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Palm and coconut oils are discovering new popularity, even among those who once maligned them nutritionists. But is it all just a flash in the pan? We dig into the research.

Tropical oils were once the favored fats for processed foods. Palm and coconut oil, for instance, had good shelf stability, creamy texture, and other features desired by food manufacturers. But starting in the late 1980s, these oils fell out of favor because of their saturated fats, which were linked to elevated blood cholesterol. The solution, at the time, was to replace them with partially hydrogenated vegetable oils (margarine, dalda) which have similar qualities as tropical oils. Partially hydrogenated oils became ubiquitous in processed foods - until it was discovered that the trans fats they contain are even worse for the heart than tropical oils. The latest solution? Some manufacturers have been turning (or returning) to tropical oils, touting them as a healthier alternative to partially hydrogenated oils. You'll find them in an increasing number of packaged foods, including crackers, cookies, pie crusts, energy bars, and bread spreads, as well as in microwave and movie theatre popcorn. Is this a wise move?

UNFILTERED FACTS Before you get to the cup cakes, let's start with the science. All fats are mixtures of saturated and unsaturated (poly- and monounsaturated)

Palm Reading

• Palm oil, from the palm fruit, is about 50% saturated fat and fairly high in monounsaturated fats. Crude palm oil contains vitamin E, carotenoids, and other antioxidants. Refining the oil, however, reduces or eliminates these substances. • Palm kernel oil, from the palm seed, is closer in composition to coconut oil than to palm oil. It is more saturated (about 80%), contains little monounsaturated fat, and often undergoes harsher chemical processing than palm oil. • Fractionated palm kernel oil is made by further processing palm kernel oil to remove the liquid portion, leaving behind even more saturated solids. This oil is often used in energy bars, for example, where it makes the coatings less likely to melt. It's unknown if it is any better for you than partially hydrogenated oils.

fatty acids. Though most of the fatty acids in tropical oils are saturated, not all saturated fats are harmful. Palm oil also contains a fair amount of monounsaturated fats.

• Some lab research suggests that palm oil, though highly saturated, may act more like healthful unsaturated fats in the body, in terms of its main fatty acid, palmitic acid's effects on blood cholesterol. But the evidence is conflicting, and the few clinical studies have been small. One study from Brazil in 2008, for example, found that palm oil improved cholesterol and triglycerides in healthy people, with women benefiting most. In contrast, a study last year from Thailand found it increased cholesterol in women who already had high cholesterol. Meanwhile, population studies have not consistently linked consumption of palm oil to heart disease.

• Published research on coconut oil is even more scant. Though coconut oil is highly saturated, its fats seem to be neutral overall-that is, they don't worsen or improve cholesterol levels in most people. In one recent study, in the journal Lipids, women who consumed about 25 ml of coconut oil a day for 12 weeks had no undesirable changes in cholesterol. And in places where people consume a lot of coconut oil, such as Sri Lanka and Polynesia, cholesterol levels tend to be low.

• More good news: Fat in the diet, whether it's saturated or unsaturated, tends to nudge good HDL cholesterol levels up, but coconut oil seems to be especially potent at doing so. Saturated fat is divided into various types, based on the number of carbon atoms in the molecule, and about half of the saturated fat in coconut oil is the 12-carbon variety, called lauric acid. Researchers believe lauric acid is probably responsible for the unusual HDL effects of coconut oil.

• Any number of health claims have been made for lauric acid. According to proponents, it's a wonder substance with possible antibacterial, antimicrobial, antiviral properties that could strengthen immunity, improve digestion, prevent heart disease, arthritis, and other chronic diseases. In theory, lauric acid may even combat H.I.V., clear up acne and speed up your metabolism, they say. Researchers are skeptical. "There are a lot of claims that coconut oil may have health benefits, but there is no concrete scientific data yet to support this," says Dr. Daniel Hwang, a research molecular biologist specializing in lauric acid at the Western Human Nutrition Research Center at the University of California, Davis.

JUST THE NUMBERS Coconut oil is about 90% saturated fat, which is a higher percentage than butter (about 64% saturated fat), beef fat (40%), or even lard (also 40%).

• It is true however that due to coconut oil's chemical structure, it takes a few more calories for the body to process the oil, compared to other fat. But any calorie-burning effect would be minimal at best. It is certainly no treatment for obesity.

THE DOPE ON VIRGIN COCONUT OIL

According to Thomas Brenna, a professor of nutritional sciences at Cornell University who has extensively reviewed the literature on coconut oil, a considerable part of the stigma against coconut oil can be traced to one major factor: "Most of the studies involving coconut oil were done with partially hydrogenated coconut oil, which researchers used because they needed to raise the cholesterol levels of their rabbits in order to collect certain data," Dr. Brenna says. "Virgin coconut oil, which has not been chemically treated, is a different thing in terms of a health risk perspective. And maybe it isn't so bad for you after all." Virgin coconut oil has a deep coconut flavor with hints of a haunting nutty, vanilla note that persists even after cooking. It's even milder and richer tasting than butter, sweet and light textured and without any of the bitterness you get in olive oil. Refined coconut oil, which has been processed enough to raise the temperature at which it begins to smoke, lacks the same coconut profundity, but works better for stir- and deep-frying. Cooking with coconut oil.

• Melted and cooled, virgin coconut oil's natural sweetness works beautifully in poundcake, yielding a loaf with a tight, golden crumb and gentle coconut fragrance that may be enhanced with lime zest, almonds and a grating of fresh nutmeg.

• Coconut oil is also great for sautéing vegetables and is particularly wonderful paired with bitter greens, which soften and mellow under the oil's gentle touch. And aromatics, especially onions, absorb the sweetness of the oil and pass that lovely nuance on to a whole dish of say plump, juicy prawns spiked with garlic, ginger and coriander.

• Roasting sweet potatoes in coconut oil enhances their caramelized flavor while adding a delicate coconut essence.

• Coconut oil also brings out the nutty sweetness of popcorn while adding a rich creamy sensation, without having to pour melted butter on the top.

THE TAKE-HOME MESSAGE Plant-based oils are more than just fats. They contain many antioxidants and other substances, so their overall effects on health can't be predicted just by the changes in LDL and HDL. In addition how the oils are processed may matter: Partial hydrogenation of coconut oil creates the dreaded trans fats and also destroys many of the good essential fatty acids, antioxidants and other positive components present in it. Virgin coconut oil, on the other hand, is a healthier option.

Our advice: As we discussed in an earlier issue, just because a food is high in saturated fat doesn't necessarily mean it increases blood cholesterol or contributes to heart disease. The effect of saturated fat varies from person to person, depending on genetics, weight, other dietary and lifestyle factors, and even gender (saturated fat tends to increase LDL, the "bad" cholesterol, more in men). It seems safe to say that if you eat it just once in a while, coconut oil probably isn't going to give you a heart attack, make you thinner or ward off the flu. You can use coconut oil in cooking on occasion if you like the flavor, though we recommend vegetable oils such as groundnut, mustard, sesame, olive, soy, or safflower, which are mainly unsaturated fat and therefore both lower LDL and increase HDL, for regular use. You should still limit snack foods that contain these oils which tend to be high in calories and low in nutrients anyway. But coconut, which is rich in fibre, vitamins and other antioxidants, is good food, in moderation.