Mar. 23 -- TUESDAY, Aug. 21 (HealthDay News) -- There seems to be little or no link between breast cancer and acrylamide, a substance found in many baked and fried foods, according to the largest epidemiological study on the subject conducted to date.
"The data are accumulating, and it appears that acrylamide in the diet does not appear to be an important breast cancer risk factor," said study author Lorelei Mucci, an assistant professor of medicine at Harvard Medical School and an assistant professor of epidemiology at Harvard School of Public Health in Boston.
"We probably couldn't rule out that eating very high levels of acrylamide is associated with a very, very small increase in risk, but in terms of it being an important public health risk factor for breast cancer I don't think acrylamide is a major risk factor," she said.
Mucci plans to present the finding Tuesday at the American Chemical Society annual meeting, in Boston. The paper is one of 40 exploring various facets of a possible association between acrylamide and cancer.
Acrylamide is classified as a "probable" human carcinogen but only based on earlier animal studies in which the animals were exposed to levels of acrylamide up to 100,000 times higher than that normally consumed through foods.
The substance forms naturally during the cooking process of mostly carbohydrate-rich foods such as potato chips, french fries, breads, cereals and even coffee.
Even though the data on human health has remained unclear, food safety authorities in Europe have started to curb acrylamide in foods.
According to the study authors, about 30 percent of calories consumed among U.S. and European populations contain acrylamide. The average adult consumption is 0.5 micrograms per kilogram of body weight per day. Children consume higher levels.
For the current study, Mucci and her colleagues followed a group of 100,000 U.S. nurses over a 20-year period. Participants periodically answered questionnaires about their dietary habits. This information was used to estimate daily acrylamide intake, which was then correlated with breast cancer incidence.
The result: The incidence of breast cancer among women with a high acrylamide intake was about the same as women with low intakes.
That corresponds with findings from a previous study (also by Mucci) of Swedish women that also showed no association between dietary acrylamide and risk of breast cancer. The largest source of dietary acrylamide in U.S. women is french fries, while in Swedish women it is coffee.
The only other published epidemiological study, conducted in Italy, also found no association.
"At the moment, I don't think there is any clear connection between acrylamide and breast cancer," said Shiuan Chen, director and professor of surgical research at City of Hope Cancer Center in Duarte, Calif.
"I thought the results were gratifying," added Robert Tardiff, president of the Sapphire Group and an advisor to the Food Products Association, both in Washington, D.C.
"Here is an example of a situation which caused a great deal of concern based on laboratory studies, and now we have a reasonably definitive study showing that there's no link between acrylamide consumption and breast cancer. So, that's great," he said.
The association found in animal studies could be explained by the high levels of acrylamide they consumed, or by differences in how acrylamide is metabolized in the body, the experts said.
This is not likely to close the door on research into acrylamide, however.
"The food industry has been spending a lot of time and research on how to avoid acrylamide formation in food, and toxicologists are still very interested in looking at acrylamide," Mucci said. "There's also a new animal study with rats and mice looking at very high levels of acrylamide and cancer risk. There's been concern whether acrylamide could have some impact on hormonal levels, so we would want to look at endometrial and ovarian cancer, because they are hormone-driven."
Tardiff added, "One of the issues that we are working on, and that we think is particularly promising, is that there is significant detoxification of acrylamide quickly [in the human body], so it is no longer available at the levels we found in food. That research will be finished in the next couple of months."
Mucci will also be presenting data at the American Chemical Society meeting on prostate cancer and acrylamide (again, her team found no link).
But cancer is not the only reason to avoid certain foods.
"We want to think about our overall health, and there are a lot of reasons to have a low-fat diet and maintain a healthy weight," Mucci pointed out. "Obesity is a risk factor for so many diseases. Eat a sensible diet, don't eat too much of one thing. If you get a diverse diet, you're probably going to be protecting yourself."
"Environmental exposures have a lot of influence on cancer, including breast cancer, and that includes diet," Chen added. "Diversify your diet. Eating french fries once in a while is probably OK, but not three times a day."
The Joint Institute for Food Safety and Applied Nutrition has information on acrylamide.
SOURCES: Lorelei Mucci, Sc.D., assistant professor, medicine, Harvard Medical School and assistant professor, epidemiology, Harvard School of Public Health, Boston; Shiuan Chen, Ph.D., director and professor, department of surgical research, City of Hope Cancer Center, Duarte, Calif.; Robert Tardiff, Ph.D., president, Sapphire Group, and advisor, Food Products Association, Washington, D.C.; Aug. 21, 2007, presentation, American Chemical Society annual meeting, Boston