Fish Consumption Advice for Alaskans
While dietary changes are complex in nature, they often coincide with a number of other lifestyle changes that also contribute to increases in chronic diseases such as heart disease, diabetes, and cancer.
Diet and lifestyle factors influence most of the leading causes of death in Alaska. Switching from a subsistence lifestyle and diet to a more sedentary existence and a “Westernized” diet high in saturated and trans fats and carbohydrates has contributed to a pattern of increasing obesity and chronic disease among many indigenous populations in North America and the Pacific Rim.27 The prevalence of obesity in Alaska has increased dramatically in recent years, from 48% in 1991–1993 to 61% in 1999–2001, representing a 26% increase.29 Increasing non-traditional food use and sedentary lifestyles among Alaska Native people have been associated with an increasing chronic disease prevalence, including an increase in hypertension, glucose intolerance, and diabetes. 26-28
Health Benefits of Fish Consumption This section (pages 25–28) is adapted from a previously unpublished review by Tracey V. Lynn, DVM, MPH.
Fish provides a diet rich in high quality protein, low in saturated and trans fats, and rich in omega-3 polyunsaturated fatty acids. Fish contains all of the essential amino acids, and is an excellent source of the fat-soluble vitamins A and D, as well as selenium and iodine. Selenium is an essential trace mineral important for the proper functioning of antioxidant enzymes, the immune system and thyroid gland, and is protective against the toxic effects of mercury. 95
The traditional Alaska Native diet, which is low in saturated fat and high in monounsaturated fat and omega- 3 polyunsaturated fatty acids from fish and marine oils, is considered to be more healthy than the typical Western diet, especially beneficial in preventing heart disease, and possibly beneficial in preventing non- insulin dependent diabetes mellitus.96-99 Fish and marine mammals, and to a lesser extent shellfish, are the only significant direct dietary sources of two types of omega-3 polyunsaturated fatty acids: eicosapentaenoic acid (EPA, 20:5) and docosahexaenoic acid (DHA, 22:6).
In addition to providing healthy fats to the diet, fish is also an excellent source of protein and contains other nutrients in varying quantities depending upon the species. A 3-ounce serving of cooked king salmon provides 40% of the daily requirement of protein, 9% of the daily requirement for iron, and 7% of the daily requirement for vitamin A. 100
Great interest exists in studying the beneficial effects of dietary seafood that is high in omega-3 polyunsaturated fatty acids. This interest traces its origins to two Danish physicians, Bang and Dyerberg, who in 1970 observed a low incidence of cardiovascular diseases in Greenland Eskimos and who showed a strong association between this lack of heart disease and a marine-based diet.101-103 Many subsequent studies have documented additional health benefits from omega-3 polyunsaturated fatty acids. 104-106
A dietary shift from fish, marine mammals, wild game meats and plants to a typical Western diet rich in saturated fat from dairy and meat products and linoleic acid from vegetable oils changes the balance between omega-6 and omega-3 polyunsaturated fatty acids. Specifically, significant dietary increases in omega-6 vegetable oils and decreases in the dietary intake of DHA and EPA (oils from fish and marine mammals) result in an increased ratio of omega-6 to omega-3 polyunsaturated fatty acids in the diet. Diets relying upon fish, wild game and plants provide an estimated 1:1 omega-6 to omega-3 polyunsaturated fatty acid ratio, while the current Western diet provides a ratio that may be as high as 10:1 to 20–25:1.107 A high omega-6 to omega-3 ratio enhances ischemic and inflammatory processes, leading to an increase in chronic diseases. Eicosanoids derived from omega-6 polyunsaturated fatty acids promote inflammation, while those derived from omega-3 polyunsaturated fatty acids are anti-inflammatory, and act as competitive inhibitors of the omega-6 derived inflammatory mediators. 106