With barbeque season in full-swing, it’s the perfect time to learn how to protect yourself from carcinogen exposure produced by cooking meat. Heterocyclic amines (HCAs) are chemicals that are formed on the surface of meat when it is cooked at high temperatures. HCAs are classified as carcinogens because they can damage DNA, which increases cancer risk. Polycyclic aromatic hydrocarbons (PAHs) are another class of chemicals that can be carcinogenic. When meat juices drip onto the coals or heating elements and produce flames, PAHs are formed, and they then stick to the surface of the meat increasing carcinogen exposure. Both PAHs and HCAs have been shown to increase the development of several types of cancer in rodents. In humans, consuming large amounts of barbequed, fried, or well-done meat has been associated with higher risks of pancreatic, prostate, colorectal, and breast cancers.
Several factors can influence the level of HCA and PAH production during cooking. In this post I focus specifically on HCAs and outline some simple steps you can take to decrease their formation when cooking your favourite meat. For more details you can read a fantastic article written by the naturopathic doctor Jacob Schor (reference below).
Temperature is the number one factor that influences carcinogen exposure, with higher cooking temperatures generating more HCAs. This is important to know because cooking temperatures are greatly influenced by the cooking method. High-heat cooking methods such as barbequing, broiling, and frying tend to produce the most HCAs. To reduce HCA production, flip meat frequently to prevent the surface from reaching high temperatures. You can also consider using a low temperature cooking method such as slow-cooking.
Well-done meat contains more HCAs than rare meat that has been cooked using the same method. This may be the reason why consuming more well-done meat is associated with an increased risk of stomach adenocarcinoma. So, try to keep your meat in the rare to medium range. For chicken and ground meat such as hamburger, where there is an increased risk of food-borne pathogens, use a cooking thermometer to attain the recommended internal temperatures and prevent over-cooking.
Adding other foods to reduce HCA production
When certain foods are mixed into meat, like burgers or sausages, or when applied to meat as a marinade or rub, they can decrease the formation of HCAs. Fruit, specifically cherries, dried plums, and apples, can be mixed into burgers and sausages to reduce HCA production. A marinade with garlic (2 parts), onion (2 parts), and lemon juice (1 part), can act similarly and prevent HCA formation. Olive oil and rosemary may also decrease HCA production and can easily be used in many homemade marinades or rubs. In addition, one study showed that alcohol-based marinades including red wine, and especially beer marinades, can reduce HCA formation when pan-frying meat.
Decreasing the cancer-causing potential of HCAs may be possible by consuming certain foods that neutralize these chemicals and prevent them from causing harm. Testing done outside of the human body has shown that green, black, and rooibos teas, as well as blueberries, blackberries, kiwi, watermelon, spinach, and parsley can prevent HCAs from damaging DNA. Many cruciferous vegetables (e.g. broccoli, cabbage, kale, cauliflower) contain a compound called sulforphane that can also reduce the harmful effects of HCAs. So try adding some of these foods to meals that include meats cooked at high temperatures.
PAHs and HCAs can damage DNA and may increase your risk of developing several types of cancer. The safest way to enjoy meat is by removing excess skin and fat prior to cooking, using a low temperature, and turning the meat frequently. Using a marinade or rub made from olive oil (or beer!), garlic, onions, lemon, and rosemary prior to cooking can also reduce the formation of HCAs. Eating cruciferous vegetables, spinach, parsley, berries, or drinking green or black tea alongside your meat may help to neutralize the HCAs that you consume. In addition, decreasing your overall meat consumption can lessen your HCA and PAH exposure. On occasion, replace your hamburger with a barbequed portobello mushroom or a homemade baked black bean burger. Enjoy the rest of the barbeque season and cook safe friends!
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National Cancer Institute. Chemicals in meat cooked at high temperatures and cancer risk. 2015. Retrieved from http://www.cancer.gov/about-cancer/causes-prevention/risk/diet/cooked-meats-fact-sheet
Schor, J. Marinades reduce heterocyclic amines from primitive food preparation techniques. Natural Medicine Journal. 2010; 2(7).
Zheng, W, Lee, SA. Well-done meat intake, heterocyclic amine exposure, and cancer risk. Nutrition and Cancer. 2009; 61(4):437-446
Sarah Soles, BSc., ND