When looking at the Korean medicine concept of fire through a modern scientific lens, we can discover a remarkable connection within our bodies: the close interaction between stress and the autonomic nervous system, as well as the gut-brain axis.
Severe stress or chronic anxiety excessively activates the body's sympathetic nerve. The sympathetic nerve is an emergency system that makes us fight or flee when faced with danger. When this system turns on, the body prioritizes supplying blood to muscles or the brain instead of digestive organs for survival, much like temporarily closing a food warehouse when war breaks out. When blood flow volume to the stomach and intestines decreases, digestive function naturally declines, and the secretion of mucus that protects the stomach wall also decreases. As the protective barrier of the stomach wall thins, it becomes vulnerable to inflammation from direct attacks by gastric acid.
In addition, under stressful situations, the brain excessively secretes stress hormones like cortisol. This cortisol not only directly promotes gastric acid secretion, but also impairs the regeneration capacity of the gastric mucosa and hinders blood circulation in the stomach. As a result, excessive gastric acid is secreted while the stomach wall becomes weak, leading to painful conditions like nervous gastritis or reflux esophagitis. Symptoms of reflux esophagitis that burn up to the throat can be described as an inflammatory reaction resulting from repeated exposure of the weakened esophageal mucosa to gastric acid.
More importantly, the gut-brain axis theory demonstrates that our brain and gut are directly connected via the vagus nerve. When the brain perceives stress, that signal is transmitted to the gut, altering digestive fluid secretion, intestinal motility, and even the gut microbiota environment. Various problems can arise, such as digestion slowing down or becoming too fast, and inflammation worsening as the balance between beneficial gut bacteria and harmful bacteria is disrupted. In other words, the Korean medicine view that fire burns body fluids and dries out the stomach can be explained in modern medicine through stress-induced gastric hyperacidity, gastric mucosa damage, deepening of inflammatory responses, and digestive hypofunction. The stomach is not merely an organ that digests food, but a second brain and an emotional vessel that reflects the distress of the mind.
