Healthy Oils, Healthy Fats

When Americans started to pack on pounds a few decades ago, fat was fingered as public enemy number one. “Low-fat” became the rallying cry for healthy eating. And so began one of the most misguided public health campaigns in history.

Most of us know by now that the main villains are saturated fats, found chiefly in meat and high-fat dairy products, and trans fats, found in fried foods, cakes, crackers, and some margarines. They raise total cholesterol levels and gum up arteries. Unsaturated fats, which mostly come from plants and fish, are essential to good health.

But even the good fat/bad fat message is turning out to be more complicated than nutritionists once thought, as researchers explore the health effects of the many different kinds of fatty acids. With evidence emerging that healthy fats not only improve cholesterol and triglyceride levels but also reduce inflammation, fats are emerging as one of the hottest new functional foods.

Polyunsaturated vs. Monounsaturated: Choosing the Healthiest Oil

“We can now say unequivocally that unsaturated fats protect against heart disease,” says John Brunzell, MD, professor emeritus in the division of metabolism at the University of Washington, Seattle.  

• In an analysis of data from 60 trials, researchers at Maastricht University in the Netherlands found that cutting back on carbohydrates and consuming more polyunsaturated and monounsaturated fats decreases the level of harmful LDL cholesterol and increases protective HDL cholesterol. 
• The more recent Optimal Macronutrient Intake Trial for Heart Health (OmniHeart) study showed that a diet rich in unsaturated fats also lowers blood pressure and reduces overall heart disease risk.

Debates have long raged about whether monounsaturates or polyunsaturates have the edge. The Maastricht University study found a slight advantage to polyunsaturated fats for improving the ratio of HDL (good cholesterol) to total cholesterol. But studies of people with diabetes, who have a high risk of heart disease, conducted at Trinity College in Dublin suggest that monounsaturated fats may offer more protection.

In the end, few of us keep count of grams of monounsaturated or polyunsaturated fat, of course. All edible oils are a blend of these two types of fat. Edible oils also contain at least some saturated fat. The amount of saturated fat in oil may be a more important consideration than the ratio of monos to polys.

• Olive oil, for instance, contains 73% monounsaturated fat, 11% polyunsaturated fat, and 14% saturated fat. 
• Soybean oil, by contrast, is 24% mono, 61% poly, and 15% saturated fat. 
• Canola oil wins high marks. It’s 62% monounaturated, 32% polyunsaturated, and only 6% saturated fat -- by far the lowest among edible oils.

A 2007 study by researchers at the Department of Food Science and Human Nutrition at the University of Illinois, Urbana-Champaign found that substituting canola oil for other vegetable oils and canola oil-based margarine for other spreads could significantly lower saturated fat levels in the American diet. What’s more, canola oil is also a good source of omega-3 polyunsaturated fats, which may be especially crucial to good health.

Of course, studies of the Mediterranean diet suggest that olive oil, which has a very different fatty acid profile, also offers potent protection against heart disease.

“In fact, there are many healthy unsaturated oils,” says Brunzell. “The issue isn’t choosing the healthiest, but encouraging people to use the ones they like.”