Sucrose, Mint Help Suppress Coughing

PHILADELPHIASucrose and menthol, ingredients commonly regarded as flavorings in cough remedies, each act independently to reduce coughing, according to a new study published in the journal Pulmonary Pharmacology and Therapeutics

Researchers at the Monell Chemical Senses Center conducted a study to investigate how chemicals act to trigger and modulate cough. For the study, 12 healthy young adults inhaled from a nebulizer containing capsaicin, the burning ingredient in chili peppers and a potent chemical stimulus for cough. After each inhalation, the amount of capsaicin was doubled. The procedure continued until the subject coughed three times within 10 seconds. The capsaicin concentration that induced the three coughs was labeled as the individuals cough threshold.

In some sessions, the subjects held either a very sweet sucrose or plain water in their mouths for three seconds, spat the liquid into a sink, and then inhaled from the nebulizer. In other sessions, subjects inhaled three breaths of either menthol-saturated air or clean air before each capsaicin inhalation. The menthol concentration was selected to approximate the cooling intensity of a menthol cigarette.

Both sucrose and menthol increased the amount of capsaicin needed to elicit a cough relative to plain water or clean air, respectively. Sucrose increased cough threshold by about 45%, while menthol increased it by approximately 25%.

This is the first study to empirically show that sweet taste reduces cough. This also is the first study to show that menthol alone can reduce coughing in response to a cough-eliciting agent," said Monell sensory scientist Paul Breslin, Ph.D., an author on the study.

The findings support the hypothesis that adding menthol to cigarettes, popularly known as menthols," may make it easier to begin smoking by suppressing the cough reflex, thus making the first cigarettes less distressing. Menthol may dull the sensitivity of sensory nerves in the airways and thereby actually disable an important reflex mechanism that would otherwise protect smokers from the chemical and particulate irritants present in cigarette smoke," Wise said.