Tuesday, 12 November, 2002, 00:01 GMT

Diabetics who are prepared to wait while their food cooks slowly might protect themselves against dangerous blood vessel problems, suggests research.

Experts from the US say that preparing food using high temperatures increases the levels of potentially toxic chemicals.

And they say that while a healthy person could cope with these chemicals, diabetics are less able to do so.

It's a little early to be telling diabetics to change the way they prepare their food

Professor Alan Stitt, Queen's University Belfast However, a UK expert said it was probably too early to start advising severe diabetics to change their cooking habits.

The chemicals in question are "advanced glycation end products" (AGEs), which are formed when combinations of sugars, proteins and fats - such as those found in many foodstuffs - are heated.

These can also be generated from fats, sugars and proteins circulating in the body.

When certain body tissues are exposed to AGEs over long periods, they can lose their natural elasticity.

The most important example of this is the way the walls of blood vessels can become hardened, allowing the accumulation of fatty plaques which can eventually block the vessel and cause problems.

Diabetic problem

Diabetics are known to be particularly prone to heart disease, and one of the reasons is because uncorrected high blood sugar levels offer more opportunity for the generation of AGEs.

However, it is not yet established whether the source of these AGEs is purely internal, or whether AGEs created during the cooking process can get into the bloodstream and contribute to the process.

To try to answer this question, researchers at Mount Sinai School of Medicine in New York took two small groups of diabetic patients and put both on a diet with the same essential ingredients.

However, one was allowed to cook the food normally, while the other slow-cooked it to avoid the generation of AGEs.

Then all the subjects were given blood tests to check for AGE levels.

Higher levels

Those cooking in a normal fashion had significantly higher levels of AGEs in their bloodstreams than those who took the slow-cooking route.

They also had higher levels of a chemical linked to inflammation of the tissue that makes up the blood vessel wall.

This suggests, say the researchers, that AGE levels in food may have an impact on the levels in the bloodstream.

Professor Alan Stitt, an expert on diabetic vascular problems at Queen's University in Belfast, said that there were still sceptics who believed that AGEs could not get through the gut wall and reach the blood.

He told BBC News Online: "This is one of those ideas that is not widely accepted.

"In my opinion, AGEs do probably have a major role to play - but a lot more work needs to be done to prove this.

"It's a little early to be telling diabetics to change the way they prepare their food."

He said it was likely that severe diabetics with "end-stage" kidney problems would be most disadvantaged by AGEs, as their bodies were less capable of removing excess amounts of this chemical.

The study was published in the journal Proceedings of the National Academy of Sciences.

-- Anonymous, November 11, 2002