Explaining the Donguibogam concepts of heat and dampness through modern medicine points directly to the interaction between capsaicin and our gastrointestinal tract. Capsaicin, the primary compound responsible for spiciness, activates TRPV1 receptors—which detect pain and heat in the body—rather than gustatory sense receptors. These receptors are distributed not only in the mouth but throughout the entire gastrointestinal tract. When capsaicin meets TRPV1 receptors in the gut, it sends pain signals similar to being burned by fire, stimulating the release of neuropeptides such as substance P and calcitonin gene-related peptide. These substances dilate blood vessels, trigger inflammatory responses, and significantly accelerate gastrointestinal motility.
When the gastrointestinal tract is excessively stimulated by capsaicin, peristalsis speeds up, rushing food through the small intestine and large intestine before proper digestion can take place. In the large intestine, water absorption cannot occur sufficiently, making watery osmotic diarrhea likely. In addition, when bile acid secreted during digestion is produced in excess due to capsaicin stimulation or descends into the large intestine unabsorbed, the bile acid itself irritates the intestinal barrier, further aggravating diarrhea.
Furthermore, capsaicin can temporarily compromise the protective gastrointestinal mucosa and increase permeability, creating a state similar to leaky gut syndrome. This allows harmful substances in the gut to enter the bloodstream more easily, risking a chronic inflammatory response. It can also disrupt the balance between beneficial bacteria and harmful bacteria in the gut microbiome, undermining long-term intestinal health.
Repeated consumption of spicy food sensitizes enteric nerves and can cause visceral hypersensitivity. This leads the gastrointestinal tract to overreact even to minor stimuli, predisposing one to symptoms resembling irritable bowel syndrome, such as abdominal pain, diarrhea, and constipation. For individuals who frequently eat spicy foods while under stress, an imbalance in the gut-brain axis may develop, creating a cycle where emotional stress triggers gut symptoms, which in turn produce more stress. Spiciness is not merely a matter of taste; it directly affects the overall balance and health of the body.
