The Telegraph
Since 1st March, 1999
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It’s not what you eat, but how you fry or microwave it

Washington, Nov. 12 (Reuters): It may not be what you eat, but how you cook it, that affects whether food causes heart disease, diabetes and other conditions, researchers in the United States reported today.

A new study shows that cooking at high temperatures — frying, grilling and even microwaving — creates compounds that are associated with disease when they are found in the body.

Foods cooked by low-temperature methods such as boiling and steaming do not contain as many of these compounds, the team at the Mount Sinai School of Medicine in New York found.

While the findings do not discount the benefits of a healthy diet low in fat and sugar, they may help explain why some people who stick to such a diet continue to suffer from heart disease and diabetes, Dr Helen Vlassara, who led the study, said in a telephone interview.

The culprits are called advanced glycation end products or AGEs for short.

They are made by the interactions of sugars, fats, and proteins and form quickly when food is cooked at high temperatures.

“These are substances that are forming spontaneously in our body from glucose reactions,” Vlassara said.

“The higher the glucose is, the higher the products will be. Diabetics have a lot more, and they are highly toxic.”

Writing in the Proceedings of the National Academy of Sciences, Vlassara and colleagues said AGEs can irritate cells, causing them to produce proteins that trigger inflammation, such as C-reactive protein.

“We tend always to cook our food under high heat. And because most foods consist of proteins, lipids and sugars, when we heat them under high heat for a long time, those reactions are accelerated. We end up absorbing those,” she said.

Tasty and brown

This kind of cooking produces tasty foods, Vlassara said. “They make the food taste good, or make it look good — by browning it,” she said.

Animal products rich in fat are the worst culprits, she said.

Her team studied 24 diabetes patients, giving them identical diets that differed only in how the food was prepared.

“The diets that we tested and gave to patients in this report are those that are recommended for diabetics,” Vlassara, a specialist in diabetes, said.

But where one group got grilled tuna, another got poached tuna, for example. The poached tuna would presumably be lower in AGEs as it was cooked at lower temperatures.

There were clear differences in the blood of the patients, although it was too soon to tell whether there were health benefits, Vlassara said.

Those eating the high AGE diet had more AGEs in their blood, and also had higher levels of inflammatory chemicals such as tumor necrosis factor and C-reactive protein.

These inflammatory chemicals are linked with the progression of heart disease and the damage caused by diabetes — such as blindness, nerve damage, and damage to organs such as the kidney.

In other studies on animals, Vlassara said a low-AGE diet helped prevent the development of type-I diabetes, caused when the body mistakenly attacks and destroys the pancreatic cells that make insulin.

Vlassara said she did not believe her findings related to the discovery this year that some fried and baked foods contain high levels of chemicals called acrylamides, which can cause cancer in animals.

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