As cooking methods go, we generally recommend grilling or barbequing as a healthier way to cook, since it allows unhealthy fat to drip away. However, there may be another issue with the heat we’re using to cook and the very fat that’s dripping away.
It’s all in the chemistry. When we heat food up, chemical changes begin to happen – some good – like muscle fibres soften giving that tenderness to grilled meat. As well, heat helps to destroy bacteria, which makes food safer to eat.
Here’s the issue: when the fat from animal foods, like meat, pork, and lamb, hits hot coals, it undergoes a chemical transformation, creating compounds called polycyclic aromatic hydrocarbons (PAH). When meat is heated to high temperatures for cooking, we see the formation of compounds called heterocyclic amines (HCA).
What are these compounds and how are they important?
HCAs and PAHs are normal compounds created through chemical changes during the cooking of meat. They have been studied for some time and have notably shown up in reports from cancer institutions from around the world. These compounds are recognized by various health organizations, like the World Health Organization, as human carcinogens. In animal studies, these compounds were shown to be mutagenic, that is, they changed the DNA in animals increasing their cancer risk (National Cancer Institute, 2015). These statements, however, are the stuff news headlines are made of.
It sounds pretty dire, doesn’t it? Why on earth would any of us want to eat or breathe something that contains potential carcinogens? Let’s put this into perspective. We are, daily, surrounded by a number of noted carcinogens – car exhaust fumes, cigarette smoke, alcoholic beverages, ultraviolet light from the sun. I found this quote and I think it sums it up perfectly, “carcinogens do not cause cancer in every case, all the time”.
An American study done in North Carolina in 2003 looked at colon cancer risk and compared that with meat doneness, estimated HCA intake and cooking method. They found the association between cancer-causing compounds and cancer risk appeared higher in pan-fried meats and meats that are very well done in cooking (i.e. no pink spots). So, the longer we cook meat, the more these compounds will be produced. Current evidence indicates the highest compound forming meats are red meats that are charred, cooked for very long periods resulting in well done pieces of meat compared with grilled chicken and fish, which contain much lower amounts.
A great review by McAfee (2010) summarized the evidence looking at cancer risk and consumption of HCAs and PAHs with meat consumption and they surmised that we can only “speculate on the role of HCAs in carcinogenesis, as exact quantities within cooked red meat are likely to be very small”. In fact, there is no definitive link of cause and effect between these compounds and cancer in human studies. As with any disease, however, there will always be a number of risks and interactions involved, not simply one cause. Just as we know that red wine on its own doesn’t prevent heart disease, we must recognize that other dietary factors and environmental carcinogens will play a role, including some potential protective ones, like eating enough fruit and vegetables.
Knowing what we know, how can we reduce these compounds in our diets?
In many studies looking at HCAs and PHAs, scientists found that the formation of these compounds were reduced when marinades were used, when meat was thawed using a microwave and when meat was flipped frequently during cooking (Butler, 2003). Beyond this, we can trim off overly charred or blackened sections of meat before eating and to look for ways to lessen cooking time to prevent overcooking, and include meat alternatives (soy, lentils, beans) as great protein sources.
The World Cancer Research Fund’s cancer prevention report from 2007 recommends eating more plant-based foods vs. animal-based ones as a way to prevent cancer risk. This is a recommendation that extends beyond cancer risk reduction, as we recognize the many benefits of plant-based foods. This doesn’t necessarily mean, however, giving up meat altogether (unless you choose to). We know with many diseases where diet is a contributing factor that eliminating one food isn’t a guarantee for prevention. In fact, we know that many foods, including meats, can be healthy and nutritious, in moderation. So, if you’re going to fire up the grill this summer, keep these ideas in mind – modest meat intake, trying out some veggies options and watch the blackened bits.
Butler, L. (2003). Heterocyclic Amines, Meat Intake, and Association with Colon Cancer in a Population-based Study. Am. J. Epidemiol. 157 (5): 434-445. doi: 10.1093/aje/kwf221
McAfee, A.J. et al. (2010). Red meat consumption: An overview of the risks and benefits. Meat Science. 84,1–13. doi:10.1016/j.meatsci.2009.08.029
National Cancer Institute. (2015). Chemicals in Meat Cooked at High Temperatures and Cancer Risk. http://www.cancer.gov/about-cancer/causes-prevention/risk/diet/cooked-meats-fact-sheet
Schwarcz, J. (2005). Can red meat take the heat? Arts & Opinion. http://www.artsandopinion.com/2005_v4_n6/schwarcz-4.htm
Stewart BW, Wild CP (Eds.). (2014). World Cancer Report. World Health Organization: International Agency for Research on Cancer. http://publications.iarc.fr/Non-Series-Publications/World-Cancer-Reports/World-Cancer-Report-2014
World Cancer Research Fund / American Institute for Cancer Research. (2007). Food, Nutrition, Physical Activity, and the Prevention of Cancer: a Global Perspective. Washington, DC: AICR.
Photo source: Pixabay.com, Foodphoto.ca