As the warm weather arrives, so does barbecue season - the time of year we like to enjoy the taste of grilled foods, especially meat. But depending on what you throw on the grill - and for how long - you may be jeopardizing your health.
A new study published in the May issue of the American Journal of Clinical Nutrition suggests that eating plenty of grilled - and well browned - meat can boost the risk of colorectal cancer, especially if your diet lacks fruit and vegetables.
A number of studies have demonstrated that high intakes of red meat and processed meat increase the risk of colorectal cancer.
Experts recommend consuming less than 18 ounces (500 grams) of red meat (beef, pork, lamb, goat) a week and to limit or avoid processed meats such as bacon, sausage, hot dogs and deli meat.
It's thought that compounds in cooked meat called heterocyclic amines (HCAs) are to blame. Grilling, broiling and frying meat at high temperatures creates HCAs that are not present in uncooked meat. They're formed when amino acids (the building blocks of protein) and creatine (a natural compound found in muscle meats) react at high temperatures.
Researchers have identified at least 20 HCAs formed during cooking meat that may increase cancer risk. One in particular, called PhIP, is the most abundant HCA in our diet. While HCAs have been shown to promote cancer in animals, only a few studies have explored the link in humans.
In the current study, researchers from Europe investigated the link between HCA intake and the development of colorectal adenomas in 25,540 men and women aged 35 to 65 years. (Adenomas are benign polyps that can develop into cancer.) The researchers asked participants about types of meat consumed, cooking methods and degree of browning - factors that influence the formation of HCAs. Daily intakes of HCAs, including PhIP, were also calculated.
Compared with those with the lowest intake of PhIP, individuals who consumed the most had a 46 per cent greater risk of developing adenomas. This result was supported by the finding that people who reported the highest - compared with the lowest - intake of "strongly" or "extremely" browned meat had an increased risk of developing adenomas.
But it seems that what else you eat - or don't eat - may alter the harmful effects of HCAs in the colon. Studies in the lab have suggested that flavonoids, natural compounds found in fruit, vegetables, tea and red wine, can block the formation of HCAs. Yet, it's not known if consuming flavonoid-rich foods can protect humans from HCAs.
In this study, in people who had the lowest intake of flavonoids, the risk of developing precancerous polyps increased progressively the more HCAs they consumed. Among those who consumed the most flavonoids, there was no significant association between HCAs and colorectal adenomas.
Interestingly, a second study published in this same journal reported that among people who ate the most red and processed meat, the increased risk of colon cancer diminished with increasing fruit and vegetable intake.
There's also concern that fat dripping from meat onto hot coals, stones or burners creates additional carcinogens called polycyclic aromatic hydrocarbons. Once these chemicals are formed, they're deposited back onto food by smoke and flare-ups.
I'm not suggesting that you ban grilled meat from your diet. You need to consider how often you grill, the types of foods you grill, how well done you cook meat and what other foods you add to your plate.
Practise the following tips to help minimize the formation of harmful chemicals when you barbecue.
KEEP PORTIONS SMALL
For safer grilled meats, keep portions small to cut down on grilling time. Instead of grilling a whole steak, make kebabs - they cook more quickly.
For meats that require longer cooking times (such as larger cuts), partly cook in the microwave, drain the juices and then finish on the barbecue. Research has shown that microwaving meat for two minutes prior to grilling can result in a 90-per-cent reduction in HCA content.
Marinating meat for 10 minutes before grilling can reduce the formation of HCAs substantially. A marinade may act as a barrier, keeping flames from touching the meat. Certain ingredients in a marinade - vinegar, citrus juice, vegetable oil or spices - may also prevent carcinogen formation.
LOWER THE TEMPERATURE
Cooking at a lower temperature will decrease the formation of HCAs. Turn the gas down or wait for the charcoal to become low-burning embers. (Oven roasting and baking are done at lower temperatures so fewer HCAs are likely to form.)
To prevent fat drippings, choose lean meats such as sirloin, tenderloin, inside round and flank steak and trim visible fat before grilling. Avoid letting juices drip into the flames or coals. Remove all charred and burnt portions before eating.
FLIP BURGERS OFTEN
A study published in the Journal of the National Cancer Institute found that burgers cooked at a lower temperature and turned every minute while cooking had 75 to 95 per cent fewer carcinogens than burgers turned only once after five minutes of cooking.
To kill harmful bacteria in ground meat, beef burgers must be cooked to an internal temperature of 71 C (160 F) and poultry burgers to 80 C (175 F). Use a digital meat thermometer to determine if your burgers are safe to eat. Don't judge by colour - beef patties may be brown in the centre before getting to a safe temperature, or may stay pink even after reaching the right one.
INCREASE FRUIT AND VEGETABLES
To increase your intake of disease-fighting flavonoids, include seven to 10 servings of fruit and vegetables in your daily diet. Good sources of flavonoids include berries, cherries, red grapes, apples, citrus fruit, broccoli, kale and onions.
(One serving is equivalent to one medium fruit, ¼ cup of dried fruit, ½ cup cooked or raw vegetables, and one cup of salad greens.)
ADD FRUIT TO YOUR BURGERS
Research from Michigan State University determined that adding one cup of mashed cherries to a pound of ground meat suppressed carcinogen formation by 90 per cent.
Leslie Beck, a Toronto-based dietitian at the Medcan Clinic, is on CTV's Canada AM every Wednesday. Her website is lesliebeck.com.