Theobromine, a compound in chocolate, works as effective cough medicine

Researchers in the UK gave 10 healthy volunteers tablets which contained either theobromine, found in cocoa, codeine, the cough suppressant, or a placebo. The volunteers were told to inhale a gas containing capsaicin, a derivative of chili peppers, which induces coughing. The volunteers who took theobromine needed one third more capsules to produce coughing than those who took codeine.

Theobromine, which has no side effects, acts on the sensory nerve endings at the vagus nerve, which runs through the airways in the lungs to the brain. Codeine was shown to be only marginally more effective than the placebo.

• An ingredient in chocolate may actually be a more effective cough medicine than traditional remedies, a new study suggests.
• And not only that, the UK-based research showed that the cocoa-derived compound had none of the side effects associated with standard drug treatments for persistent coughs.
• "These sorts of coughs, often lasting for weeks after a viral infection, can be difficult to treat, especially since it is not possible to give large doses of opiate-based medication to patients due to the side effects," says Peter Barnes, professor of thoracic medicine at Imperial College London, UK, who led the study.
• Barnes and colleagues gave 10 healthy volunteers tablets containing: theobromine, a constituent of cocoa or; codeine, the cough suppressant against which other drugs are measured or; a placebo.
• The volunteers were then asked to inhale a gas containing capsaicin - a derivative of chilli peppers - which induces coughing and is used as an indicator to test the effectiveness of cough medicines.
• Dame Helena Shovelton, chief executive of the British Lung Foundation, says: "The results of this research sound very promising.
• Persistent coughing often affects lung disease patients so this could be a progressive step in treating it."
• But she advises that "patients to speak to their family doctor before changing their medication or treating their cough with chocolate", as tempting as that may be.
• This is not true of codeine, which is a narcotic and lists drowsiness and constipation among its negative effects.
• The researchers believe theobromine acts on the sensory nerve endings of the vagus nerve, which runs through the airways in the lungs to the brain.
• The team explored their hypothesis by looking at theobromine's action on the vagus nerve in separate experiments involving guinea pigs and excised human trachea tissue.