Ask the Diet Doctor: How Cooking Affects Omega 3s
Q: Does cooking fish destroy the benefits of the omega-3 fats?
A: Fortunately it's unlikely. Rich in protein and long-chain omega-3 fats EPA and DHA, fatty fish like salmon are often considered superfoods. Population-based studies show that eating more fish is generally associated with a longer life and less chronic disease, and EPA and DHA fats have been associated with a slower rate of chromosome aging.
But there's a dark side of these healthy fats: oxidation. The more "unsaturated" the chemical structure of a fat is, the greater likelihood the fat will be oxidized, and EPA and DHA are highly unsaturated and thus some of the most susceptible for oxidation. Oxidized fats lead to the formation of advanced lipid oxidation endproducts (ALEs), nasty biochemical mercenaries that are responsible for increasing risk of just about every disease you can imagine.
So does cooking a piece of salmon turn it from an uber-health food to a cancer-promoting entrée? Luckily no. Mother Nature is pretty slick and has surrounded the volatile EPA and DHA with their own nutritional secret service team to fight oxidation.
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The layers of protection are two-fold. First, there is the food matrix, a term scientists use to describe the components of a food that surround the nutrient of focus. When you cook a piece of fish you aren't just cooking the oil-the oil is interwoven with proteins and other parts of the food structure that give the fish its taste and texture. The food matrix also helps prevent oxidation of these precious fats. The second layer of protection are antioxidants like beta-carotene, which provide damage control by quenching free radicals from oxidized fats as they are formed.
These layers of nutritional protection aren't just theoretical. Several studies show that you can cook salmon a variety of ways without any significant increase in oxidized fats. Research published in Food Chemistry found no differences in fatty acid composition when salmon was raw, poached, steamed, microwaved, pan fried, or baked.
And a 2004 study in the Journal of Agriculture and Food Chemistry found that neither pan-frying for six minutes nor steaming for 12 minutes led to acceleration in lipid oxidation. The scientists did find that steaming the salmon lead to a greater formation of cholesterol oxidation products (COPs), which they attributed to the longer duration of cooking, not necessarily the process of steaming the salmon. You can further reduce the formation of COPs by seasoning your fish with herbs and spices. They not only add flavor, but also are a powerful source of antioxidants, which further lower the risk of oxidized fats or cholesterol.