It has been just over a decade since Swedish scientists first raised concerns about acrylamide in the food supply after they detected this suspected carcinogen in starchy foods that had been heated to high temperatures. Acrylamide forms during frying, grilling, baking, roasting and toasting, when the amino acid asparagine (for example, in potatoes and grains) reacts with naturally occurring sugars—in something you may remember from high school chemistry class called the Maillard reaction, which gives the foods their brown color, crusty texture and distinctive taste.
Accounting for acrylamide
Studies, including one last year in Food and Chemical Toxicology, have consistently found that potato chips, French fries and other fried potato products have the most acrylamide. (The darker the color, the more acrylamide.) But the chemical is also detected at lower levels in some healthier foods—namely breakfast cereals, crackers and bread, which we tend to eat a lot of. In fact, because of frequent intake of breakfast cereals, a diet that follows government recommendations for healthy eating can end up having higher levels of acrylamide than an unhealthier diet that includes French fries and chips, according to a 2012 study from the University of California, Davis.
Over the years, scientists have also found acrylamide in roasted nuts, peanut butter, olives, some dried fruit, coffee (especially dark-roast brews and instant coffee) and other foods. By one estimate, 38 percent of calories in the U.S. come from acrylamide-containing foods. Nonfood sources include cigarette smoke and, to a much lesser extent, drinking water. (Among other industrial uses, acrylamide is added to drinking water as a clarifying agent—some may remain as a contaminant, though levels are regulated by the Environmental Protection Agency (EPA).
How risky is acrylamide?
The World Health Organization, the U.S. National Toxicology Program and the International Agency for Research on Cancer have all deemed acrylamide a likely or probable human carcinogen, based on animal studies. And it’s a known neurotoxin at high occupational exposures.
But studies on acrylamide and cancer in people have had mixed results, with some showing no increased risk in people with the highest dietary intakes, and others even suggesting reduced risk of colon cancer. Some studies have linked acrylamide to endometrial, ovarian and kidney cancer, for example, but not to bladder, breast or prostate cancer. According to a review in the Annals of Oncology in 2011, research overall does not suggest an increased risk for cancer, with the possible exception of kidney cancer.
A well-designed study in the American Journal of Clinical Nutrition in 2009 found increased inflammation and other risk factors for heart disease in people who ate potato chips (averaging five ounces a day), though other substances in the chips may have been at least partly to blame. More recently, two studies in Environmental Health Perspectives suggested that acrylamide might adversely affect fetal development. In one, higher dietary acrylamide intake in pregnant women, which correlated with blood acrylamide levels, was linked to a reduction in fetal growth. The other linked higher acrylamide exposure during pregnancy to modestly reduced birth weight. The researchers concluded that “reducing dietary acrylamide intake among pregnant women might be beneficial for fetal growth.”
Acrylamide’s potential health risks are hard to study, however. Most of the data come from population studies, in which people report what they have been eating—a notoriously inexact method. Plus, acrylamide levels vary tremendously within the same types of foods, not only from brand to brand, but even from batch to batch, so it’s not possible to determine the exact amounts people consume. The level depends on the crop variety, time of harvest and how the foods are stored, processed, and cooked, among other factors.
In any case, since acrylamide is so prevalent in the food supply, there’s not much difference between low-intake and high-intake groups in observational studies (perhaps if there were, any potential risks would be easier to detect). Lastly, though studies that use blood markers of acrylamide provide a more reliable measure of exposure, they can’t distinguish between food and nonfood sources.
What industry is doing to reduce acrylamide
Taking the issue seriously, the food industry has been devising strategies to reduce acrylamide—for example, by altering cooking times, temperature and methods and by using ingredients such as citric acid salts, ascorbic acid, lactic acid bacteria, calcium, enzymes and antioxidants to help block the formation of acrylamide. Scientists are also looking at ways to alter plants to reduce the compounds that lead to greater acrylamide formation. No single step can lower acrylamide across all foods, however, and reducing it often affects food quality and can increase costs.
Both the Food and Drug Administration (FDA) and European authorities are monitoring acrylamide in foods, but whether levels are going down because of industry efforts, as some companies have claimed, is not yet clear. The most recent European report found an overall decrease in only a few food categories—and increases in others—between 2007 and 2010. Moreover, according to assessments by an international scientific expert committee, dietary intake of acrylamide did not change between 2005 and 2010.
What you can do about acrylamide
More research is needed to determine whether acrylamide, at amounts typically consumed, is a health hazard. Still, lowering your intake is good advice, especially for pregnant women, infants and children, who may be especially vulnerable to the chemical’s effects. You can accomplish this simply by limiting French fries, chips, cookies, pastries, biscuits and pies, which tend to have the most acrylamide—and, of course, are also high in fat, calories and/or sodium.
If you want to fry or roast potatoes, do so only until they are golden yellow, not browned. The same goes for toasting your bread—don’t char or burn it. And if you’re a coffee drinker, you might want to opt for lightly roasted coffee beans in place of darker ones and limit or avoid instant coffees. There’s no reason to give up cereal or other high-carbohydrate foods, but do choose ones made from whole grains, since their nutrients, fiber and phytochemicals may help protect against cancer and other diseases.
Other steps that lower acrylamide exposure include washing and soaking potatoes before cooking; baking them at a lower temperature (250°F/120°C); and not storing them in the refrigerator or in the cold (the compounds that contribute to acrylamide formation increase at temperatures below 46°F/8°C).
Putting acrylamide in perspective
Unless you’re on a raw-foods diet, it’s nearly impossible to avoid all acrylamide—and there’s no reason to, anyway. Since the invention of cooking thousands of years ago, humans have been consuming acrylamide, along with other potentially risky high-heat byproducts, such as heterocyclic amines (see box). Remember, too, that most foods naturally contain potential cancer promoters, as well as cancer fighters. Coffee, for example, is a big source of acrylamide exposure, yet studies consistently find that coffee has health benefits. And if an acrylamide-containing food is otherwise good for you—such as whole-grain breads and whole-grain breakfast cereals—the benefits outweigh the risks. You’re better off focusing on known ways to reduce the risk of cancer—in particular, by not smoking. You would get much more acrylamide from smoking than from food.
Grilling and other methods that expose meat to very high temperatures create potentially cancer-causing compounds called heterocyclic amines (HCAs). When fat drips on the heat source, plumes of smoke can coat meat with other dangerous chemicals.