Traditional Chinese Medicine (TCM) holds that "all the zang-fu organs can cause a cough, not just the lungs," while "exposure to cold and consuming cold drinks can injure the lungs." This tells us that although coughs are mostly caused by lung disorders that lead to the stagnation and adverse rising of lung qi, consuming cold and cool foods can also harm the spleen and stomach, impairing the spleen's function. This leads to the accumulation of dampness and the production of phlegm, which affects the lungs and subsequently triggers a cough. This is what TCM refers to as "the spleen is the source of phlegm production, while the lungs are the vessel for storing it."
Therefore, Tian Zhengjian reminds that people with a cough should pay attention to their diet. In particular, those with a deficiency of lung yang should avoid consuming excessively cold foods. For example, patients with chronic bronchitis should be cautious about consuming cold-natured foods. Excessive consumption of watermelon, banana, snow pear, pomelo, orange, persimmon, and cooling herbal teas can disrupt the body's yin-yang balance, leading to a deficiency of yang and causing a cough. It is worth noting that some people believe snow pear moistens the lungs and can stop a cough, but this is not entirely accurate. Snow pear is only suitable for relieving coughs caused by lung heat; it is not appropriate for patients with lung deficiency, as it can worsen the cough. Furthermore, children have weaker spleen and stomach functions and should strictly avoid cold foods to prevent aggravating their condition and prolonging recovery. Conversely, for patients with a cough, proper dietary conditioning can often yield twice the results with half the effort.