They called it Formula 47 in the US, after the total cost in cents of a burger, fries and milk shake in 1960. Formula 47 was a blend of rendered beef fat and vegetable oil, which, when used to fry shoestring slices of Russet Burbank potatoes, imparted a flavour so rich and appetising that it helped McDonald's, the restaurant selling the fries, to become the world's dominant fast-food chain. But that story turned into a cautionary tale whose lessons extend into the home kitchen. Health advocates blamed Formula 47 fries for raising customers' cholesterol, so in 1990 the Golden Arches switched to what people assumed was healthier - 100 per cent vegetable oil. The new oils were good fats that had been altered - hydrogenated - for flavour retention and longer shelf life. But that made them even more damaging to cardiovascular health than the saturated fats had been thought to be.
Some public-health experts now blame the trans fats in hydrogenated oils for tens of thousands of premature deaths. According to a recent study review by the Harvard School of Public Health, trans fats may increase your risk of a host of chronic diseases and also promote weight gain. So McDonald's and others have once again reformulated their oil, using vegetable-oil blends that are free of trans fats.
In short, oils aren't as simple as they seem. If you cook with the wrong oil, you may be sabotaging your health. To protect your body, ease your mind, and please your palate, follow these rules.
Don't rely on vegetable oil
Corn, soybean, and other vegetable oils have high levels of omega-6 fats. These polyunsaturated fats aren't bad when they're balanced with plenty of omega-3 fatty acids, such as those found in abundance in oily fish such as salmon and mackerel. But that often isn't the case in the typical western diet, though active people tend to have fairly healthy diets. "We now consume 20:1 omega-6 fats to omega-3s," says Jonny Bowden, author of The 150 Healthiest Foods on Earth. "Our inflammatory factory is overstaffed, and our anti-inflammatory factory is understaffed."
A high intake of omega-6 fats relative to omega-3 fats increases inflammation, which may increase your risk of heart disease, diabetes, and cancer, according to a 2008 review of studies by the US Center for Genetics, Nutrition and Health. There are plenty of other choices.
Expand your tastes
Not all fats are created equal. Experts say the most nutritious way to go is with a few different cooking oils to help balance your intake of omega-3 and omega-6 polyunsaturated fats, as well as saturated and monounsaturated fats. "Old Mediterranean cultures had olive oil on salad, fish at night, and then cow or goat butter or cheese, and they were more or less accidentally coming up with the one-to-one-to-one ratio," says KC Hayes, a fats researcher at Brandeis University, in Massachusetts.
Here's an easy way to balance your diet: match fats to the cuisine you're cooking. If you're making a spaghetti sauce from scratch, use a drizzle of olive oil to sauté the onions. Try coconut or peanut oil when you're whipping up an Asian stir-fry. Start an omelette by melting a little butter. The greater the variety of nonhydrogenated fats you incorporate into your diet, the better. A moderate intake of all types of nonhydrogenated fat is best, according to the American Heart Association.
You can access more nutrition advice in the full article (subscriber-only). Subscribe online now to access all our premium online content and make a significant saving on the newsstand magazine price.