TEN TOP FOOD MYTHS

Much of what we thought we knew about a healthy diet is simply rubbish.

Nuggets of nutritional knowledge or junk-food science? It turns out that many popular beliefs about what we put on our plates contain not even a kernel of truth. Here, we bust 10 of the top food myths.

1· Going gluten free can magically melt off excess weight.

As someone who treats obesity, Dr. Yoni Freedhoff, medical director of Ottawa's Bariatric Medical Institute and an assistant professor of family medicine at the University of Ottawa, says the food myth he encounters most often is that "bread is evil and that eating it will somehow, independently of its calories, cause weight gain."

Nurtured by the low-carb-diet craze, this fallacy has been further fortified by the growing awareness of celiac disease and gluten intolerance, and by books that blame our nation's expanding waistlines on wheat consumption. (Celiac disease is a condition in which eating gluten-proteins found in wheat, barley, and rye-result s in damage to the intestinal lining, preventing proper absorption of nutrients, which in turn leads to problems ranging from bloating to nutritional deficiencies. Gluten intolerance is a sensitivity that causes digestive symptoms but no damage.)

True, some people who don't have celiac disease shed weight after adopting a gluten-free diet, but that doesn't prove wheat or gluten was responsible for packing on those pounds in the first place, according to Rosie Schwartz, a Toronto registered dietitian and author of The Enlightened Eater's Whole Foods Guide: Harvest the Power ofPhyto Foods (Viking Canada, 2003). Giving up gluten means cutting out many highly processed, calorie-crammed, nutritionally empty foods, which-assuming you don't simply swap them for celiac-friendly versions-itself aids in weight control. Similarly, passing up the breadbasket at a restaurant reduces your calorie intake, which, as we all know, is a key to weight management. But, because diets high in whole grains such as wheat, barley, and rye have been linked with a decreased risk for multiple health woes including Type 2 diabetes, Schwartz recommends that, rather than ditching gluten, you choose nutrient-dense, fibre-rich carbohydrates such as whole-grain pasta or bread, pairing them with protein at meals and snacks. Not only will you avoid needlessly missing out on the health benefits of whole grains, but the combination of fibre and protein will make you feel full faster, and longer, than will eating plain white carbs, thereby reducing the odds that you'll overindulge.

2. "Natural" deli meats are healthier than regular cold cuts.

Most deli meats (and other processed meats, such as bacon and hot dogs) contain preservatives called nitrites, which have been tentatively linked to colon cancer, and the so-called natural versions are no exception; the only difference is that in the latter, those chemicals are derived from cultured celery extract rather than synthesized in the lab. In fact, an analysis performed for CBC's Marketplace reportedly found that the nitrites in "natural" deli meats were chemically identical to their "unnatural" counterparts.

Nitrites aside, there's no evidence natural deli meats are nutritionally superior in other ways, notes Gloria Tsang, a Vancouver registered dietitian and founding editor of the online nutrition portal Health Castle. com. "I don't see them containing less sodium or fat," she notes. And while studies have linked consumption of processed meats to an increased risk of developing colon cancer and Type 2 diabetes, it's not clear whether the culprit is a single compound, such as salt, fat, or nitrites, or some combination thereof (Salt has been implicated in gastric cancer, for example.) What's more, after reviewing the available evidence, an expert panel of the World Cancer Research Fund and the American Institute for Cancer Research was unable to pinpoint a safe level of deli consumption with respect to colon cancer risk.

3. If my cholesterol levels are good, it's safe to eat lots of red meat.

Prepared properly, in modest amounts, red meat can be a part of a healthy diet; among other things, it's rich in readily absorbed iron. However, there's good evidence that eating more than 500 grams (roughly a pound) per week is associated with an increased risk for colon cancer, a risk level that appears to continue climbing in tandem with the level of consumption.

"Red meat by itself puts more iron and saturated fat into the digestive system, and a lot of the iron goes undigested and ends up in the colon," explains James Kirkland, an associate professor of human health and nutritional sciences at the University of Guelph. Iron is a prooxidant, meaning it produces by-products that can damage cells, which, over time, could trigger tumour formation.

Kirkland adds that the relationship between colon cancer and red meat consumption increases with cooking time and temperature: the more well done the meat, and the hotter the stove or grill, the greater the risk. "The chemistry behind that is very well recognized;' he says. "When you start cooking the meat more extensively, carcinogens form."

4. All types of peanut butter reduce diabetes risk.

There's good research linking peanut and peanut-butter consumption with a variety of health benefits, including a decrease in Type 2 diabetes risk, but you may be missing out, depending on the brand you buy.

"In the United States, if a product contains less than 90 per cent peanuts, it must be called a peanut-butter spread, but Health Canada and the Canadian Food Inspection Agency do not have any such regulation," Schwartz explains. Consequently, the contents of the jar in your cupboard could be something more akin to peanut-flavoured icing, since some brands contain ingredients such as icing sugar, unhealt hy fats, and corn-syrup solids. (Incidentally, since peanuts contain healthy fats, reducedor low-fat versions aren't desirable: the fat content is cut by substituting nonnutritious fillers.) "You're not going to get the same healt h benefits if the product contains 75 per cent peanuts as you would if it's 95 per cent or 100 per cent peanuts," Schwartz stresses.

So how can you choose a peanut butter brand that's most likely to deliver on the health promises held out by research? Check the list of ingredients on the label: the best options will contain only peanuts. Another tip: «Look at the amount of protein listed on the label," suggests Massimo Marcone, an associate professor in the Department of Food Science at the University of Guelph. (The higher the level of protein, the more peanuts the product contains, and the less carbohydrate and other fillers."

5. "Whole wheat" equals "whole grain."

«When you see (whole wheat' or (100% whole wheat' on the label, you assume you're getting a whole grain," Schwartz says, "but maybe not"

While writing a column for the National Post, Schwartz discovered that, according to Canadian regulations, flour can have much of the germ (the most nutritious part of the grain) removed and still be labelled «whole wheat." (In fact, the productthat prompted Schwartz to probe the rules around flour labelling was a brand of white flour with added bran that carried the claim «contains the goodness of whole wheat.") What's more, even many nutrition professionals were unaware of the loophole. «I contacted people at Ryerson who teach nutrition- they didn't know:' Schwartz says. "I did a survey of dietitians across the country-and they didn't know."

So how can you tell if your so-called whole wheat flour hasn't had most of the germ stripped away? "You have to look for the words 'whole grain whole wheat'" on the ingredients list, Schwartz says.

6. The omega-3 fats in fish are interchangeable with those found in flax and walnuts.

The main omega-3 fat found in plants, alpha-linolenic acid (ALA), is what's known as a short-chain omega-3, while those in fish, docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), are referred to as long-chain omega-3s.

"The active omega-3s in the body- the ones that need to get to certain sites like the brain and the retina, and accumulate there to exhibit the beneficial effects- are DHA and EPA," explains Dr. Bruce Holub, an omega-3 researcher and professor emeritus in the Department of Human Health and Nutritional Sciences at the University of Guelph. It's these longchain omega-3s that have been shown to improve heart health, reduce inflammation, and possibly lower the risk for certain eye diseases.

Since the body can't manufacture ALA from scratch, it's the only omega-3 dubbed an "essential" fatty acid. But while our bodies can convert ALA into DHA and EPA, the process, which takes place primarily in the liver, isn't very efficient. "In all of the human studies done to date that have assessed the capacity for conversion, the average conversion efficiency from ALA all the way to DHA has been estimated to be about four per cent," Holub notes, with women scoring somewhat better than men.

That means the easiest way to get the amount of DHA and EPA your body needs is to eat fatty fish or take a fish-oil supplement. Dietitians of Canada and the American Dietetic Association suggest getting 500 mg of DHA plus EPA per day for general health, and the American Heart Association recommends double that amount for people who have coronary heart disease. To put that in perspective, 85 grams (3 oz) of wild Atlantic salmon contain more than 1,400 mg of DHA and EPA. However, in Canada, "our average intake is only about 125 mg of DHA plus EPA per day," Holub says, compared with 1,000 mg for residents of Japan.

Want to get some of your long-chain omega-3s from other foods? Check labels for levels of DHA, dietitian Tsang advises, since many products advertising added omega-3s contain only ALA. An omega-3 egg, for instance, contains about 80 mg of DHA, along with roughly 300 mg of ALA. (Omega-3 eggs are obtained by feeding hens flaxseed: chickens are capable of turning about 20 per cent of the ALA they consume into DHA.)

7. Everyone can reap health benefits from taking a multivitamin.

There's no evidence multivitamins are beneficial to healthy people 55 or older, Kirkland says. What's more, some have the potential to cause harm: taking a formulation with too much extra iron may cause liver damage, Marcone notes, while an overabundance of folic acid from supplements and fortified foods (such as flour) can mask the symptoms of B12 deficiency (a common condition that, if unchecked, can lead to problems such as permanent nerve damage) and encourage the development of certain cancers. (On the other hand, it's virtually impossible to overdo folic acid by eating foods containing folate, which our bodies turn into folic acid.)

Consequently, "rather than taking supplements on your own, it's a good idea to have a regular physical and blood work," Kirkland says. A knowledgeable health professional can evaluate your nutritional status and, if necessary, recommend an appropriate supplement. If you decide to self-prescribe nonetheless, make sure you choose a multivitamin formulated for someone of your age and sex; for example, those intended for people 55 or older typically contain little or no iron. (Note: Health Canada does recommend that everyone over 50 take 400 IU of supplemental vitamin D per day, because, at that age, our skin becomes less efficient at manufacturing the nutrient in response to sunlight exposure. Since 10 to 30 per cent of people over 50 have difficulty absorbing sufficient B12 from food, the agency also suggests people in this age group eat foods fortified with B12 or consider taking a supplement.)

8. It's hard to get sufficient protein from a vegetarian or vegan diet.

(Vegans eat no animal products, including dairy and eggs.) "It's not hard at all," stresses Doug McNish, a raw/vegan chef in Toronto and author of Eat Raw, Eat Well: 400 Raw, Vegan and Gluten-Free Recipes (Robert Rose, 2012). (Raw chef? Isn't that a contradiction? Nope. A wide variety of plant foods contain protein, including beans, legumes, nuts and nut butters, and seeds. "Hemp seed is probably my favourite source," McNish says. "One tablespoon contains up to 5 grams of protein, which is equivalent to an egg. If you sprinkle three tablespoons of hemp seed on a salad, that's 15 grams." (Many bulk-food and health food stores stock hemp seed.)

That alone makes a sizable dent in the minimum 0.8 gram of protein per kilogram of body weight that's recommended for a relatively sedentary person, or even the 1.2 to 1.7 grams/kilo suggested for more athletic, active people. (How do those numbers add up? "If someone weighs 60 kilograms, that's roughly 60 grams of protein," says Lindzie O'Reilly, lead dietitian with the Health and Performance Centre at the University of Guelph. "If you spread that over the course of a day, that might mean aiming for 15 grams at each meal and five to 10 grams for snacks." )

Incidentally, vegetarian food has come a long way since the days of bland brown rice and limp sprouts: you can now easily find recipes for delicious vegan versions of every thing from brownies to gravy and soup stock. Of course, that brings us to correct another myth; that a food is free of animal products doesn't necessarily mean it's inherently healthy. For instance, french fries made in vegetable oil are vegan.

9. All soy-based foods are nutritious and/or heart-healthy

Some soy-based products, such as certain veggie dogs and cold cuts, are highly processed, making them foods that should be consumed sparingly. For instance, "Many soy protein bars and frozen soy patties are made with soy protein isolate," Tsang explains, meaning that they contain only a fraction of the nutrients found in whole soybeans, and in a highly refined form. "I've even seen light soy milks made with water and soy flour,"she adds. Such products are unlikely to confer benefits comparable to those of less processed soy foods, which have been shown to curb high blood pressure, reduce unhealthy LDL cholesterol and triglycerides, buoy levels of beneficial HDL cholesterol, and improve blood-vessel elasticity. Consequently, Tsang suggests that, when choosing soy foods, you scan the ingredients list for the words "whole soy" or "whole soybeans."

10. Artificial sweeteners lead to weight gain.

While some studies have found that diet-soda drinkers, for example, tend to gain more weight or grow larger around the waist than do people who avoid the stuff, the Un iversit y of Ottawa's Dr. Freedhoff emphasizes that such research doesn't support the theory that artificial sweeteners or other ingredients in diet soda are the underlying cause. The purported link could be due to other factors, such as the possibility that people who drink diet soda overestimate the number of calories they've "saved" and splurge excessively elsewhere ("I skipped the sugary soda, so I' ll get bacon and cheese on my burger and upsize my fries.")

In fact, the purported connection between weight gain and sugar substitutes dissolves in higher-quality research. "In virtually every study I've come across looking at artificial sweeteners for weight loss or weight management "artificial sweeteners have been shown to be beneficial," Freedhoff says. "They have not been linked to weight gain.

By Wendy Haaf in "Good Times" vol. 23, n.8, September 2012, Canada, excerpts pp. 20-26. Adapted and illustrated to be post by Leopoldo Costa.