Brain Anatomy 101: The Effect of Stress on Your Gut

In today’s blog post, I want to talk about a way to recognize whether your body is under stress: by looking at the state of your gut. The title already gives it away. When you experience a lot of stress, it has a significant impact on your digestive system.

As you may already know, your brain and body are closely connected. When your brain signals that you are stressed, your body quickly responds physically. Your brain releases higher levels of the stress hormone cortisol, which affects various functions in your body.

For example:

• Your blood sugar rises, giving your muscles more energy

• Your blood pressure, heart rate, and breathing increase, delivering oxygen faster

• More blood flows to your muscles, increasing muscle tension

These responses are helpful when you are in real danger, but harmful when they are constantly activated without a real threat. One of the main consequences is that your digestion slows down. In other words, ongoing stress disrupts proper digestion.

You might wonder how that works exactly.

When your body is under stress, the hormone gastrin produces less mucus and stomach acid. Both are essential for breaking down food. When digestion slows, food stays in your stomach longer than it should. Over time, your stomach becomes overly full. The valve to the small intestine only opens at a certain acidity level (around pH 2–3), so delayed digestion can cause pressure buildup.

This pressure can push stomach contents back toward the esophagus, leading to acid reflux. Because the esophagus is not protected against stomach acid, this can cause a burning sensation, pain, nausea, or burping.

Gastrin also plays a role in maintaining the protective mucus layer of the stomach lining. When food lingers too long, it can irritate this lining, potentially leading to damage. This may result in symptoms such as heartburn, bloating, abdominal pain, or cramps.

When food eventually reaches the small intestine, digestive enzymes are needed to break it down into absorbable nutrients. These enzymes depend on nutrients such as zinc. However, stress depletes zinc levels. As a result, your body may struggle to absorb nutrients properly, which can lead to deficiencies in iron, vitamin B12, and vitamin D.

Finally, undigested food reaches the large intestine. While beneficial gut bacteria thrive on fiber, they do not respond well to poorly digested proteins and fats. This imbalance can lead to symptoms such as diarrhea, urgency, cramps, inflammation, and even food sensitivities.

So if you regularly experience the symptoms mentioned above, it is important to consider that stress could be a contributing factor.