health@mit

SUMMER 2006

Where there's smoke…

Secrets of safer grilling

Almost nothing signals the start of summer like the aroma of backyard grills being fired up and put to work. "I cook out a couple times a week during the good weather," says MIT Medical facilities manager Bob Bright. "I grill a lot of lean meat, like chicken," he reports. "I also love hot dogs and sausage, but I know they're not good for me, so I don't eat them very often."

In recent years, Bright has made increasing efforts to stay healthy by exercising regularly, adding more fruits and vegetables to his diet, and avoiding saturated fats. So, when he heard that grilled meat could be a source of carcinogens, he wasn't sure how to respond. "I always thought grilling was a healthier way to cook," he laments. "And everything tastes better on the grill!"

HCAs, PAHs, HUH?

According to MIT Medical's chief of medicine, David Diamond, M.D., a specialist in environmental medicine, while the cancer risk may be relatively low, two types of potential carcinogens may be found in grilled meats. The first consists of polycyclic aromatic hydrocarbons (PAHs). These are found in the smoke that billows up when fat drips from meat or fish onto a heat source. When this smoke envelopes the meat on the grilling rack, it efficiently transfers PAHs to the meat's surface.

The second type of carcinogen, heterocyclic amines (HCAs), has more to do with temperature than cooking method. HCAs are formed when high cooking temperatures cause a chemical reaction between naturally occurring amino acids and sugars in the meat and creatine, which is found in muscle tissue. HCAs have been found not only in grilled meats, but also in fried and broiled meats, especially well-done red meat.

Making grilling safer: marinate and pre-cook

Fortunately, says Diamond, backyard chefs can reduce or avoid most grilling-related carcinogens. PAHs can be reduced by avoiding fatty meats that tend to drip onto the heat source and by cooking with indirect heat rather than placing foods directly over coals. "And they can be avoided completely if you stop fat from dripping on the heat source by using a layer of aluminum foil between meat and coals," Diamond says.

To prevent HCAs, Diamond suggests following these suggestions from the American Cancer Society, the American Institute for Cancer Research, and the National Cancer Institute:

• Precook meat in the microwave. Before grilling or broiling, pre-cook meat or poultry in the microwave and throw away the juice, which contains most of the potentially harmful chemicals. (To prevent meat from spoiling, grill it immediately after precooking.)
• Marinate meat and poultry. The research is clear: marinating meats, in any kind of marinade, even for just a few minutes before grilling or broiling, can reduce HCAs by 90 percent or more. Researchers don't know why marinating has such a dramatic effect. It may be because the marinade sets up a barrier against heat, or perhaps marinating draws out chemical precursors of carcinogens from the meat. (Again, to keep bacteria from growing, keep food in the refrigerator while marinating, and never add uncooked marinade to cooked meat or poultry.)
• Don't grill frozen meat. When frozen meat is grilled, its surface is overexposed to high temperatures while the inside is warmed very slowly. Always thaw frozen meat or poultry in the refrigerator before cooking.
• Grill meat in small chunks. Small pieces of meat cook faster, giving HCAs less time to form.
• Lower the heat. There are several ways to grill foods at lower temperatures. One is to use a gas grill, which cooks at a lower temperature than charcoal or wood fires and makes it easier to control the temperature. Charcoal aficionados should aim to increase the distance between the food and the hot coals. Do this by spreading coals thinly, by raising the grill rack, or by raking all the coals to one side and cooking the food on the opposite side. And always use hardwood charcoal, which burns at lower temperatures than mesquite or other soft woods.
• Well-done grilling means no well-done meat. Some people actually like charred chicken, steaks, and hamburgers. But well-done meat, regardless of cooking method, contains the most HCAs and should be avoided. (Of course, going to the other extreme is unhealthy, too. It's important to cook meat well enough to eliminate illness-causing bacteria, like E. coli.)

Finally, says MIT Medical nutritionist Anna Jasonides, R.D., grilling isn't just about meats. "Grilled fruits and vegetables are delicious and nutritious," she notes. "You can grill everything from zucchini and peppers to pineapple and peaches!"

For his part, Bright says these easy, common-sense suggestions for safer grilling come as good news. "Giving up fatty snack foods for my health was one thing," he says. "But I wasn't about to hang up my barbeque tongs without a fight!"