Microbiologists at Kansas State University found that adding small amounts of the spice to samples of apple juice contaminated with the E. coli bug killed off almost all the bacteria.

Just one teaspoon of cinnamon killed 99.5% of the bacteria after three days at room temperature.

When the same amount of cinnamon was combined with either of the preservatives sodium benzoate or potassium sorbate E. coli was reduced to an undetectable level.

'Natural killing power'

Unpasteurised fruit juice is a known source of E. coli infection.

Professor Daniel Fung, an expert in food science at Kansas State, said: "Cinnamon contains a compound that has the ability to kill bacteria. It has natural killing power.

"If cinnamon can knock out E.coli 0157:H7, one of the most virulent food-borne microorganisms that exists today, it will certainly have antimicrobial effects on other common food-borne bacteria such as Salmonella and Campylobacter."

Most E.coli bacteria are harmless, but a strain known as E.coli 0157 causes gastroenteritis symptoms such as diarrhoea.

Cases on the increase

It usually clears up after a few days, but complications that may arise include inflammation of the bowel, and anaemia. In some cases, kidney problems may arise.

E.coli 0157 strain is found mainly in the gut of cattle.

An outbreak killed 21 people in central Scotland in 1996 and 1997.

The number of cases in the UK has tripled over the last decade.

Last year, the same researchers added various spices to raw ground beef and sausage. They found that cinnamon, clove and garlic were the most powerful in killing E.coli.

Cinnamon is the scented bark of a tropical evergreen tree, native to India and Sri Lanka.

The inner bark of the tree branches is stripped by scraping off the corky outer layer and dried.