Choice Nutrition's Dr. Evan McCarvill (view biography) explains little known facts and sheds light on some myths, helping YOU to prepare safe and healthy meals for your family!
In clinical practice, I frequently harp on the virtues of a Whole Foods Plant-based Diet. That is, a "vegetarian" diet, but with nutritionally adequate amounts of healthy animal protein included. That's the perspective. For most people in the West, this entails cutting down their protein intake to roughly 55-60 grams per day (the amount in a typical chicken breast), as well as their intake of simple carbohydrates, and significantly increasing the amount of unprocessed fruits and vegetables in their diet. It also usually entails taking more time to prepare and cook your foods, rather than relying on pre-packaged "quick and easy" starting points. This is also largely in line with what is called the "Mediterranean diet"; a diet that has been extensively studied for it's anti-inflammatory and cardio-protective benefits.
But it isn't just WHAT you eat that's important, as important as it is. There is also HOW you prepare what you eat. Some methods of cooking and preparation are better than others for your health. Today, we're going to break them down.
Let's Start with the BAD :)
You'll find a common theme with these "bad" cooking methods is that they usually entail DRY and HIGH HEAT conditions. These conditions allow for denaturing of proteins and sometimes destruction of certain vitamins and minerals. But most critically, they allow for the chemical reactions that combine protein molecules with fat and reducing sugar molecules, creating denatured hybrid molecules called "Advanced Glycation End products", or AGEs. The creation of AGEs is actually visible during the "browning" reaction that is observed during certain kinds of cooking. It's also known as the Maillard reaction. It's what gives bread it's hard brown outer crust, for instance. AGE formation is especially great in animal-derived foods that are high in fat and protein.
These AGE molecules, if they get into your body through your diet, will bind with what are known as AGE Receptors (or "RAGEs"), triggering the release of pro-inflammatory cytokines (cell signals) in the body, contributing to chronic inflammation. Chronic inflammation is probably the biggest common factor to a variety of chronic degenerative conditions, such as heart disease, arthritis, diabetes, and cancer risk. So a good rule of thumb to avoid these inflammatory factors, is to avoid DRY and HIGH HEAT cooking methods.
I'm sure this goes without saying for this audience, but frying food in oil is not the best cooking method. It substantially increases the caloric content of the food, and contributes to obesity. A report from Statistics Canada in 2015 indicated that 20.2% of Canadian adults are obese. That's up from 15% in 2003. Don't be a statistic.
Foods fried in oil will absorb the saturated fatty acids, adding unnecessary calories. For instance, a baked potato has 161 calories and less than 1 g of fat, while one medium serving of restaurant French fries may contain 453 calories and 23 g of fat. Same goes for drenching vegetables in butter or adding butter to baked or grilled meats. A diet high in trans fat, saturated fats and sodium can lead to increased blood pressure, as well as increased risk of coronary heart disease and stroke.
BROILING / ROASTING
Broiling and roasting entail exposing the food to direct heat in an electric or gas oven. Again, we are talking about DRY and very HOT conditions. As such, such cooking methods should be used sparingly, given the AGE concerns noted above. In the case of Broiling, it may not be so bad in the sense that it involves exposure to high heat for a relatively short period of time, cooking the outside of the food/meat, while leaving the interior tender. These shorter cooking times allow for less time for AGEs to form. However, this is also why it is very important to use lean cuts of meat, and to cut away any excess fat before cooking! Broiling and roasting might not be the best method for cooking vegetables, as they tend to dry out more readily.
GRILLING / BBQ'ing
People love grilling and barbecuing. Overall, it's certainly healthier than frying or deep frying, and brings a desirable "smoky" flavor to the finished product (That's the delicious taste of AGEs, btw). However, some research shows that regular consumption of charred or well-done meat can increase the risk of pancreatic, breast, and colon cancer. I'm not saying never use these cooking methods, but be aware of the carcinogenic potential of foods blackened by dry heat, and use sparingly. Also, once again, it is important to stick with lean cuts of meat, remove excess fat, minimize cooking time, and NEVER apply barbecue sauce until AFTER you have finished cooking the meat.
NOW LET's LEARN ABOUT THE GOOD!!
In contrast to the common theme of the "bad" cooking methods, you will find among the "good" cooking methods, a common theme of WET and LOW HEAT. Lower heat, as well as moisture, interferes with the chemical reaction that creates the AGEs that can be so detrimental.
Boiling is a simple and quick cooking method, requiring nothing but water, a bit of salt, and a good pot. While there is some concern about leaching out and washing away a large portion of a food's vitamin and mineral content, some research actually suggests that boiling could be the best way to preserve nutrients in such vegetables as carrots, zucchini, and broccoli.
Then there is boiling's cousin, poaching. By always using water as the carrier of heat into your food, you ensure that the temperature never exceeds 100 degrees Celsius, as this is the maximum temperature of liquid water at normal atmospheric pressure. Poaching entails simmering the food in a small amount of hot water, at just below the boiling point. It takes a bit longer than boiling, but is a great way to cook delicate foods such as fish, eggs, or fruit.
Cooking food in an enclosed environment infused with steam is the essence of the steaming process. You can accomplish this in a number of ways; such as with a covered and perforated basket that rests above a pot of boiling water; with parchment wrapper or foil; with Chinese bamboo steamers that stack on top of a wok; or with dedicated electric steamers. Steaming cooks while sealing in flavor and nutrients. In fact, it preserves nutrients better than most cooking methods, except for microwaving.
Believe it or not, I've come across some disconcerting myths in "alternative" circles that microwaving is somehow a detrimental cooking method. There's this intuitive distrust that people seem to have of using "radiation" of any sort to cook your food; the suggestion being that it "deadens" the food somehow (whatever that even means....). I can assure you that this just isn't so. In fact, "nuking" your food may be one of the healthiest methods. By sending microwave photons into the food, it excites the molecules and causes them to vibrate faster, which basically means it heats the food from the inside out. It essentially amounts to steaming the food. Microwaving allows for short cooking times, which does wonders for minimizing nutrient destruction. While this method can sometimes cause the food to dry out, you can usually prevent this by splashing the item with a bit of water, or by laying a wet paper towel over the top of the dish. You can microwave just about anything, from vegetables, to rice, to meat or eggs. One legitimate concern about microwaving is the possibility of leaching toxic chemicals into the food, if you place the food in a plastic container that is not approved for microwave use. Don't do that. If in doubt, use glass or ceramic containers that are microwave-safe. Aside from that, microwaving is an excellent choice.
The essence of stir-frying is cooking at high heat for a very short time. Similar to broiling, because the food is cooked quickly, it helps to preserve nutrients. The short cooking time requires the food be cut into small, uniformly bite-size pieces, to ensure every ingredient is cooked thoroughly. Ideal foods would be bit-sized pieces of meat, grains such as rice or quinoa, as well as thinly cut vegetables such as bell peppers, carrots, and snow peas. While this method does require some oil in the pan, it should only be a moderate amount; just enough to get a nice sear going. I also like to sprinkle a bit of water in there too, to keep the moisture up, again, to prevent the formation of AGEs. The wok, with its broad sloping sides, is the ideal tool for stir-frying.
This method requires very little water and time to accomplish. Because of the increased pressure within the sealed chamber, the water is able to achieve temperatures above the regular boiling temperature at normal atmospheric pressure. This is what allows for the shorter cooking time, which in turn helps to preserve nutrients. Soups and stews that might otherwise take hours to simmer can be ready in 15-30 minutes. In fact, you can take this as something of an addendum to last month's article on bone broth. By combining the high-pressure heat with a still somewhat lengthy cooking time (but still much shorter than with regular boiling) you can produce a very rich bone broth very quickly with a pressure cooker.
NO COOKING!! - EAT RAW FOODS
There has been much advocacy for raw foods diets recently, and for good reason. Many studies do indeed show that there are benefits to incorporating more raw food into the diet, and that "eating the rainbow", with lots of dark green, purples, and oranges, consistently reduces the risk of cancer, due to the increased anti-inflammatory and anti-oxidant benefits. However, there is still some debate whether raw foods are the best overall. Cooking can actually help break down food in preparation for digestion, and enhance the absorption of nutrients, such as lycopene from tomatoes, as well as anti-oxidants from carrots, spinach, sweet potatoes, and peppers. I will often favour cooked foods for this reason, and to make the job of digestion easier for people dealing with gas and bloating or irritable bowel. But certainly incorporating raw foods into your diet can be a viable and healthy option in many cases.
So there you have it. Hopefully this gives you some ideas on how you might change or optimize your cooking methods in the future for your favourite foods.