From What You Eat to Your Nose: Rhinitis After Certain Foods, the Link Between the Spleen and Stomach and the Lung

The observations recorded in Donguibogam align closely with modern clinical understanding. Current medicine interprets nasal symptoms occurring after certain foods as presentations of food allergic rhinitis or food hypersensitivity. While the digestive organs and respiratory system might appear unrelated, the human body functions as an interconnected network. The intestines host more than 70 percent of the immune system and maintain direct communication with the nervous system, earning them the designation of the second brain. Food allergic rhinitis generally operates through two pathways. The first is an immediate allergic reaction mediated by immunoglobulin E antibodies. When the body misidentifies a dietary protein as a harmful allergen, it produces an IgE antibody. This antibody binds to a mast cell; upon subsequent exposure to the allergen, the mast cell rapidly releases inflammatory mediators like histamine. Histamine dilates local blood vessels and stimulates mucus production, provoking typical allergic rhinitis signs such as nasal congestion, rhinorrhea, and sneezing. In this scenario, the immune system mounts a sudden defensive response to a specific dietary trigger. The second mechanism involves delayed food hypersensitivity or non-immunological pathways that do not directly involve IgE antibodies. Rather than surfacing instantly, these reactions often develop gradually over hours or days, triggered by sensitivity to compounds like amines, salicylates, or food additives, or by a deficiency in digestive enzymes. Intestinal barrier integrity plays a central role here. The intestinal barrier functions as a protective shield against harmful foreign particles. When prolonged stress, irregular diet, or frequent antibiotic use damages this lining, intestinal permeability rises, a state often described as leaky gut syndrome. As the barrier weakens, incompletely digested food particles and toxins enter the bloodstream, triggering a systemic inflammatory response. These circulating inflammatory signals travel through the blood flow to reach the nasal mucosa, intensifying allergic rhinitis. Recent scientific attention focuses heavily on the gut-lung axis, demonstrating that intestinal balance directly affects respiratory wellness. When the balance between beneficial bacteria and harmful bacteria is disrupted, resulting in gut dysbiosis, the normal regulation of inflammatory cytokines collapses. These inflammatory signals can be transported through the circulation directly to the lungs and upper airway mucosa, causing hyperactivation of the immune response and driving rhinitis symptoms. The ancient premise linking the spleen and stomach to the lung is thus reaffirmed through modern immunology, demonstrating that nasal balance relies deeply on systemic gut health.