In modern times, we can understand the wisdom of the Donguibogam more clearly through the concept of the gut-brain axis. The brain and the gut form an intricate network that constantly exchanges signals, which is why the gut reacts sensitively when we experience stress or emotional shifts. The coldness of the navel described in the Donguibogam goes beyond mere physical hypothermia and is deeply linked to autonomic nervous system imbalance in modern medicine. When sympathetic nerves are excessively activated by stress and tension, our body perceives it as a dangerous situation and prioritizes blood supply to the heart or muscles rather than the digestive organs. In this process, blood flow volume to the intestines decreases, intestinal peristalsis slows down or becomes irregular, and the secretion of digestive enzymes is suppressed. This leads to intestinal hypofunction, indigestion, and abdominal discomfort, which aligns with the concept of cold qi reducing digestive capacity. Furthermore, such chronic stress can heighten intestinal sensation, potentially causing visceral hypersensitivity where one feels excessive pain from normal stimuli. An imbalance in the gut microbiota is also a significant factor. When harmful bacteria multiply, the intestinal mucosa is easily damaged and prone to inflammatory reactions, potentially causing issues like leaky gut syndrome and worsening irritable bowel syndrome symptoms such as abdominal pain, diarrhea, and constipation. The vagus nerve is a key neural pathway connecting the brain and the gut, forming an important part of the parasympathetic nervous system and deeply engaging in digestion, immunity, and mood regulation. When vagus nerve activity decreases due to stress, intestinal motility drops and digestive secretion declines, which corresponds to the indigestion, abdominal pain, and diarrhea caused by the coldness of the navel in the Donguibogam. Chronic stress promotes the secretion of stress hormones such as cortisol and can affect serotonin metabolism in the intestines, making intestinal motility abnormal. About 95% of the serotonin in our body is produced in the gut. This serotonin is deeply involved in intestinal motility and sensory regulation, and an imbalance leads to intestinal trouble. All these processes manifest as abdominal coldness and unstable digestive symptoms.
