(NaturalNews) According to a new study conducted by researchers from the Netherlands, consuming high levels of acrylamide increases people's risk of kidney cancer by 59 percent,
Kidney cancer is the tenth most common cancer in the world. According to Marji McCullough, a nutritional epidemiologist for the American Cancer Society, smoking and obesity are well-known risk factors for the disease.
"It's best not to smoke and to maintain an ideal body weight," McCullough said. "One way to maintain a healthy body weight is a healthy diet."
But increasing evidence is emerging that dietary factors may also play a role.
Acrylamide is found in coffee and in starchy foods like grains and potatoes that have been baked, fried, roasted or toasted. It has been classified as a probable human carcinogen by the International Agency for Research on Cancer since 1994, due to its documented genotoxic and carcinogenic effects in laboratory animals.
In the most recent study, researchers looked directly at the effects of dietary acrylamide on cancer risk by studying data from the Netherlands Cohort Study on diet and cancer, which includes more than 120,000 adult female and male participants between the ages of 55 and 69. Researchers from Maastricht University, the Dutch Food and Consumer Product Safety Authority, and TNO Quality of Life calculated the dietary acrylamide intake of 5,000 random participants, based on food frequency questionnaires filled out when the cohort study began.
The results are presented in the article "Dietary acrylamide intake and the risk of renal cell, bladder, and prostate cancer" by J.G. Hogervorst, L.J. Schouten, E.J. Konings, R.A. Goldbohm, P.A. van den Brandt, published in the American Journal of Clinical Nutrition (May 2008, Volume 87, Number 5, pp. 1428-1438).
The researchers found that after 13.3 years, those who had the highest dietary acrylamide intake experienced a 59 percent higher risk of renal cell carcinoma than those with the lowest intake. Renal cell carcinoma is responsible for more than 80 percent of kidney cancer cases.
"We found some indications for a positive association between dietary acrylamide and renal cell cancer risk," the researchers wrote.
A total of 339 cases of kidney cancer, 1,210 cases of bladder cancer and 2,246 cases of prostate cancer were observed among study participants. The researchers did not observe any connection between acrylamide intake and cancer of the bladder or prostate.
The highest average acrylamide intake was 40.8 micrograms per day, while the lowest was 9.5 micrograms per day. Average intake was 21.8 micrograms per day, or slightly less than the amount found in a 2.5-ounce serving of French fries. Every 10 microgram increase in daily intake appeared to increase a person's risk of kidney cancer by 10 percent. Among smokers, the effect of dietary intake was even stronger.
Coffee was the biggest source of dietary acrylamide for the study participants. Among participants in the group with the highest average intake, however, the biggest source was a popular baked snack called Dutch spiced cake.
Prior to 2002, acrylamide was known only as an industrial chemical that consumers might be exposed to through cigarette smoke, cosmetics or the breakdown of certain environmental contaminants such as the herbicide glyphosate (Roundup). Then researchers from the Swedish Food Administration discovered that the chemical also formed at high levels in many popular foods, such as potato chips and bread. Since then, research has suggested that it may also form in dried fruit.
Although acrylamide is generally accepted to pose health risks in humans, some researchers have questioned whether typical dietary intakes are actually high enough to have an effect. The recent study is only one of the latest to suggest that dietary intake is indeed a significant source of exposure to the chemical.
In earlier research conducted by the same team of scientists, also using data from the Netherlands Cohort Study, dietary acrylamide was found to increase women's risk of ovarian cancer by 78 percent and their risk of endometrial cancer (in the lining of the uterus) by 29 percent. Among women who had never smoked, the increase in risk was much higher: 122 percent for ovarian cancer and 99 percent for endometrial cancer.
Researcher J.G. Hogervorst recommended that people limit their acrylamide intake, including from their diet.
"In preparing food at home, fry potatoes at temperatures below 175 degrees Celsius [347 degrees Fahrenheit] and fry them to gold-yellow, not dark brown," Hogervorst said. "The same goes for making toast and cookies."
The darker a food is fried or baked, the more acrylamide it contains. Foods that are steamed or boiled do not contain acrylamide.