They have found the active agent in turmeric, the spice that colours and flavours many Asian meals, can block a cancer-promoting protein.

They want to follow up tests using cell cultures in the laboratory with trials of tablets on patients.

This would involve giving volunteers 500mg tablets of the constituent known as curcumin each day for a week to see whether it inactivates the NF-kappaB protein which plays a key role in Barrett's oesophagus, a pre-cancerous condition, and oesophageal cancer.

The work at Swansea University's school of medicine and the Morriston hospital in the city builds on a growing body of worldwide evidence that turmeric, powder from a plant of the ginger family, can help stave off cancers such as leukaemia, prostate cancer, skin cancer and colon cancer.

A team in America is hoping human trials could help lead to the development of a drug against Alzheimer's disease, while others hope its anti-inflammatory properties might also protect against Crohn's disease.

Lower levels of some similar conditions among people living in Asia first sparked the interest in investigating whether curry has protective properties. Barrett's oesophagus is a condition in which long-standing inflammation of the gullet leads to changes in the cells lining the gullet. In about 10% of cases, this can lead to cancer.

The Swansea team, which has previously found that increased NF-kappaB has helped tumour cells develop in several cancers of the gastro-intestinal tract, have been investigating how different substances with reputed anti-cancer properties deal with the protein.

Resveratrol, a chemical in red wine which a recent Spanish study suggested helped drinkers reduce their chances of getting lung cancer, also blocked the protein, as did vitamin C and a chemical from green tea.

Vitamin E and a chemical found in broccoli were far less successful.

But rushing to the curry-house and washing the meal down with wine, will not be the way forward, says Gareth Jenkins, a lead researcher in the project.

Despite the fact that a number of spicy foods have recently also been found to contain illegal and potentially cancerous ingredients such as Sudan 1 and Para Red, too much drinking increases the risk of gullet cancer.

"We are looking at the activity of just one protein, it is only one part of the whole cancer development process," said Dr Jenkins. "You would not want to encourage people to eat a takeaway every day to get the curcumin because they may die of heart disease."

Indian food contained a lot of fat, he said. Developing supplements taken in tablet form or adding turmeric to less fatty foods would be better.

That all remains some way off. For now, the researchers hope they can win ethical permission for a pilot study in humans.

This would involve some volunteers with Barrett's oesophagus having curcumin tablets and other dummy treatments a week before they underwent an endoscopy.

Their tissues would then be tested for NF-kappaB activity. Laboratory tests have suggested 24-hour treatment of cells with curcumin almost totally blocks the protein.

But even this study might take two years because the researchers did not want to subject patients to more endoscopies than their condition merited.

"All these patients will have completely different diets, they will be taking different drugs.

"No one really knows why only 10% get cancer," said Dr Jenkins.

Other research teams investigating potential benefits of turmeric have looked at diet of different populations and conducted tests on animals.

But there are no satisfactory animal models for oesophageal cancer, according to Dr Jenkins.

Professor John Baxter, another of the Swansea research team, said: "The curcumin discovery is a shot in the arm for our research." 

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