The team of researchers discovered that theobromine, a derivative found in cocoa, is nearly a third more effective in stopping persistent coughs when compared with codeine, currently considered the best cough medicine.
"While persistent coughing is not necessarily harmful it can have a major impact on quality of life, and this discovery could be a huge step forward in treating this problem," said Professor Peter Barnes, at the Imperial College London and Royal Brompton Hospital, and one of the paper's authors.
Chocolate has recently been in the media spotlight with findings that naturally occurring flavonols, found in cocoa, may improve blood vessel function, believed to be an important indicator of cardiovascular health. The caffeine contained in chocolate is also thought by some to benefit heart health.
For this very small study researchers gave 10 healthy volunteers theobromine, a placebo or codeine at different times in a randomised double blind trial.
In order to compare the effectiveness of each they measured the levels of capsaicin in the volunteers and compared these after giving the three options. Scientists use capsaicin, a chemical compound found chillies used in clinical research to provoke coughing, as an indicator to test the effectiveness of cough medicines.
When the volunteers were given theobromine, the concentration of capsaicin required to produce a cough was around one third higher when compared with the group receiving a placebo.
When the group received codeine they needed only marginally higher levels of capsaicin to produce coughing, compared with the placebo.
Theobromine works by suppressing vagus nerve activity, which is responsible for causing coughing, say the team, that also discovered that unlike standard cough treatments, theobromine caused no adverse effects on either the cardiovascular or central nervous systems.
"Not only did theobromine prove more effective than codeine, at the doses used it was found to have none of the side effects," said Professor Maria Belvisi, from Imperial College London and Royal Brompton Hospital, another of the paper's authors. "With theobromine having no demonstrated side effects in this study it may be possible to give far bigger doses, further increasing its effectiveness."
While it is too early to advise people suffering from coughs to treat themselves with chocolate, Belvisi said that "with theobromine having no demonstrated side effects in this study it may be possible to give far bigger doses, further increasing its effectiveness."
The study was presented in December 2002 at the British Thoracic Society's (BTS) Winter Meeting in London. Full findings have now been published in the FASEB online journal.