The process through which we perceive smell is far more complex and delicate than one might think, much like an orchestra. When olfactory receptor cells in the nasal cavity detect odor molecules, this signal passes through the olfactory bulb of the brain to the cerebral cortex and the limbic system, which governs emotions and memories. This is why certain smells evoke vivid memories or instantly shift our mood. Losing the sense of smell means that a problem has occurred somewhere in this delicate neural circuit.
Modern medicine largely divides anosmia into two categories. First, there is conductive anosmia, where odor molecules cannot reach receptors due to inflammation, cysts, or severe edema inside the nose. This is frequently seen when chronic rhinitis or sinusitis worsens. This can be viewed as aligning with what Donguibogam describes as the obstruction of lung qi. Second, there is sensorineural anosmia, where olfactory nerve cells or the olfactory center of the brain itself are damaged. It can appear due to viral infections (which many people experienced recently as a long COVID sequela), head trauma, certain medications, and even as an early symptom of neurodegenerative diseases such as dementia.
What is more important here is that anosmia may not be merely a nasal issue, but an SOS signal from the body indicating systemic health imbalance. Just as Korean medicine speaks of harmony between the lungs and kidneys, modern medicine also sees that chronic inflammation, hypersensitivity reactions of the immune system, endocrine disruption from stress, and nutritional imbalances profoundly affect olfactory function. For instance, chronic stress causes adrenal fatigue, which disrupts our immune response and can worsen inflammation of the nasal mucosa. In addition, micronutrient deficiencies such as zinc, vitamin A, and vitamin B12 are essential for nerve regeneration and the health of olfactory receptors, and a lack of these can diminish olfactory function.
Recent research has also revealed that the link between gut health and brain health, known as the gut-brain axis, can influence olfactory function. When the balance of gut microbiota is disrupted, it triggers a systemic inflammatory response, which affects brain function and the nervous system, potentially causing problems with odor perception. In other words, being unable to smell well is a valuable signal indicating that, beyond a localized issue of the nasal mucosa, it may be time to comprehensively check our immune system, nervous system, endocrine system, and even digestive system. Do not miss the small signals your body sends.
