Omega-3 fatty acids in fish from the Great Lakes subject of new journal article

Scientists from the US and Canada have found Great Lakes siscowet lake trout to be high in good fatty acids, possibly due to colder temperatures of northern waters.

Ron Kinnunen of Michigan Sea Grant recently coauthored a paper with scientists from Concordia University, University of Guelph, and the Inter-tribal Fisheries Assessment Program titled, “Omega-3 Fatty Acids in Fish from the Laurentian Great Lakes Tribal Fisheries” that has been accepted for publication in the Journal of Human and Ecological Risk Assessment.

Today, most western diets have a very low omega 3/6 ratio (polyunsaturated/saturated fats) and this imbalance has contributed toward many chronic diseases such as cardiovascular disease. The omega 3/6 ratio of fatty acids in fish can be an important nutritional indicator. To restore balance in an imbalanced diet may require incorporating more foods with an omega 3/6 ratio above 1:1. These polyunsaturated fats unique to some fish are better in our diets compared to the saturated fats, which we tend to get too much of in a western diet. Total omega-3 fatty acids in siscowet lake trout was found to be 2.31 times greater than total omega-6. Additionally, siscowet lake trout compare favorably to other lipid reports and are well above the targeted omega 3/6 ratio of 1:1.

Because fish are a good source of omega-3 fatty acids, nutritionists recommend an intake of two servings of fatty fish per week. This is equivalent to 450-500 mg of EPA and DHA per day, for primary prevention of coronary heart disease. EPA and DHA are the unique fatty acids found in fish oil. Using a serving size of 3 ounces and data from Lake Superior siscowet lake trout (with the skin off), to meet 3500 mg of combined EPA and DHA per week (from fish alone), the average person would need to consume 3.15 servings per week.

It was found that siscowet lake trout, and several other species of the Great Lakes fish, possess high levels of omega-3 fatty acids. Although these are freshwater fish, it is believed that one possible reason for elevated polyunsaturated fatty acids is that cold temperate latitudes are apparently selective for production of more polyunsaturated fatty acids. For Great Lakes fish species to function in very cold water, they need these oils to stay fluid under very cold conditions.

It is important to acknowledge the risk of fish consumption due to the presences of some pollutants (also known as persistent organic pollutants or bioaccumulative chemicals) in a fish as it grows and goes up the food chain. This is especially true in predatory fish, even though many persistent organic pollutants have decreased dramatically in the past two decades in the Great Lakes region. Furthermore, because some Great Lakes fish are a good source of omega-3 fatty acids, the benefits of increased consumption should be re-examined in view of the number of local fish consumption advisory limits that were based upon pollutant levels. Fish advisories can be confusing to people that may encourage them to forgo eating fish that could be healthier than many other foods they may choose. Future human health risk assessments of Great Lakes fish consumption should fully consider the health benefits of omega-3 fatty acids along with many other social and economic benefits, especially in traditional subsistence fishing cultures of the upper Great Lakes.

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