. “That’s where the future lies.”

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