Much like the qi circulation described in Korean medicine, the body communicates through complex neurological and endocrine networks. Small intestinal bacterial overgrowth (SIBO) can be understood as a modern condition where the transmission and transformation functions of the large and small intestines described in Donguibogam are disrupted. While the small intestine's primary role is nutrient absorption, problems arise when bacteria that belong in the large intestine proliferate excessively in the small intestine.
Under normal conditions, the small intestine houses relatively few bacteria. Gastric acid serves as an initial defense, and the migrating motor complex moves food remnants and bacteria downward toward the large intestine. However, when this defense system weakens due to stress, acid suppressor use, hypomotility of the gastrointestinal tract, certain antibiotics, or systemic conditions such as hypothyroidism, bacteria from the large intestine reflux or overgrow within the small intestine. These bacteria ferment dietary carbohydrates, producing substantial volumes of hydrogen, methane, and hydrogen sulfide. These gases result in abdominal distension, pain, belching, flatulence, and alternating diarrhea or constipation. The gut becomes stagnant and full, resembling the damp-heat described in Donguibogam.
Furthermore, small intestinal bacterial overgrowth extends beyond digestive discomfort to affect overall systemic health. The proliferating bacteria can damage the small intestinal mucosa, leading to leaky gut syndrome. When gaps develop in the intestinal mucosa, incompletely digested food particles and bacterial toxins enter the bloodstream, triggering a systemic inflammatory response, overburdening the immune system, and raising the risk of autoimmune disease. Through the gut-brain axis, this process also influences brain function, worsening neurological symptoms such as anxiety, depressed mood, and impaired concentration. The traditional observation that an unsettled gut leads to an unsettled mind aligns with modern neurology.
Small intestinal bacterial overgrowth is present in a notable proportion of people with irritable bowel syndrome, yet it frequently goes unrecognized in routine examinations and remains inadequately addressed. Diarrhea-predominant small intestinal bacterial overgrowth is primarily linked to hydrogen-producing bacteria, while constipation-predominant small intestinal bacterial overgrowth is closely associated with methanogens. Care approaches need to differ based on gas characteristics and individual symptoms. Simply taking a digestant or increasing dietary fiber may not address the underlying issue, making consultation with a healthcare professional essential for an accurate evaluation and a clear management plan. The health of the intestines remains central to the wellness of the whole body.
