The intricate, sensitive connection between the mind and the gut

I’d been stressed since giving birth (the second time), and a medication I received during labor was making breastfeeding painful. I was already anxious about my return to work with two kids, an early daycare pickup, and childcare costs doubling. I was frustrated by a lack of sleep and regularly went for cheesy pasta casseroles and banana bread over vegetables. When my symptoms started escalating—to stomach pains and heartburn, and later to achy joints and rashes—I made my way through more than a dozen doctors and medications searching for a diagnosis. Months later, I finally came to believe it had all started in my mind. “When you’re stressed, your gut is a different gut,” says Emeran Mayer, a gastroenterologist, neuroscientist, and UCLA professor who studies how the digestive system and nervous system interact in health and disease. “The brain and the gut are so closely connected, you almost have to look at it as one unit.”

Emotions and the stomach are linked. I knew that. Like anyone, I’ve felt butterflies in my belly before speaking in front of a group. What I didn’t realize was the profound and long-lasting effect chronic stress can have on our gut, specifically by altering its composition, disrupting, and even disabling our microbiota—the 100 trillion microorganisms living in our stomach that help us process food and maintain a healthy immune system. Microbiome research has exploded in recent years as scientists seek to better understand this microscopic ecosystem operating inside our bodies. “The Mind-Gut Connection,” Mayer’s recently published book on this topic, explores the constant dialogue between our brain, gut, and gut microbiota. It delves into what can go wrong when communication between the three breaks down, and how to help reverse ill effects. The necessary communication starts in the brain. That’s where stress stimulates the release of a hormone called the corticotropin releasing factor (CRF), which triggers two messages to the body: one is a spike in the stress hormone cortisol. The other is a signal that travels through our autonomic nervous system to the gut where it can interfere with digestion and cause symptoms like belly pain, bloating, and irregular bowel movements.  Nerve signals can also change the composition of the gut microbes, influence their behavior, and make the lining of the gut more permeable, eventually leading to a “leaky gut.” When this happens, gut microbes and food components gain access to the gut’s immune system, resulting in low-grade inflammation that can spread throughout the body. A leaky gut can increase the risk of developing a host of other health problems, including food allergies, autoimmune diseases, and possibly even depression. When blood work showed I’d developed a sensitivity to more than a dozen foods I’d eaten my whole life without a problem, and my physical symptoms worsened over time, I became even more anxious. It was a vicious loop.