By: Helen Beilinson
Occasional coughing is completely normal. It’s one mechanism our bodies use to remove foreign objects or accumulated secretions from our lungs and throat. However, when a cough becomes chronic (defined as lasting at least two months in adults or one month in children), this could be the sign of something more serious. Chronic coughing is not just annoying and uncomfortable; it can cause exhaustion by keeping you up at night, lightheadedness, and even rib fractures in severe cases. Chronic choughs can be caused by a variety of things; the most prominent sources are tobacco smoking, asthma, acid reflux (also as gastroesophageal reflux disease (GERD)), and postnasal drip. However, various respiratory infections, damage caused by past infections or chronic inflammation, such as chronic bronchitis, and blood pressure drugs have also been linked to chronic coughing. Of course, the best way to treat chronic coughing would be to battle the cough at the source of the problem to try to eliminate what was causing the coughing. But sometimes patients just want to subdue the cough, to find some relief, and a get good night’s sleep.
The most common method of treating coughing is by using cough suppressants, or antitussives, containing codeine, a mild, plant-derived opiate. Codeine is a fantastic cough suppressant, but using it in large doses is unhealthy due to the side effects, which include drowsiness, vomiting, constipation, and addiction. Although this article may have started on a slightly sour note, I come bearing good news: a substance in cocoa and chocolate has been shown to suppress coughing more effectively than codeine, without the unwanted side effects. Which means if you have a persistent cough—eat chocolate!
In the 1970’s, asthma was being treated with a compound called methylxanthine theophylline, a synthesized molecule. Authors of a study published in 2004 wanted to explore whether a naturally occurring substance very close in structure to methylxanthine theophylline also had the same antitussive properties. This naturally occurring substance was theobromine—the bitter alkaloid of the cocoa plant, as well as a component found in tealeaves and the kola nut.
To first test whether theobromine has cough suppressive properties, the authors turned to a cough model in guinea pigs. To give the guinea pigs coughs, the scientists microinjected small amounts of citric acid into the larynx of guinea pigs. The larynx is the hollow tube forming an air passage to the lungs from the mouth and holds the vocal cords. Citric acid treatment gives guinea pigs a cough that lasts about 24 hours. When the guinea pigs were treated with theobromine, their coughs were suppressed for 4 hours at a time.
Once they had this preliminary evidence that theobromine acted as an antitussive, the authors examined if it could also inhibit induced coughs in human subjects. The volunteers were first given tablets with theobromine, codeine, or a placebo. Then, they inhaled capsaicin, the active component of chili peppers, which induces coughing. To measure the effectiveness of the cough medicines, the scientists measured the amount of capsaicin needed to induce coughing in the volunteers who had taken one of the three types of pills. The more capsaicin needed to induce coughing, the more effective the medicine is as a cough suppressant. Surprisingly, the volunteers that took theobromine required about one-third more capsaicin to start coughing as the volunteers who took codeine, meaning that theobromine was a more effective at suppressing a coughing reflux than codeine.
Since this discovery in 2004, there have been more reports and clinical trials that have explored theobromine as an alternative cough suppressant to codeine. One study, presented at the British Thoracic Society’s winter meeting in 2012, found that of 300 patients with persistent coughs at 13 hospitals that were given theobromine, 60% found great relief. It has also since been shown the mechanism by which theobromine works: it blocks the sensory nerves that cause coughing, preventing them from inducing the cough reflex.
The coldest weekend of this winter is upon us here on the east coast of the United States and I have a feeling another wave of colds is upon everyone. Thankfully, I have scientific evidence that hot cocoa and chocolate bars can keep me feeling better... or at least suppress my coughing.