You don’t need a PhD in physiology to know that stress can be hard on the stomach. We’ve all done our own experiments on the subject, intentionally or not. Black people, in particular, tend to be more stressed due to the several stress factors they may have to deal with on a daily basis (occupation, finances, relationships, racial bias, and violence, etc.)
The impact of stress on the stomach goes far beyond indigestion, however. In recent years, doctors have uncovered a remarkably complex connection between the brain and the digestive system. The entire system is extremely sensitive to our moods. In fact, experts now see stress as a major player in a wide range of digestive problems, including irritable bowel syndrome, indigestion, and heartburn.
People with digestive problems often scoff at the idea that stress could be at the root of their problems. To them, it sounds like “blaming the victim.” Robert Sapolsky, a Stanford University stress expert and author of the best-selling book “Why Zebras Don’t Get Ulcers (Henry Holt and Co., 2004)”, says his discussion of stress and irritable bowel syndrome prompted “semi-irate” letters from readers.
But experts who study the link between stress and digestion aren’t searching for people to blame. Instead, they’re looking for scientific explanations for some of life’s most common maladies. By understanding how stress affects our bodies, they’re opening new avenues for prevention and treatment of many conditions.
A two-way street
We all talk about “gut feelings,” but few of us really appreciate the amazingly strong connections between the brain and the digestive system. The stomach and intestines actually have more nerve cells than the entire spinal cord, leading some experts to call the digestive system a “mini brain.” A highway of nerves runs directly from the real brain to the digestive system, and messages flow in two directions. Consider this: 95 percent of the body’s serotonin — a hormone that helps control mood — is found in the digestive system, not the brain.
As Sapolsky writes in “Zebras”, there are sound reasons why our digestive system should pay such close attention to our brains. In times of stress, our bodies are designed to focus on the things that can help us stay alive. When our ancestors had to fight off slavery, they didn’t want to waste any energy on less important things like proper digestion.
When the brain feels severely stressed, it unleashes a cascade of hormones that can put the whole digestive system in an uproar. The hormones have different and sometimes contradictory jobs. For example, the hormone CRH (short for corticotropin-releasing hormone) is one of the body’s main alarm bells. In stressful situations, the brain pumps out CRH to tell the adrenal gland to start making steroids and adrenaline, chemicals that can give you the strength and energy to run or fight your way out of trouble.
CRH also turns off appetite, which explains why some people can’t eat anything when they’re stressed. At the same time, the steroids triggered by CRH can make a person hungry, which is why some people fight stress with ice cream, chocolate, or potato chips.