The gum -- known as mastic gum -- comes from the resin of the Pistacia lentiscus tree which, when dried, becomes solid but chewable with a pleasant taste. It has long been used as a food additive for flavoring. Patients are being prescribed the gum daily for two weeks to get rid of the organism responsible for the ulcers -- helicobacter pylori. They will get 2g a day and have levels of the bug measured five weeks later.

Millions worldwide suffer from peptic ulcers, and the organism can become resistant to standard antibiotics, requiring new, more expensive drugs. The clinical trial in Greece, involving 42 patients, comes after research at Nottingham University showed that the gum is effective even in tiny doses.