The kids are right; eating bread crust might be bad for you. Consumption of dark baked goods and other edibles cooked at high temperatures increases your chance of exposure to acrylamide, a chemical that the National Center for Toxicological Research is studying for its carcinogenic effects.

Acrylamide is formed naturally in certain foods after they’ve been subjected to high levels of heat, said Stephanie Kwisnek, spokeswoman for the U.S. Food and Drug Administration.

“Really, it is found in small doses,” Kwisnek said. “It does not come from food packaging or the environment.” She added that foods such as french fries, dark breads, cereals, coffee and possibly even burnt steak  contain high levels of acrylamide.

“Our studies are confirming what the two previous lifetime cancer studies in rats had shown; that [acrylamide] is a carcinogen in rodents,” said NCTR chemist Dan Doerge. He said the NCTR began studies of acrylamide in 2004 and when a “compound causes tumors in both sexes and in multiple sites in the animals” there is a higher chance it will cause cancer in humans.

Amino acids and sugars are naturally present in all foods and when they are cooked at a high temperature, their shape changes.  These amino acids join together to build proteins and “if you heat up a protein, it has the tendency to denature,” said Nathan Lucas, a graduate student of biochemistry at University of Illinois at Chicago.

Lucas explained that the shape of a protein is very important in determining its function which is why the malformed proteins may be carcinogenic.

“Most carcinogens have the ability to reach a cell and they cause the cell to start proliferating … telling the cell to divide instead of telling the cell to either stay put or die,” Lucas said.

Kwisnek hastened to note, though, that acrylamide has not officially been determined as a carcinogen for humans, and if it had been, more information and warnings would be released to consumers. She said food does not appear to contain enough acrylamide to harm people.

Doerge said acrylamide causes a great deal of worry because “the best estimates are that about a third of all preventable cancer deaths are related to diet.” Nonetheless he said, “sorting out the things that are actually contributing to human cancers from diet has turned out to be quite difficult. There are not a lot of answers in general, let alone specifically for acrylamide.”

The FDA asked the world’s scientific community to continue research and submit its reviews by Nov. 24.

Still, Doerge said, “You can’t stop eating cooked food,” because the benefits of cooking, including the killing of bacteria and the release of aromas and flavors people love, are all too great to switch to eating completely raw food.

“This isn’t an oddball diet” comprised of uncommon foods which are high in acrylamide levels, Doerge said.  The carcinogen is found in a variety of foods that the majority of people eat on a daily basis. Doerge said Americans have a lot of reasons to change their diet though, pointing to the prevalence of salt and fat in what we eat.  But even if everyone avoided all foods high in acrylamide, there wouldn’t be a noticeable change.

Novozymes and DSM Nutritional Products, two chemical companies, each developed an enzyme in 2008 that can work against the formation of acrylamide. Some countries approved Novozymes’ enzyme, Acrylaway, but Doerge said his understanding is that while this approach is somewhat effective, it won’t be much more helpful than avoiding foods with acrylamide.

Acrylamide isn’t the only carcinogen in food that the NCTR is keeping its eye on. Doerge said other common foods contain possible carcinogens. He mentioned benzo[a]pyrene in jarred foods and heterocyclic amine in grilled meat, to name a few among others.

Both Doerge and Kwisnek said the best option is for everyone to continue eating a balanced diet, rich in fruits and vegetables. Doerge said just keep doing what your mother told you all along.

tgleason@chroniclemail.com