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When It Comes to Omega-3s, Not All Fish Are Created Equal

An ever-increasing number of health organizations are telling us to include fish in our diet as a source of omega-3 fats, and now there is research to show that the fish we choose can make a significant difference in our health outcome. Researchers based at the University of Washington in Seattle, Washington looked at blood levels of two key omega-3 fatty acids-EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid)-in 900 study participants who regularly consumed fish but were known not to be taking fish oil supplements of any kind. Adults in the study were participants in the Multi-Ethnic Study of Atherosclerosis (MESA), a large-scale study involving men and women across the United States, and in this study of omega-3 fats, averaging 59 years of age. As expected, participants with higher levels of EPA in their blood also tended to have higher levels of DHA. On average, the participants were found to consume about 1.5 servings of non-fried fish and shellfish each week, and about 1 additional serving of either fried fish or fish incorporated into some other kind of mixed entrée. Overall, the researchers estimated an average of 2.4 total fish servings per week for the group as a whole.

Interestingly, total fish consumption was not strongly associated with levels of EPA and DHA in the blood of the participants, and to get a strong association between omega-3s in the blood and fish intake, the researchers had to limit their analysis to non-fried fish only. In other words, when it came to explaining higher levels of omega-3 fats in the blood, fried fish were out, and non-fried fish were in! It took at least 2 servings of non-fried fish per week to produce this connection between omega-3s in the blood and fish intake, but bumping up this average to 3 servings of non-fried fish did not seem to make much difference in the blood omega-3s.

The authors speculated about possible reasons for the favorable results connected with non-fried fish. First, they wondered whether the fish being chosen for frying were simply lower in omega-3s than the non-fried fish. For example, they pointed out that catfish and shrimp are often consumed in fried form, but salmon are hardly ever consumed in fried form. Second, they hypothesized that frying itself-because it almost always involves a vegetable oil with high levels of omega-6 fats and because the high heat almost always destroys delicate fats like omega-3s-may be a key culprit in the poor results obtained with analysis of fried foods.

At the World's Healthiest Foods, it's not just fish frying that we always avoid-it's any unnecessary high-heat cooking. Nor do we recommend heating of any delicate oil, for precisely the reasons described in this University of Washington study. We also encourage deliberate selection of high omega-3 fish, especially wild-caught Pacific salmon, as a way to increase your omega-3 intake. This study provides evidence that such an approach can really work to increase levels of EPA and DHA in your body that are critical for so many aspects of your health.

Practical Tip

While many organizations will tell you to substitute fish for meat in your diet, don't treat all fish as created equal. Focus on high omega-3 fish like wild-caught Pacific salmon, and avoid fried fish not only because of the heat damage to your fish but also because omega-6 fats in your frying oil may partly offset the value of your fish's omega-3s. Two non-fried, omega-3 fish servings per week may be enough for improving levels of omega-3s in your bloodstream!