Not all fats are created equal.
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Fanny packs and shoulder cut-outs may be back in—but fortunately, the fat-phobic diet of the '80s remains out of style. Health experts now largely agree we need more of this macronutrient in our lives than SnackWell's cookies and fat-free pudding cups once provided. Fats help your body absorb nutrients, provide energy, and make food more satisfying (not to mention tasty). But as a recent found of health headlines about coconut oil—which, depending on who you ask, is awesome or awful—makes clear, they're still debating exactly how much and what kind.
Oils from nuts, seeds, and vegetables contain three main types of fats—saturated, monounsaturated, and polyunsaturated—in various ratios. So how do you know which bottle to reach for when you just want to scramble an egg, dress a salad, or stir-fry some green beans?
Well, first of all, congratulate yourself on even stepping into the kitchen—one thing almost every study and nutrition expert will tell you is that home-prepared meals tend to be more nutritious than restaurant or take-out grub.
From there, choose olive oil or just about any kind of non-tropical vegetable or nut oil, including avocado, canola, walnut, or peanut, recommends New York-based dietitian and chef Abbie Gellman. While each has a slightly different nutrient profile, Gellman says she rarely dictates the use of one over the other in meal plans she creates, unless a client has a serious illness that requires a plan that's highly specific. In most cases, the best oil for the occasion depends more on things like how you're using it, flavor preferences, and cost, she says. Here's some guidance to bake, sauté, or fry by.
Tropical oils: Coconut, palm, and palm kernel oil
They might taste like a beach vacation, but these oils contain high levels of saturated fats (coconut oil, in particular, has 11 grams or more per tablespoon). A new American Heart Association presidential advisory—the scientific communication that launched a million coconut-oil takes—reviews the available research and recommends replacing saturated fats with poly- or monounsaturated versions to improve heart health.
The main mechanism involves reducing blood levels of LDL or "bad" cholesterol by speeding up the rate at which your body can break down this waxy, artery-clogging substance. That is, of course, "if you accept the premise that LDL cholesterol levels are a risk factor for cardiovascular disease, which most people do," says Alice Lichtenstein, director of the Cardiovascular Nutrition Laboratory at Tufts University and one of the authors of the AHA advisory.
But most doesn't mean all. Dissenters to the AHA's philosophy include several investigative journalists, as well as three cardiologists who wrote an editorial this summer in the British Journal of Sports Medicine that comes to a largely opposite conclusion. Saturated fat, these doctors say, doesn't deserve the bad rap—and LDL cholesterol has been overemphasized as a cause of heart disease. Factors like inflammation and insulin resistance, a precursor to diabetes, deserve more of the blame. As evidence they, point to meta-analyses that don't align with the AHA's guidance.
Some of this disagreement can be traced back to the inherent difficulties of studying nutrition—randomized controlled trials, the gold standard of medical research, are more difficult to conduct when you're changing the way people eat rather than simply asking them to take a pill or placebo, Lichtenstein says. And if you want to know about diet's effects on a health outcome like heart disease, you have to study people for years, decades even.
Rita Redberg, a cardiologist at the University of California—San Francisco and one of the authors of the BJSM editorial, says conflicts of interest may also be at play. For instance, JAMA Internal Medicine—the journal for which she serves as editor—last year published a paper showing sugar industry influence may have affected the dissemination of research, burying results implicating sugar in cardiovascular disease while overplaying fat's role.
Another factor: Saturated fats may behave differently in some foods than others. Keith Ayoob, associate clinical professor at the Albert Einstein College of Medicine, cites a recent meta-analysis that found people who ate full-fat cheeses had lower LDL and higher levels of HDL or "good" cholesterol than those who consumed butter instead.
However, he remains unconvinced that coconut oil specifically has any redeeming qualities. A roundup of the research in Nutrition Reviews found that, while native populations who eat coconut foods don't seem to experience adverse effects on their hearts, there's no evidence the same would be true if you piled them on top of traditional Western diets.
In his own diet and in his nutrition practice, Ayoob steers clear of tropical oils. Gellman says she'll use coconut oil sparingly—largely when she's baking for vegans, who lack other sources of saturated fats. She's seen many clients with a meat-heavy, paleo-type diet add coconut oils on top and watch their cholesterol levels shoot through the roof. That highlights another big factor in applying nutrition research to your own life, she says: Rather than just focusing on whether one food is "good" or "bad," you have to take into account your overall dietary pattern.
Unlike the relatively contentious coconut oil, olive oil enjoys widespread kudos from health experts. In one large, often-cited randomized controlled trial published in the New England Journal of Medicine, a Mediterranean diet supplemented with four or more tablespoons of the stuff daily cut the risk of cardiovascular events by 30 percent over about five years.
And a meta-analysis published last year suggest olive oil both reduces the risk of type 2 diabetes and promotes better blood glucose control in those who already have the condition.
Researchers credit monounsaturated fats, which appear to control cholesterol and increase your body's ability to use insulin to control blood sugar. Extra virgin olive oil also contains antioxidants called polyphenols that further reduce inflammation, potentially preventing heart disease and other conditions, Ayoob says.
Olive oil, especially extra virgin types, has a lower smoke point than many vegetable oils—that means it breaks down at the high temperatures used for broiling, frying, or grilling, creating potentially harmful compounds (not to mention a funky flavor), Gellman says. But it's great for sautéing over medium heat, tossing in salad dressing, and drizzling over a finished dish.
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Other vegetable and nut oils
Oils made from other plants, nuts, and seeds range from the cheap and easily available—canola and corn—to the more expensive and exotic, such as avocado and macadamia nut oil.
Corn, canola, and peanut oil are particularly high in polyunsaturated fatty acids, which shuttle LDL cholesterol out of your system and increase levels of HDL or "good" cholesterol. Even those who remain skeptical of LDL's importance tend to view HDL as a marker of good heart health, perhaps because it's also linked to lower levels of inflammation.
Oils with the highest smoke points—best for high-heat cooking—include avocado, sunflower, safflower, sesame, and soybean, Gellman says. Like olive oil, canola and grapeseed have slightly lower smoke points, making them ideal for cooking at medium-high or medium heat.
Walnut and flaxseed oils contain essential fatty acids—compounds called linoleic acid and alpha-linoleic acid your body needs but can't produce (though in less accessible formulations than fatty fish and fish oil, Ayoob notes). But they break down so easily you should use them only for salad dressings or cold sauces (and store them in the fridge), Gellman says.
From there, it's a matter of taste: "Nobody's going to give you a dish of canola oil to dip your bread into," Ayoob says. However, its neutral profile works better in many baked dishes than the distinct savoriness of olive oil, making it his second go-to in the kitchen. Meanwhile, sesame oil has a particularly strong flavor often used in Asian dishes. "A little bit goes a long way," he says.
Whether you buy an aerosol can or fill an olive-oil spritzer, these products contain the same fats as liquid oils, Gellman says. Even those labeled "cooking spray" or "grilling spray" will reveal their contents—for instance, canola oil, corn oil, or a blend—in the ingredients list.
The spray simply offers a way to distribute oil more evenly, Ayoob says. This can help keep food from sticking to pans or muffin tins, and also might keep your calorie count under control if you're dressing salads or tossing pasta.
And that's important, too, he notes. Regardless of their nutritious merit, oils like olive oil will cause you to gain weight if you use them by the vat, and that places excess strain on your heart. "Even if you're consuming a healthy diet, it has to be within an appropriate calorie amount or you're going to wipe out the benefits of that healthy diet," Lichtenstein agrees.
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