Heterocyclic Amines (HCA)

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1 If you follow a primarily paleo way of eating you would probably have stumbled across a few articles that suggest a link between certain diseases and eating meat that s been cooked a certain way: One study found that people who prefer their red meat well done are 8.8 times more likely to get colorectal cancer than people who prefer their red meat rare. Another study found that well done meat seems to increase the risk of pancreatic cancer. And a recent review of several different studies found that consumption of well-done meat is associated with elevated cancer risk in humans. Cooking isn t bad, of course. It makes food taste better, gives us access to a wider range of foods like starches that would otherwise be fairly indigestible, kills food-borne pathogens, improves the texture of foods (meat becomes more tender, fat renders, vegetables soften), and increases the calories we can extract from food. But there s a dark side to cooking. Depending on the methods and ingredients you use and the temperature you apply, cooking can create carcinogenic (cancer causing) and toxic compounds, and oxidized fats and these may be involved in some of the diseases studied. It may not be the meat itself, but how we treat the meat. So what compounds should we be worrying about? Heterocyclic Amines (HCA) When meat is directly exposed to high temperature, the amino acids, sugars, and creatine within it react to form heterocyclic amines (HCA). In animal studies, HCAs are mutagenic they provoke harmful DNA mutations, can change gene expression, and cause cancer. Epidemiological studies link HCA intake in humans to many of these same cancers (including cancer of the prostate, pancreas, and colon). Caution appears to be warranted. Advanced Glycation Endproducts When steak is browned, when sugar is caramelized, or when you get a nice crust going on that roast, you re creating advanced glycation endproducts via the Maillard reaction. Most AGEs actually form endogenously, inside our bodies, but dietary AGEs appear to have some negative 1 / 6

2 effects of their own. Dietary AGEs have been shown to drain a person s antioxidant stores, opening them up to an inflammatory cascade that includes insulin resistance and, potentially, diabetes, while low-age diets can increase insulin sensitivity in humans. Oxidized Lipids Polyunsaturated fatty acids in meat (or in the seed oils used to marinade the meat) can become oxidized when exposed to high heat. When eaten, these oxidized fats are incorporated into circulating lipids, thus increasing the risk of atherosclerosis. The easiest way to minimize your exposure to heat-related toxins is to emphasize gentle cooking methods and de-emphasize higher heat methods. More abrasive cooking methods include: The traditinal braai the worst, grilling is consistently associated with higher levels of HCA Pan-frying Deep frying Broiling Smoking Searing Blackening Incinerating Gentler cooking methods include: Steaming Poaching Boiling Braising 2 / 6

3 Simmering Baking Pressure cooking The above all limit the formation of HCAs, AGEs, and oxidized lipids. They ll take you most of the way, but there are other variables to tweak (or at least be aware of) for greater protection: Cooking temperature Most studies indicate that 150 ºC, results in minimal HCA formation, even when pan-frying; 200 ºC is when the carcinogens really start accumulating quickly. As for AGEs, watch for browning. That s the Maillard reaction, and it s a good basic indicator of AGE formation. Creatine content of the meat The more creatine in the meat, the more HCA will be formed. That s why grilled salmon has more HCA than grilled burger. Saturation of the fat The more saturated the fat you use to cook, the more resistant it is to oxidation from heat exposure. Highly saturated coconut oil is far better than polyunsaturated sunflower oil, for example. Same goes for the fat in the meat; ruminant fat is more resistant to oxidation than chicken fat. Antioxidant content of the fat Some fats come with antioxidants that increase their resistance to heat. Even though it contains ample amounts of polyunsaturated fat, sesame oil is quite resistant to heat because of the antioxidants it bears. Extra virgin olive oil is another example of a good fat high in antioxidants however it is more heat sensitive, losing a lot of health benefits if heated too high. Therefore olive oil is best eaten on salads. Antioxidant content of the meat Pasture reared animals allowed to eat fresh grass, wild forage and herbs will effectively produce antioxidant-infused meat with greater oxidative stability than animals raised on concentrated feed. Protective foods consumed with the meal Certain foods seem to mitigate or even negate the harmful effects of heat-related toxins. Interestingly, many of them appear to confirm the 3 / 6

4 healthfulness of certain cultural traditions: Cruciferous vegetables like broccoli, cauliflower, and bok choy are highly protective against HCA mutagenicity. Maybe that s why steamed broccoli goes so well with steak. Coffee contains polyphenols and fibers that can bind and inhibit HCAs. Maybe that s why an after-dinner espresso or coffee is a common tradition in many cuisines. Red wine polyphenols inhibit carcinogen action in the gut after meat consumption. Maybe that s why red wine tastes so good with red meat it s actually healthier that way. Chlorella when taken with or immediately before a meal containing HCA inhibits its mutagenicity. Pretty much any plant food you eat with your meat, especially the colourful ones, will have a favorable impact on carcinogen formation, lipid oxidation, or mutagenicity. Blueberries, beetroot, salad greens, carrots, tomatoes, apple slices, spices it s hard to go wrong (just make sure that any spice is non-irradiated otherwise you are negating the good effects). Marinades Almost uniformly, marinating your meat will reduce the formation of toxic compounds like HCA and AGE, even if you grill it or pan-fry it. Use a quality antioxidant rich fat, like coconut oil; an acidic medium, like citrus juice or apple cider vinegar; and some antioxidant rich flavorings, like herbs, peppers, garlic, ginger, and spices like turmeric or cayenne and you ll probably produce a marinade capable of inhibiting toxin formation. Maybe not completely, maybe a few AGEs or HCAs will slip through, but anything is better than just throwing it on the braai or in the pan naked and dry. For some ideas that will surely help make your meats healthier and more delicious. The ingredients of the marinade matter. Sugar, for example, will increase the formation of heterocyclic amines, especially when combined with soy sauce. In other words, it s not as simple as saying this ingredient increases the risk because other ingredients can counter or mitigate the effect. A good general rule when making marinades: the more herbs and spices you use, the more protective (and better-tasting) your marinade. Ground rules for cooking: 4 / 6

5 Use liquid whenever possible. Water, stock, coffee, wine, even a bit of citrus juice will help reduce the formation of harmful compounds. Generally, any cooking method is made more gentle with the addition of liquid. Keep the temperature low when applying direct heat. Stir-frying, pan-frying, grilling try to keep the temperature on medium-low to medium. Learn to love rare to medium-rare meat and avoid medium well to well-done meat. Most epidemiological studies linking cooked meat to cancer only find positive associations with well-done meat. Besides, well-done steak is a culinary travesty and you should already avoid it on principle. Even when pan-frying or grilling, it s usually only the well-done burgers that form lots of carcinogens. Marinate, marinate, marinate. Plan ahead so that you can soak your meat in some antioxidant rich medium or another. Even ten to fifteen minutes before cooking can be effective. If you don t have time to marinate your meat, apply spices and herbs to the surface before cooking. Add some chopped garlic and ginger (or even garlic powder and ginger powder) to your steaks, some minced thyme and rosemary to your lamb, and cumin and turmeric to your chicken or use them all at once! Even black pepper can help. When preparing ground meat, mix the spices and herbs directly into the meat, not just on the surface of your formed burgers. Drink wine, eat broccoli, have espresso, and eat other mitigatory foods alongside your meat. Luckily, people on a paleo eating plan aren t just downing charred steak and nothing else. They re eating plenty of plants, too. Regularly make complex curries, tagines, goulashes, and other stews, which incorporate all the protective elements in one tasty package: liquid, spices/herbs, low temperature, gentle cooking. When making any starchy root dish that involves applying high heat to obtain a crispy exterior, 5 / 6

6 start with pre-cooked tubers. So, if you re doing French fries, cook the potatoes the day before and keep them in the fridge (this will produce resistant starches). Peel them, slice them into the fry shape of your choice, and lightly sauté each side in a stable cooking fat like ghee or coconut oil over medium heat. Since you don t have to worry about cooking the interior and it only takes a couple minutes to get a nice crust on each side, your cooking time is reduced by about 80% and the temperature needed is far lower as well. Fewer carcinogens and less lipid oxidation. Ultimately, healthy eating is about striking a balance. You can sear your steaks and live long just don t do so exclusively or eschew healthy plant foods alongside them. You can throw some chicken on the barbie but to mitigate the risks, just make sure they re marinated! 6 / 6