Wellness Food Trends: Which Oils And Fats Are Healthy And Why?
A lesson on oils, fats and how nothing is what it seems anymore.
By Mark Anthony, Ph.D., Technical Editor | 03/29/2011
Back when "fat made you fat," we looked at fats and oils from the perspective of calories and cholesterol. All carried a calorie load of nine per gram, more than twice that of protein and carbs. Then we bifurcated fats into opposing categories: "good" oils that purportedly lowered cholesterol, and "bad" fats (including tropical fats) that supposedly raised it.
A decade of this oversimplification led to these things called essential fatty acids entering the vernacular — even though most people didn't know what fatty acids were, exactly. From there, two events focused our attention on the finer details of fats and oils: The revelation that trans fatty acids were a serious health risk, and research into the benefits of omega-3 fatty acids.
Fatty acids give different fats their unique properties. Each is a modified chain of carbon atoms, generally 8-22 carbons long. Attach any three chains together at one end using a connector and you have a triglyceride. Triglycerides make up 95 percent of dietary fat. (Picture three pipe cleaners bound together at one end and free to move at the other.) Fatty acid chains are either "saturated" (all carbon atoms bound to another element, typically a hydrogen, causing the fully loaded molecule to be straight) or "unsaturated" (some carbon atoms left with an "available" place to bond or double-bond another element, causing the molecule to be kinked).
Monounsaturated fatty acids have one kink, and polyunsaturated fatty acids have many. The location of the kink determines the class.
Omega-3 and omega-6 are two main classes of polyunsaturated fatty acids. They're considered essential because our bodies can't make them. Kinked fatty acids occupy more space than the straight ones and thus stay more fluid at lower temperatures. Since straight chain (saturated) fatty acids pack together nicely, they make for flakier pie crusts and crispier chips.
Does the "saturated = bad, unsaturated = good" paradigm really apply? Trans fatty acids are a partially hydrogenated byproduct of converting unsaturated fatty acids to saturated. They started out as a health solution only to become the 21st century's first evil ingredient. As it happens, the question is more complicated. Take coconut oil. Is it unhealthy because it's saturated? An important fatty acid in coconut oil is lauric acid, a 12-carbon, medium-chain saturated fat. Lauric acid's effect on cholesterol is a little muddled. It may increase "bad" LDLs, but also "good" HDLs, but the evidence is not there for linking coconut oil to disease and, in fact, other studies show strong positive health benefits to it. Organic coconut oil has become a trendy way to fill the baking gap left by the absence of fats rich in trans fatty acids, where flakiness is prized. Palm oil, similar to coconut oil, also has shown evidence of defying the "all saturated fats are unhealthy" paradigm.
Coconut oil not your thing? Years ago it was shown that during digestion much of stearic acid, an 18-carbon saturated fatty acid prominent in beef fat, is converted to oleic acid, the unsaturated fatty acid dominant in olive oil (call it "stearic acid with a kink"), and so beef fat tended not to raise blood cholesterol. But what do you do with that information? Develop soybeans rich in stearic acid, and you may have a saturated-fat alternative to trans fatty acids. And now stearic-rich soybean oil is a marketed product.
Interested in a new source of omega-3 fatty acids, beyond fish, walnuts and flax? Cranberry seed oil sports both omega-3 and omega-6 fatty acids, along with a generous supply of oleic acid. "OmegaCran oil offers many of the benefits from omega-3 and omega-6 fatty acids, but does not have the odor or taste of fish oil," notes Dan Souza, senior director of marketing for Decas Botanical Synergies, Carver, Mass.
All the rage now are the omega 3s EPA and DHA from salmon and other cold-water fish. These are not the same as plant-based omegas; they are longer (20- and 22-carbon fatty acids, respectively) with lots of kinks. Those extra kinks are adaptations to cold weather, allowing the fatty acids in membranes (phospholipids) to take up more space and keep from freezing during the cold.
It's no surprise that the truth about fats and oils in relation to health turns out to be a far more complicated story than presented at first. The challenge to processors, however, will be two-fold. First, focusing on the reliable current science to know what the legitimate health aspects are of a particular oil or fat. Second, employing the marketing tactics necessary to cut through the decades of flaky information and keep consumers from avoiding a perfectly good, even health-supporting product because it happens to be made with coconut or palm oil.