JOE SCHWARCZ: CAN RED MEAT TAKE THE HEAT@Arts & Opinion

CAN RED MEAT TAKE THE HEAT?

by
Dr. JOE SCHWARCZ

Dr. Joe Schwarcz Dr. Joe Schwarcz is Director of McGill University’s Office for Science and Society. He hosts The Dr. Joe Show on Montreal's CJAD and has appeared hundreds of times on The Discovery Channel, CTV, CBC, TV Ontario and Global Television. Dr. Schwarcz also writes a newspaper column entitled The Right Chemistry and has authored four best sellers, Radar, Hula Hoops and Playful Pigs, The Genie in the Bottle, That's the Way the Cookie Crumbles, and Dr. Joe and What You Didn’t Know.

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The wienerschnitzel was so large it hung off the plate. Topped with a sprinkling of chopped parsley and lemon juice, it was an absolute treat. To this day, my mouth waters whenever I recall my first schnitzel experience. My aunt, who had arranged for us to come to Montreal after we had fled Hungary during the 1956 uprising, owned the “Riviera,” a European style restaurant. It was there that I was introduced to the delights of a serving of veal, pounded almost paper thin, battered in flour, eggs and breadcrumbs, and quickly fried to a golden brown. I just loved it. In fact, I still do. The Riviera is long gone, but I have learned to make a pretty acceptable schnitzel myself. But there is a difference. Science has entered the picture and my enjoyment is now tainted by nutritional concerns. Much as I hate to admit it, some pretty dark clouds hang over the frequent consumption of red meat, and fried foods in particular.

The words “red meat” and “cancer” now appear in the same sentence in the scientific literature with alarming frequency and articles about the role of diet in cancer commonly conclude that many cases can be prevented by dietary modification. The suggested changes usually involve increasing fruit and vegetable consumption while curbing the intake of red meat and foods cooked at a high temperature. Take for example a huge European study which enrolled almost half a million healthy men and women in the 1990s and followed their health status. After about five years, some 1300 cases of colorectal cancer had been detected and the lifestyles of these patients were then compared with those free of the disease. The major finding was that bowel cancer was associated with an intake of red meats and processed meats. Quantitatively, people who ate more than 160 grams of red or processed meat a day were 35% more likely to develop bowel cancer than those who ate less than 20 grams a day. And 160 grams is not a lot, eat a “quarter pounder” and you’ve got it. Chicken was not implicated and eating fish was actually associated with a lower risk of bowel cancer.

Exactly what the problem is with red and processed meats is hard to say, but it’s a good bet that heterocyclic amines (HCAs) are involved. Heating food unleashes a host of chemical changes, some of which, such as destroying bacteria, softening muscle fibers and developing flavor are desirable, while others are not. High temperatures allow compounds such as creatinine in meat to combine with aldehydes (glucose for example) to form heterocyclic amines, which are recognized carcinogens. The higher the temperature, the longer the cooking time, the more HCAs form. And these compounds have been implicated in more than bowel cancer. Red meat consumption is associated with prostate, stomach and pancreatic cancer, and researchers have also found that women who routinely eat very well done meat face a five-fold increase in breast cancer risk when compared with women who eat their meat rare or medium. Why chicken and fish are less risky isn’t clear but it may have to do with shorter cooking times. In any case, this is a welcome observation because chicken and particularly fish, are also deemed to be more heart healthy than red meat. At least as long as they are not fried! Harvard Medical School researchers who examined the heart function of some 5000 seniors found that those who ate broiled or baked fish frequently had lower heart rates, lower blood pressure and better blood flow to the heart while those who regularly ate fried fish or fast-food fish sandwiches actually showed a greater incidence of hardening of the coronary arteries and other heart problems. The likely culprit here is the fat used for frying.

I don’t know what the cooks in the Riviera used to fry my wienerschnitzel back in the 1950s, but it was probably some sort of animal fat. As scientists learned more about the cholesterol raising properties of such saturated fats, they pushed to replace them with the polyunsaturated fats found in vegetable oils. These, though, degraded more easily when heated and could not be reused as often as the saturated fats. A remedy was found in the form of “partially hydrogenated” vegetable oils which had better keeping qualities, but alas, a new problem cropped up. Hydrogenation converted some of the unsaturated fats into the now notorious “trans fats,” which were as bad for the heart as the animal fats. Today, trans fats have become a pariah and movements are afoot to drive them out of our food supply. But what do we replace them with? Going back to beef tallow or lard is hardly the answer. Frying in unsaturated vegetable oils eliminates the trans fat problem but let’s not get too comfortable with these either. There is the emerging issue of trans-4-hydroxy-2-nonenal, or “HNE.”

Chances are you haven’t heard of HNE, but it is causing somewhat of a ruckus in the scientific community. HNE forms when polyunsaturated fats, that is those containing several carbon-carbon double bonds, react with oxygen. Such fats are present in cell membranes and can give rise to HNE which then can travel through the bloodstream. The bad news is that HNE has been linked with cardiovascular disease, Parkinson’s, Alzheimer’s, liver and kidney ailments, and even cancer. And here is what we really don’t want to hear: HNE forms when polyunsaturated oils, particularly those containing linoleic acid (corn, soy, canola), are heated, especially if heated repeatedly. Those golden fries in restaurants may be laden with HNE! Now for the good news. Monounsaturated fats like peanut oil or olive oil are far less prone to such contamination. Alas, these are not commonly used in restaurants so limiting fried foods when eating out is really important. But I still won’t give up on making my wienerschnitzel at home. I do it less often and fry it in olive oil. Why? Because there is more to life than worrying about every morsel of food we put into our mouth.