After a quick search on google, I discovered that I was not alone in my problem of ice-cream induced coughing fits. After quickly researching the topic I was disappointed: I had failed to find a satisfying explanation to the problem. My most promising find was discovering that dairy products induce mucus production; however after reading a study published on PubMed, I found this notion to be an urban legend. The study concluded that ‘no statistically significant overall association can be detected between milk and dairy product intake and symptoms of mucus production in healthy adults’. (1)
After this setback, I began hypothesising more scientifically-sound solutions. The answer came to me weeks later when I was having a coughing fit, and it is as follows:
When a person consumes ice-cream, it travels down their oesophagus, which is in contact with their trachea, thereby cooling down their trachea. Mucus present in the trachea would usually be swept up to the back of the throat by cilia (tiny, hair-like projections on the epithelial lining of the trachea); however when the trachea is cooled by ice-cream, the mucus hardens and becomes thicker, making it more difficult for the cilia to sweep it up. The body’s response to this is to cough up the hardened mucus, to prevent the build-up of pathogens which could lead to an infection. This response is especially significant for people with respiratory diseases such as asthma because they are already secreting abnormal amounts of mucus due to their disease.
According to my hypothesis, the consumption of any cold food or beverage should cause this coughing response. The reason that ice-cream is a more significant trigger for the response is because it is a colloid (neither a solid nor a liquid). It has a higher viscosity than most liquids, so will slowly trickle down the oesophagus, spending more time cooling the trachea and therefore making the mucus thicker than other cold beverages would. This also explains why thick milkshakes cause the same effect.