Browned Foods Found to Pose Risk for Diabetics

The Pleasure Police who try to deny us life’s fleeting moments of joy have found one more category of food that is not good for at least some of us--deliciously browned meats and pastries.

We already knew that the charbroiled steak smothered in barbecue sauce, the golden-brown Christmas turkey glazed with honey and the richly browned cinnamon roll are not particularly good for us because of their calories and fat, but a new study suggests they represent a particular hazard to diabetics.

These foods contain a high concentration of a toxic material called advanced glycated end products, or AGEs. AGEs produced naturally in the body are thought to be prime contributors to the deadly complications of diabetes, but no one had ever looked at their role in the diet.

That was a serious oversight, said Dr. Helen Vlassara of the Picower Institute for Medical Research in Manhasset, N.Y., Sunday at a San Francisco meeting of the American Diabetes Assn. The AGEs in a meal containing browned foods are quickly absorbed by the body and can double or triple the concentration of AGEs in the bloodstream.

The dietary chemicals are a particular risk in people who already have diabetic kidney damage, which prevents the body from clearing them rapidly, she added.

“All the delicious little tricks that make food taste good may, in fact, be very toxic,” Vlassara said.

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“That’s a very interesting finding that I hadn’t thought of before,” said Dr. Philip Carey of the Washington University School of Medicine, president-elect of the American Diabetes Assn. Without more studies, “it is very difficult to estimate the magnitude of risk,” he said, but it could be a significant problem if people are adding to their total burden of AGEs through their diet.

Diabetes affects 15 million people in the United States. Nearly 1 million of those have Type 1, or insulin-dependent, diabetes that requires daily insulin injections, while the remainder have Type 2, or adult-onset diabetes, which can usually be controlled with diet, exercise and drugs.

The high blood sugar levels associated with diabetes produce a broad spectrum of complications, including blindness, nerve damage, heart disease and kidney damage. More than 160,000 people die from these complications each year, making diabetes the fourth-leading cause of death by disease in the United States.

There is a growing body of evidence, Carey noted, that many of these complications are caused by AGEs. The molecules are formed when proteins in cells and the blood combine with sugars. This process occurs at a low rate in all people and may be part of the aging process, but it is accelerated in diabetics because of the high sugar levels in their bloodstreams. Diabetics typically have two to three times the normal level of AGEs in their blood.

AGEs are sticky, kind of like a molecular glue. They glom onto the insides of blood vessels, stiffening the arteries and leading to the formation of plaque and clots. In organs like the kidney, they clog up the tiny pores that normally remove wastes from the blood.

AGEs have also been known for a long time to occur in many cooked foods when sugars and protein are heated together. This browning process, known formally as the Maillard reaction, produces AGEs, but they were not believed to be toxic, to be absorbed into the bloodstream or to have any biological effect other than imparting flavor and color.

But no one has ever looked to see if they are a problem, Vlassara said.

Vlassara and her colleagues studied five healthy individuals and eight diabetics using newly developed techniques that allow them to measure the concentration of AGEs in blood and urine. They fed them a meal of meringue--baked egg whites (protein) and sugar--and monitored AGE levels for three days.

Vlassara told the San Francisco meeting that the meringue, which contained the amount of AGEs that might be found in a turkey dinner, doubled or tripled the level of AGEs in the diabetics’ bloodstream, indicating that the food was adding to the body’s burden of the toxins.

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In both healthy and diabetic people, about 30% of the AGEs were cleared out of the body through urine, indicating that a significant proportion stayed behind--perhaps on the walls of blood vessels. In diabetics with kidney damage, however, less than 5% was excreted, suggesting that the food was more dangerous to them.

“I think this is a very important finding that should stimulate more work into modifying the diet and making this population group more aware of the hazards,” Vlassara said. “It is very likely that in the near future we will be able to provide proper dietary guidelines.”

For the time being, however, she suggested that people should avoid mixing foods and sugars and cooking them at high temperatures, citing, in particular, baked pastas and baked goods in general. “Microwaving and steaming foods are much better for you,” she said.