Cold left-overs ward off cancer

Scientists have discovered that indigestible crystalline starch found in these types of types of cold food may have a protective effect.

For years, people have been told that eating a high-fibre diet can reduce their chances of getting bowel cancer.

But a leading scientist claims that this is a misconception based on the fact that bowel cancer rates are low in Africa, where fibre makes up a high proportion of the local diet.

Professor John Burn, speaking at the British Association's science festival in Leicester, said the real key was the high level of crystalline starch found in staple foods such as yam and casava.

Reaction

Laboratory tests have shown that this form of carbohydrate interacts with the bacteria in the lower gut to produce a chemical that effects the function of genes known to be linked to bowel cancer.

However, Professor Burn said the food had to be eaten cold to have an effect.

Heating it up changes the chemical structure, and renders it useless as an anti-cancer agent.

Professor Burn said: "I'm talking about anything that contains carbohydrate that's not hot. Hot food will by and large be less good."

He said the belief that high-fibre diets helped prevent bowel cancer was an example of experts jumping the gun and making wrong assumptions.

"The fact is we went off running down that route without the evidence, but it was a wild goose chase," he said. "Most high-fibre diets are also high carbohydrate diets."

Aspirin effect

Professor Burn is also investigating the effect of aspirin on bowel cancer.

Early research findings and anecdotal evidence suggested that the pain killer, derived from the willow tree, could combat the disease.

This may be linked to substances called salicylicates which plants use to protect themselves against disease by inducing controlled cell death.

Modern diets missed out on these substances, because cultivated plants were not allowed to get infections and therefore did not produce salicylicates.

Professor Burn is heading a study funded by Cancer Research UK to see whether aspirin or indigestible starch powder can help people with an inherited vulnerability to cancer.

The aim is to recruit 1,000 volunteers, most of whom will be susceptible to bowel cancer. So far 500 people have been recruited from 33 centres around the world.