How you cook your food is just as important as what you’re choosing to eat. You may be reaching for lean protein and vegetables but your efforts may be cancelled out if they’re thrown into the deep fryer.

“Food has all these nutrients in it like protein, antioxidants, vitamins, polyphenols – our job is to cook these foods to make them safe but we also need to preserve the nutrients the best we can,” Dr. Keith Warriner, a professor at the University of Guelph who heads up the school’s Food Science lab, told Global News.

“When it comes to fruits and vegetables, my biggest thing is to start eating them however you can. Meat is when you want to be more careful about the way you cook because that can change the structure of the product,” Susan Macfarlane, an Ottawa-based registered dietitian, said.

From boiling to deep frying, here’s a look at the best and worst ways to prepare your food for the biggest health benefits.


Believe it or not, raw is best for only certain foods, the experts say. Meat, for example, shouldn’t be eaten raw – for health and safety reasons and because heat can make proteins more available for digestion, Warriner said.

When it comes to vegetables, it depends on what you’re grazing on. If you can stomach raw vegetables, broccoli, cabbage and leafy greens do much better without any heat.

But some vegetables fare better with heat: tomatoes and carrots, for example. They contain lycopene, and cooking makes it easier for your body to easily absorb these phytochemicals.

Boiling or steaming?

When we boil vegetables, we lose vitamins through a few mechanisms: leeching, which goes into the water and through thermal destruction (or heat), Warriner said.

Food is sensitive to heat and degrades depending on how much heat you’re applying and for how long.

“Eating raw cauliflower isn’t the best experience so we have to cook it and the mode of cooking dictates how many vitamins you lose,” Warriner said.

Boiling is the worst way to cook vegetables: “You’re going to lose a lot of the nutrients in the water unless you use it for soup,” he warned.

Boiling has a much longer cook time compared to, say, steaming, which uses less water and helps to retain nutrients.

A 2013 study agreed. When University of Illinois scientists steamed, boiled and stir-fried vegetables, they learned that steaming – at only three to four minutes until vegetables turn into a bright, vibrant colour, is your best bet.

Boiling and microwaving, even just for minutes at a time, didn’t help to retain important vitamins and enzymes.

Boiling vegetables for a long time means losing water-soluble vitamins, such as vitamin C, folate and niacin that end up in the water.

Poaching is also fair game and a safe way to cook your vegetables and meats. Just try not to poach your ingredients in oil or cream – stocks and broths are healthier options.

Stir-frying or sautéing?

Stir-frying and sautéing are fast and convenient ways to put dinner on the table. The key is to keep the stir-frying time to a minimum and try not to use too much heat.

You can also choose an oil with a higher smoke point – they include avocado, almond, corn, canola, grapeseed or peanut oil.

An oil’s smoke point is when the oil burns and smokes when it’s heated to a certain temperature – in the process, all of the healthy nutrients in an oil, such as olive oil, are destroyed.

In some cases, cooking beyond the smoke point can lead to the production of free radicals, which scientists have warned can change or damage DNA.

Macfarlane has a few hacks for stir-frying and sautéing. For starters, you can blanch or steam your vegetables to get some colour, then stir-fry them to finish them off.

“If you’re doing a stir fry, it could be a spaghetti sauce where you add vegetables towards the end,” she explained.

You can add vegetables to soups, sauces and stews without any concern, too.

Roasting or deep frying?

Not surprisingly, the experts are not a fan of the deep fryer. Try not to eat food that is charred or burnt through either of these preparations, the experts say.

“The problem isn’t just nutrient retention, but the generation of hydrocarbons that are cancer-causing. If you overcook meat, especially through roasting, frying and barbecuing, it generates a lot of these compounds,” Warriner warned.

Global health officials have already warned that acrylamide, a substance that’s produced when starchy foods are cooked for too long at high temperatures, is tied to elevated cancer risk. At least, in animal studies.

The WHO’s International Agency for Research on Cancer lists acrylamide as a “probable human carcinogen.”

Let’s not forget that with deep frying, you’re coating your food in oil.

Stick to roasting your meat and vegetables to a light brown colour.

Grilling or barbecuing?

While Canadians love to take to the backyard patio for barbecuing meats, the experts don’t recommend doing it too often.

“Barbecuing is the worst way to cook meat – it’s grilling over an open flame and polyaromatic hydrocarbons are created,” Macfarlane said.

“You’re cooking meat at high temperatures, and the fat drips onto the barbecue and the smoke comes up and coats the meat in these residues,” she explained.

There’s a hack that may help your cause, though: marinate your meat, the experts say. (Warriner says a dark beer, such as a stout ale are good options.)

“The theory goes that compounds in dark beer, they neutralize the hydrocarbons,” he explained.

Bake your ingredients in the oven first, then finish them on the grill, Macfarlane suggests.

“Don’t pierce the meat because drippings are something you want to avoid, and use tongs to turn the food so one side isn’t getting overcooked,” she said.