Janet L. Stanford, Marni Stott-Miller and Marian Neuhouser, all of the Fred Hutchinson Cancer Research Center's Public Health Sciences Division in Seattle, analyzed data from two prior population-based case-control studies involving 1,549 men diagnosed with prostate cancer and 1,492 age-matched healthy controls.
The men were Caucasian and African-American Seattle-area residents ages 35-74. Participants were asked to fill out a dietary questionnaire about their usual food intake, including specific deep-fried foods.
The researchers controlled for factors such as age, race, family history of prostate cancer, body-mass index and screening history when calculating the association between eating deep-fried foods and prostate cancer risk.
"The link between prostate cancer and select deep-fried foods appeared to be limited to the highest level of consumption -- defined in our study as more than once a week -- which suggests that regular consumption of deep-fried foods confers particular risk for developing prostate cancer," Stanford said in a statement.
Deep frying may trigger formation of carcinogens in food. They include acrylamide, found in carbohydrate-rich foods such as French fries, chemicals formed when meat is cooked at high temperatures, aldehyde, an organic compound found in perfume, and acrolein, a chemical found in herbicides.
These toxic compounds are increased with oil re-use and increased length of frying time. Foods cooked with high heat also contain high levels of advanced glycation endproducts, associated with chronic inflammation and oxidative stress. A chicken breast deep fried for 20 minutes contains more than nine times the amount of advanced glycation endproducts as a chicken breast boiled for an hour, Stanford said.
The study, published online in The Prostate, found men who ate one or more of these foods at least weekly had an increased risk of prostate cancer that ranged from 30 percent to 37 percent.