Native inhabitants of northern parts of Canada, Alaska and Greenland rely on marine sources for their protein and energy needs. These food sources tend to include both marine mammals and cold water fish that contain high levels of long-chain polyunsaturated fatty acids in their tissues. In particular, the concentrations of omega-3 (n-3) fatty acids in these foods are higher than those found in typical high energy and protein foods in the Western diet. Epidemiology suggested that high intakes of two such n-3 fatty acids, eicosapentanoic acid (EPA, C20:5 (n-3)) and docosahexanoic acid (DHA, C22:6 (n-3)), was associated with a decreased risk of coronary heart disease and thrombosis amongst native populations eating traditional diets. Subsequently, a large body of clinical research has shown that increasing the intake of EPA and DHA can produce similar effects for those consuming the typical Western diet.
Researchers1 have compared the fatty acid concentrations of 80 Alaskan Yupik Eskimos living in a village on the Kuskokwim River (population 620 people) or a coastal village on the Bering sea (population of 370 people) with non-native control populations from Oregon, using data collected in 1984. Coastal Eskimos had access to Western foods in their stores, but the high prices meant than in general they were not consumed as part of their regular diet. Coastal Eskimos ate seal oil, marine birds, fish and mammals more frequently than the river residents, who instead consumed salmon more frequently. Concentrations of EPA, DHA and total plasma n-3 fatty acids were 13, 6.8 and 4.3 times higher, respectively, in the Eskimo populations compared to the non-native controls group. Concentrations on the n-3 fatty acids were higher in coastal Eskimos that the river dwelling counterparts.
The concentrations of the n-3 fatty acids in plasma reflected the intake of fatty marine fish and marine mammals consumed in the diets. Because the Eskimo populations had very low intakes of meats from terrestrial origin, they had very low intakes of arachidonic acid (AA, C20:4 (n-6)). The ratios of EPA to AA was 1.16 and 0.70 for coastal and river Eskimos, respectively. These ratios were 14 and 9 times the ratios in the non-native control population. Intakes of both linoleic acid (LA, C18:2 (n-6)) and dihomo-γ-linolenic acid (DGLA, C20:3 (n-6)) were higher in the river population compared to the coastal populations and this was reflected in higher plasma levels of these fatty acids. Total n-3, EPA, DHA and AA concentrations in plasma increased with age amongst the Eskimo populations, whereas plasma concentrations of stearic acid (SA, C18:0), DGLA, LA and plamitic acid (PA, C16:0) decreased with age.
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