USC (US) — Cooking red meat at high temperatures, especially pan-frying, may increase the risk of advanced prostate cancer by as much as 40 percent.
Previous studies have emphasized an association between diets high in red meat and risk of prostate cancer, but evidence is limited. Attention to cooking methods of red meat, however, shows the risk of prostate cancer may be a result of potent chemical carcinogens formed when meats are cooked at high temperatures.
For a new study, published online in the journal Carcinogenesis, researchers examined pooled data from nearly 2,000 men who participated in the California Collaborative Prostate Cancer Study, a multiethnic, case-control study conducted in the San Francisco Bay Area.
Participants completed a comprehensive questionnaire that evaluated amount and type of meat intake, including poultry and processed red meat. Information regarding cooking practices (e.g., pan-frying, oven-broiling, and grilling) was obtained using color photographs that displayed the level of doneness. More than 1,000 of the men included in the study were diagnosed with advanced prostate cancer.
“We found that men who ate more than 1.5 servings of pan-fried red meat per week increased their risk of advanced prostate cancer by 30 percent,” says Mariana Stern, associate professor of preventive medicine at the Keck School of Medicine of University of Southern California.
“In addition, men who ate more than 2.5 servings of red meat cooked at high temperatures were 40 percent more likely to have advanced prostate cancer.”
When considering specific types of red meats, hamburgers—but not steak—were linked to an increased risk of prostate cancer, especially among Hispanic men.
“We speculate that these findings are a result of different levels of carcinogen accumulation found in hamburgers, given that they can attain higher internal and external temperatures faster than steak,” Stern says.
Researchers also found that men with diets high in baked poultry had a lower risk of advanced prostate cancer, while consumption of pan-fried poultry was associated with increased risk.
Pan-frying, regardless of meat type, consistently leads to an increased risk of prostate cancer. The same pattern was evident in Stern’s previous research, which found that fish cooked at high temperatures, particularly pan-fried, increased the risk of prostate cancer.
The researchers do not know why pan-frying poses a higher risk for prostate cancer, but they suspect it is due to the formation of the DNA-damaging carcinogens—heterocyclic amines (HCAs)—during the cooking of red meat and poultry.
HCAs are formed when sugars and amino acids are cooked at higher temperatures for longer periods of time. Other carcinogens, such as polycyclic aromatic hydrocarbons (PAHs) are formed during the grilling or smoking of meat. When fat from the meat drips on an open flame, the rising smoke leaves deposits of PAHs on the meat. There is strong experimental evidence that HCAs and PAHs contribute to certain cancers, including prostate cancer, Stern says.
“The observations from this study alone are not enough to make any health recommendations, but given the few modifiable risk factors known for prostate cancer, the understanding of dietary factors and cooking methods are of high public health relevance.”