Cooking Carcinogens

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In April of this year researchers in Sweden discovered a potential cancer-causing substance, acrylamide, was produced in large amounts whenever starchy foods such as grains or potatoes are cooked at high temperatures. The Environmental Protection Agency (EPA) limits the amount of acrylamide in drinking water to no more than 0.12 mcg in an 8oz glass. Table 1 on page 101 shows the amount of acrylamide these Swedish researchers and others have found in various foods. Obviously the amount of acrylamide found in these (and no doubt many other foods yet to be tested) is far in excess of the amount of acrylamide the EPA currently allows in drinking water.

Where are they found?

In general, it appears that the acrylamide content increases as a result of:

• Longer cooking time

• Higher cooking temperatures

• More browning

• Greater surface area. Frying, baking, and toasting of starchy foods can be assumed to produce fairly large amounts acrylamide.

By contrast, cooking these same starchy foods by boiling, steaming or in a microwave oven does not appear to produce detectable amounts of acrylamide. In general, dry cereals have much more acrylamide than do whole-grain, hot, cooked cereals (unless toasted). A boiled potato would have little or no acrylamide. A baked potato would have a small amount, but French fries, potato chips, Pringles® and “fat-free” baked potato chips would all be expected to have large to very large amounts of acrylamide.1 Bread has some acrylamide (almost all in the crust) whereas crackers, pretzels and toast have quite a bit more.

Other carcinogens found in meat

It should be noted that fatty foods and meats cooked at high temperatures also yield known and suspected carcinogens. For example, meat, fish and poultry cooked at high temperatures contain a group of known and suspected carcinogens called heterocyclic amines (HCAs). As with the starchy foods, the carcinogens form only when the temperature is high and the meat is browning or charring as would occur with roasting, broiling, frying and grilling. Already some research suggests that these HCAs (or perhaps some other carcinogen produced when meats are cooked at high temperatures) may increase the risk of at least some human cancers. For example, women who preferred their meat well done were found to be more likely to develop breast cancer in one study.2 Poached salmon would have far fewer HCAs and other carcinogens than would blackened salmon. Cured meats (e.g., hot dogs, sausages, bologna) contain nitrites that can form another class of suspected human carcinogens called nitrosamines. When fats and oils burn and smoke is formed it is known that this smoke contains benzopyrene and other known and suspected hydrocarbon carcinogens. Acrylamide, benzopyrene and other suspected human carcinogens have been found in tobacco smoke.

Bottom Line:

While cooking foods at high temperatures produces some of the same carcinogens as found in tobacco smoke, far more research is needed to determine what role these chemicals play in promoting cancer. Most foods high in acrylamide are high in calorie density with a low satiety value so they are not a good choice anyway for those trying to control their weight.

Restricting calorie intake in animals can dramatically reduce the risk of cancer. Both overweight and obese people are at higher risk for developing cancer. Many natural foods (particularly vegetables and fruits) contain nutrients and other substances that appear to protect us from developing cancer.

A diet high in fruits, vegetables, whole grains, beans and moderate amounts of seafood seems most likely to reduce the risk of cancer. It seems prudent until more research is done to caution people at high risk for cancer to limit their exposure to carcinogens. This means limiting the intake of animal products and starchy foods that were cooked at high temperatures to the point where they are browned and crispy.

Practical Tips to Reduce Carcinogens in Food

• Don’t burn or char your food, especially if you are cooking meat or starchy foods.

• Use the microwave or steamer more often in place of the broiler or oven.

• If you enjoy grilled meat, it is a good idea to trim outside fat and to marinate it first so you lessen the chance of having it become charred. Use foil on the barbecue grill to avoid the smoke and flareups from dripping fat.

• Eat smaller portions of meat and larger portions of vegetables, whole grains, beans (legumes) and fruit.

• Limit your consumption of French fries, fried foods, potato chips, crackers and other packaged snack foods.

• Eat more cooked cereals such as oatmeal or cracked wheat instead of relying so much on dry, packaged cereals.

• When preparing bread, toast it lightly or not at all.

• Eat more whole cooked grains such as brown rice, barley, quinoa, pasta and oatmeal instead of relying so heavily on breads and crackers for your grain intake.

• Leave the skin on the chicken breast for cooking and then remove it before eating.

• When cooking on top of your stove, take care that you do not allow fat or oil to smoke before pan-frying or sautéing.

By James J. Kenney, PhD, RD, LD, FACN.

 

References:

1. Nutrition Action Health Letter; September 2002

2 J Nat Cancer Inst. 1998;90:1724

 

 

 

 

 

 

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