Acrylamide: Why french fries shouldn't be overheated

Governments are targeting the naturally occurring chemical in fried starchy foods that has been linked to cancer in lab rats

September 18, 2009|By Julie Deardorff, Tribune reporter






Previously known as a synthetic substance found in plastics, grouts and cigarette smoke, acrylamide exploded on to the food safety scene in 2002 when scientists at the Swedish Food Administration detected surprisingly high levels of it in high-carbohydrate foods and published evidence linking it to cancer in lab rats.

Since then, a worldwide flurry of scientific research has yielded hundreds of published studies. So far, there's little evidence that dietary acrylamide harms humans. But widely anticipated research to be released later this year is expected to confirm that megadoses of the chemical are carcinogenic in laboratory animals -- the usual methodology for toxicological studies.

Before acrylamide was discovered in food, concerns about the chemical's potential health effects centered on workers who handled it as an industrial substance. Now that it's known everyone likely is exposed through diet, scientists want to know how the body handles dietary acrylamide and whether it can cause cancer.

"Everyone realizes acrylamide is in so many foods and at such high levels that we can't just sit back and say, 'ho-hum,'" said food safety consultant James Coughlin, a spokesman for the Institute of Food Technologists. "I've never seen such cooperation between countries, industries and government. [Acrylamide] is the biggest thing going on for food toxicologists."

Unlike some other chemicals of concern, dietary acrylamide doesn't leach from packaging and is not added to food. Instead, it's the product of a chemical reaction that can occur in cooking.

Acrylamide forms when sugars and an amino acid called asparagine are heated together at high temperatures -- more than 248 degrees Fahrenheit. (Boiling occurs at 212 degrees.) This effect, part of what's called the "Maillard reaction," enhances a food's color, flavor, aroma and texture.

Among foods, the highest levels of acrylamide turn up in french fries and potato chips. But it also has been found in baked goods, coffee, cocoa, roasted asparagus and even canned olives.

The amount of dietary acrylamide, measured in parts per billion (ppb), varies widely depending on the manufacturer, the raw materials used and processing conditions, including cooking time. When the U.S. Food and Drug Administration tested seven batches of McDonald's french fries, it found levels ranging from 193 ppb to 497 ppb. One sample of Krispy Kreme Original Glazed Doughnuts had no detectable levels; a second sample showed 22 ppb.

To cut the levels in processed foods, food scientists have reduced the levels of sugars and asparagine in the ingredients. The U.S. food industry discovered an enzyme called asparaginase that can chew up asparagine in food products so less acrylamide is formed.

Food companies also have tried altering raw materials or the way the food is processed, including cutting the heating times and temperatures and changing the oils used or the food's acidity. But what works in the lab "doesn't necessarily work in big food laboratory plants," said Coughlin, an expert on the browning process.

Governments are also taking a closer look. Last month, federal health officials in Canada added acrylamide to their list of chemicals in widespread use to be reviewed for safety. The European Chemicals Agency recently proposed adding acrylamide to its own list in order to possibly regulate its use.

In the U.S., the FDA announced it may issue industry guidelines on how to reduce acrylamide levels in food. The move comes in anticipation of emerging research, including studies conducted at the FDA's lab at the National Center for Toxicological Research.

Though the agency regulates the amount of residual acrylamide in materials that come in contact with food, there are no guidelines governing the presence of acrylamide in food itself.

Instead, the FDA's advice is to eat a healthy, balanced diet that is low in fat, cholesterol, salt and added sugar and rich in high-fiber grains, fruits and vegetables. In other words, consume less fast and processed food.