As our quality of life improves, so does our dietary expenditure, which has led to the emergence of numerous health issues. Experts suggest that one's tongue can reveal the body's condition. So, do you know what causes a thick yellow coating on the tongue? Below, we'll explain why this occurs and what it signifies.A normal tongue bears a thin, white, and moist coating called tongue coating. It consists of shed keratinized epithelium, saliva, bacteria, food debris, and exuded white blood cells. Under normal circumstances, chewing, swallowing, and the cleansing action of saliva and food continuously remove substances from the tongue's surface, leaving only a thin white coating.When illness occurs, reduced food intake or consumption of only soft foods diminishes chewing and tongue movement, or decreases saliva secretion, leading to thicker tongue coating. In healthy individuals, the coating is generally thin and evenly distributed across the tongue surface, slightly thicker in the middle and root areas.
As tongue coating originates from stomach qi, and all five viscera and six bowels receive qi from the stomach, changes in coating reflect the cold, heat, deficiency, or excess within the viscera, as well as the nature of pathogenic factors and the depth of disease location. Visual diagnosis of tongue coating involves examining both its color and texture.
Coating Color: This refers to the tongue coating's hue. Pathological coating colors primarily include white, yellow, and grayish-black coatings. Occasionally, green coating may appear (often transforming from white coating, commonly seen in warm epidemics or damp-heat conditions, indicating stagnant damp-heat) or moldy-sauce coating (a red coating with black and yellow discoloration, often observed in food-stagnation heatstroke or prolonged internal heat accumulation, primarily in chronic damp-heat diseases).