Foods That Harm, Foods That Heal
North American eating habits have changed over the last few decades.
Butter and Margarine
North American eating habits have changed over the last few decades, and nowhere is this more obvious than in the supermarket dairy case. Where butter once reigned, we now have a puzzling array of margarines and other substitutes from which to choose.
More and more people use margarine instead of butter because they believe it is the more healthful of the two spreads. Many people think that butter has more calories than margarine, but butter and margarine have about the same calories and are a major source of fat calories in the North American diet. Although most people agree that butter is more flavourful than margarine, they also know it is relatively high in dietary cholesterol and that the fat in butter is mostly saturated. Saturated fats are presumed to raise blood cholesterol levels more than other types of fat and to increase the risk of obesity, cancers and other diseases.
Is margarine more healthful than butter? Doubts were raised in 1993, when Harvard researchers concluded that some types of margarine may actually increase the risk of heart disease more than butter. Understandably, this added fuel—and confusion—to the “butter versus margarine” debate. The controversy lies in the level of trans fatty acids. (See sidebar “What Are Trans Fatty Acids?”) In general, the more solid the margarine is at room temperature, the more trans fat it contains. These days, many margarine manufacturers are changing their formulations to make products that do not contain trans fats.
Choose soft-tub margarine made with nonhydrogenated fats. Check labels and select a product with high levels of monounsaturated and polyunsaturated fats; margarines made from canola, safflower, sunflower, olive, and corn oils are all good choices. Avoid products with hydrogenated or partially hydrogenated oils; they have more trans fatty acids than the other types do.
While it’s no secret that butter tastes better than margarine, it’s increasingly difficult to tell the difference. Whipped or light butter often loses some of its natural flavour; conversely, mixing a little butter with margarine gives it a more buttery taste. Butter-substitute powders or sprinkles are virtually fat-free, deriving their flavour from the essence of butter. These products won’t spread, but they melt when sprinkled on vegetables or other hot dishes. Salt is used to flavour both butter and margarine; anyone on a low-sodium diet should look for unsalted varieties.
Used sparingly, both butter and margarine can be incorporated into a healthful diet, and they are a good source of vitamins A and D. A little butter goes a long way; a teaspoon imparts as much flavour as a tablespoon, with one third the fat. Further reduce butter or margarine by combining it with herbs, spices or low-fat ingredients; for example, top baked potatoes with chives and blended nonfat cottage cheese. When making cakes, cut the amount of butter or margarine by one third to one half; top whole-grain breads with fruit preserves.
What Are Trans Fatty Acids?
Trans fatty acids are produced when a vegetable oil is hydrogenated. Hydrogenation is a process used by many manufacturers to make liquid oil more solid (as in the manufacturing of spreads). This process improves shelf life and the stability of many baked goods and processed foods. Unfortunately, the process of hydrogenation creates trans fatty acids. Studies suggest that trans fats raise LDL (bad) cholesterol and also lower our HDL (good) cholesterol, increasing risk of heart disease. Some experts say that eating too much trans fats may be as bad or even worse than eating too much saturated fat.
The primary sources of trans fats in the North American diet are partially hydrogenated vegetable oils used in the production of shortenings and hydrogenated margarine. These are used extensively in food preparation. The foods most likely to contain trans fats are processed foods like chips, breakfast waffles, doughnuts, pastries, cookies, crackers, fast food products like deep-fried sandwiches and french fries. They are also in some margarines and spreads.
Having a trans-fat-free diet is pretty difficult and probably not necessary, but reducing your intake of trans fats is very important. Read labels and look for the listing of trans fats on packaged foods. You can also find trans fats in foods by looking for the words “hydrogenated vegetable oils” or “partially hydrogenated vegetable oils” in the ingredient list.
The best advice regarding these fats is to limit your intake of deep-fried, processed fatty foods, and snack foods. Look for processed foods and margarines made with nonhydrogenated oils. It’s also a good idea to go easy on the trans fats that kids eat, which means cutting back on a lot of high-fat snack foods. Many manufacturers are now cutting trans fats from their products.
Convenience and Processed Foods
Technological advances have dramatically enhanced the quality and increased the range of processed foods. Some critics blame this growing reliance on convenience foods, which are typically high in fat and calories, for the fact that almost one half of all North American adults are overweight. Of these, almost one quarter are obese. The fact is, convenience foods are here to stay; however, anyone who follows the basic rules of variety, moderation, and balance can work them into a healthful, nutritious diet.
Almost everyone consumes some convenience foods, defined as items that require little or no preparation; from ready-to-eat breakfast cereals, canned or frozen goods, to prepackaged heat-and-serve meals. Nutritionally, some of these products do not measure up to home-cooked meals, but this varies greatly among foods. Most convenience foods also tend to contain more sugar, salt and fat than comparable dishes prepared at home.
Processing may strip vitamins and minerals from some foods, but there are exceptions in which convenience foods are actually more nutritious than their fresh counterparts. Vegetables and many fruits harvested and quick-frozen at their peak often have more
vitamins than those picked before maturity, shipped long distances, then allowed to sit on store shelves. Most enriched cereals and breads provide more nutrients than those made with the original grains.
Many food processors have been prompted by consumer demand to enhance the nutritional quality of their products by adding healthful ingredients (for example, calcium to orange juice) or by reducing fat, sugar, and salt. Although some claims of low-fat, no cholesterol, and “lite” may be misleading, an informed shopper who knows how to decipher food labels can make healthful choices.
Many people may worry about the nutritional value of frozen dinners, breakfast bars and other convenience foods. To answer such concerns, many food manufacturers now produce special products. Some of these are low in calories and sodium, while others are designed to meet the special needs of people with nutrition-related problems like diabetes and food allergies. It’s important to check labels and ingredient lists.
Combining convenience foods with fresh ingredients can save both time and money while increasing interest and nutritional value. For example, you can build a tasty and nutritious meal around a frozen entrée by adding a green salad and seasonal vegetables, which take only minutes to prepare but add an assortment of valuable nutrients.
Most parents rely upon at least some convenience items when introducing foods into a baby’s diet. Instant cereals and jars of puréed fruits, vegetables and meats are certainly easier than homemade. More questionable are the convenience foods that many older children seem to prefer. Favourites like hot dogs and cold cuts are usually loaded with fat, salt and preservatives; instant puddings may provide milk, but they are also high in sugar, fats and artificial flavourings and colourings.
When feeding children, emphasize foods made with minimal processing; for example, chicken is a better pick than hot dogs, yogourt is more healthful than puddings, uncoated oat cereals or low-fat granola is a wiser choice than sweetened children’s cereals.
Grilled foods retain a lot of flavour and cooking them doesn’t require added fats. Vegetables cook quickly on the grill with little loss of moisture or vitamins. Grilling—involving direct exposure of food to the source of heat—is the modern, controlled version of man’s oldest culinary technique: roasting over an open fire. The intense flavour of grilled food results from the numerous chemical reactions that take place when a food surface is subjected to very high temperatures. Grilling—whether by gas flame, electric element or charcoal—demands temperatures four to six times higher than can be reached in an oven. Unfortunately, the high heat that causes the appealing caramelization of browning has a less desirable aspect: The outside of the food may become unpalatably charred before the inside is cooked through. Grilling is best reserved, therefore, for quick-cooking foods such as fish and the thinner cuts of meat and poultry. It is an excellent method of preparing vegetables such as eggplant, zucchini, peppers and mushrooms; apples, peaches and other fruits are also delicious when grilled. Preparation requires little more than a light brushing with oil to prevent food from sticking to the grill or drying out, followed by a dusting of herbs. In short, grilling is a truly healthful cooking method—with one potentially major caveat.
Even if there are lots of hungry guests waiting for burgers from the barbecue, don't take them off the grill until they're thoroughly cooked. Ground beef could have come in contact with E. coli, which is present in the intestines of cattle and may infect the meat during processing. Potentially harmful bacteria are killed when the meat is adequately cooked but can survive in meat that is rare. Always cook hamburgers until the juice runs clear and be sure not to place cooked hamburgers back on the same platter that held raw meat.
At grilling temperatures, the surface fat on meat quickly burns away, releasing acrid fumes and creating a risk of fire. There’s a further hazard to grilling. Cancer-causing substances called polycyclic aromatic hydrocarbons form when the fat from meat drips onto hot coals, and are deposited onto the food through smoke. You can minimize exposure to the fumes by partly baking or parboiling the food, then finishing it off with a few minutes on the grill to achieve a crusty exterior and succulent interior. Choose lean cuts and trim all visible fat from meat. Whether you’re using an oven broiler or an outdoor grill, place a broiling pan to catch melted fat under a spatterproof metal shield.
Heating meat, poultry or fish to a high temperature also creates substances called heterocyclic amines (HCAs), which have been linked to cancer in animals. HCAs can also form in foods—especially red meat—that are fried or broiled. This may be one reason that frequent consumption of red meat has been linked, at least in some studies, with an increased risk for certain cancers such as colon cancer.
Other potentially toxic compounds are generated by chemical reactions that take place when foods are cooked at high temperatures. Carcinogenic nitrosamines, for example, form when foods that contain nitrite as a preservative are heated.
There’s no direct evidence that substances causing cancer in animals necessarily cause the disease in humans, but there is enough epidemiological evidence to suggest that foods cooked at a high temperature should be consumed in moderation.
Minimizing your cancer risk
Charcoal-grilling foods, especially fatty meats, can create compounds that are potentially carcinogenic. The factors involved are the charring of the food and the smoke produced when fat drips on the coals, which is then carried back up to the meat. To minimize the risks, take the following steps:
The risks of eating grilled foods can be moderated by combining them with certain protective nutrients. Vitamins C and E, for example, block the chemical reaction that generates nitrosamines. As antioxidants, these vitamins, as well as beta carotene, can neutralize some carcinogens. Wheat bran binds with nitrite and makes it unavailable for nitrosamine formation. So, you can balance your grilled breakfast bacon with a glass of vitamin C-rich citrus juice and fortified whole-grain cereal or a bran muffin for vitamin E.
Substances found in vegetables and fruits bind directly to carcinogens and prevent them from reacting with DNA. Bioflavonoids, the pigments in many fruits and vegetables, appear to block many carcinogens. Fibre may bind with or dilute carcinogens and speed their elimination from the digestive tract. When you barbecue, serve lots of leafy greens and whole grains along with the meat or fish to ensure a healthy mixture of fibre and vitamins. Make a vegetarian barbecue and add low-fat cheese to satisfy a desire for protein. Grilled fruits end a meal with a colourful cocktail of vitamins, fibre and flavour.
• A rich source of beta carotene.
• A good source of vitamins C and B6, folate and potassium.
• Naturally sweet and high in fibre.
Although the two vegetables are unrelated, sweet potatoes are often called yams. Sweet potatoes aren’t in the same family as the common white potato either. But sweet roots are highly nutritious, and their rich flavour belies their humble New World origins.
Like other brightly coloured orange-yellow vegetables, sweet potatoes are an excellent source of beta carotene, an antioxidant. On average, one medium sweet potato provides more than 100 percent of the RDA for vitamin A, about a third of the RDA for vitamin C and B6, 541 milligrams of potassium, along with folate and some iron.
Sweet potatoes also contain plant sterols, compounds that can help lower cholesterol. When eaten with its skin, a sweet potato is an excellent source of soluble and insoluble fibre, which helps reduce cholesterol and may prevent diverticulosis. Beta carotene, the carotenoid that gives colour to sweet potatoes, is a powerful antioxidant linked to lowered risk of heart disease and certain cancers.