MONDAY, March 29, 2004 (HealthDayNews) -- Ever since unexpectedly high levels of acrylamide were found in some popular baked and fried foods in 2002, scientists have been trying to determine how dangerous the chemical is to humans -- if at all.
Acrylamide, which forms when certain carbohydrate-rich foods such as potato chips and french fries are cooked at high temperatures, is classified as a possible human carcinogen. According to the U.S. Food and Drug Administration, the substance is known to cause cancer and reproductive problems in animals, and in humans it is a neurotoxin at high enough doses.
Yet few studies have looked at acrylamide's actual impact on human health. This week, the American Chemical Society is hosting a three-day symposium during its annual meeting in California that features data from the most recent research.
On the whole, there seems to be little evidence to support a link between acrylamide and human cancers, such as tumors of the colon, rectum, bladder and liver.
Lorelei Mucci, an instructor in medicine at Harvard Medical School, and her colleagues have conducted four studies assessing the health impact of acrylamide in Swedish populations. She is presenting them at the meeting, which ends April 1. Two of the studies have already been published.
The first of the published studies found no evidence of a higher risk of colon, rectum and bladder cancer as a result of consuming acrylamide.
The second published study found no link between acrylamide and kidney cancer. "We found absolutely no association between higher intake of acrylamide and risk of renal cancer," Mucci says.
"The mean intake of acrylamide in all of our studies was between 25 and 35 micrograms per day," she says. Current risk assessment says acrylamide might start increasing the risk of cancer at about one microgram per kilogram of body weight. For an average person (70 kilograms), that would mean 70 micrograms per day. "The mean was half that," Mucci points out.
The first of the unpublished studies, a cohort of 60,000 Swedish women followed for 12 years, again found no difference in dietary acrylamide between the women who developed colon or rectal cancer and those who didn't. The data are preliminary, however, and the authors aren't drawing any conclusions about acrylamide and the risk of cancer.
The second unpublished study followed a different group of 49,000 Swedish women for 11 years and found the mean intake of acrylamide per day was about 31 micrograms in both the group that developed breast cancer and the group that didn't. Again, no conclusions are being drawn.
"Nobody knows what the bioavailability [of acrylamide] is, how your body uses it, so you could be exposed to perhaps 100 micrograms but maybe the body flushes it out," Mucci says. "That's an important question, too."
Overall, epidemiologists are coming to believe that levels of acrylamide within the average diet are probably not increasing the risk of human cancer, Mucci says. "What epidemiology cannot do is detect a really, really small effect and we can never really prove that something doesn't cause risk," she says.
Despite the lack of proof of risk, scientists are already working on alternatives to acrylamide. Some researchers may have found a way to short-circuit the formation of acrylamide during the cooking process.
"What we found out is that acrylamide is formed from the reaction of an amino acid [asparagine] that is present in all foods," says David Zyzak, a senior scientist at Procter & Gamble in Cincinnati. The amino acid reacts with sugars such as glucose and fructose during the cooking process and results in a small amount of acrylamide.
A different enzyme, asparaginase, degrades asparagine so it doesn't form acrylamide. "We took potato byproducts and treated them with asparaginase and saw that we can get a greater-than-90-percent reduction in acrylamide," Zyzak says.
Asparaginase is used in the treatment of leukemia patients. It is not a food-grade enzyme and therefore can't be incorporated into food yet. "We're working with another company trying to develop an asparaginase that could potentially be food-grade, but we would have to get [FDA] approval," Zyzak explains. "It is potentially a solution, but it could not be acted upon tomorrow."
On March 25, the FDA released new data on acrylamide levels in more than 750 new food samples, including black olives, prune juice and Postum, a powdered beverage.
In the absence of definitive health-risk information, the agency is advising consumers to eat a "balanced diet" with a "variety of foods" low in fat and high in grains, fruits and vegetables.
Mucci concurs.
"A lot of the foods [with acrylamide] have high levels of fat and we shouldn't be eating them anyway," she says. "There's an increased risk of obesity and cardiovascular disease, and we know those are major public health problems. Your risk of cancer may be small but your risk of these other things is big and it's not because of the acrylamide."
More information
The FDA has more on acrylamide in food, along with the new sampling data. The Joint Institute for Food Safety and Applied Nutrition also has information on acrylamide.
