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Gas-liquid chromatography analyses have been carried out to investigate the composition of esterified fatty acids in the plasma lipids in 130 Greenland Eskimos, compared with those of 32 Greenland Eskimos living in Denmark and of 31 Caucasian Danes in Denmark. While the Eskimos living in Denmark did not differ substantially from other persons living in Denmark and, from what is found in other studies in Western communities, the Greenland Eskimos showed a completely different pattern. They demonstrated a much higher proportion of palmitic, palmitoleic, and timnodonic acids, while they had a markedly lower concentration of linoleic acid. The total concentration of polyunsaturated fatty acids was lower in Greenland Eskimos than in the other groups. These findings are discussed in the light of the generally accepted opinion of the beneficial effect on plasma lipid levels and on the morbidity of coronary atherosclerosis of a high dietary intake of polyunsaturated fatty acids. As plasma lipid and lipoprotein levels in Greenland Eskimos in a previous study were found markedly lower than those found in Western populations, and as coronary atherosclerosis seems to occur far less commonly among Eskimos in Greenland than among peoples in industrialized countries, it was found difficult to combine these observations with the results from the present study. If dietary differences are the main reason for the differences in plasma lipid concentrations, the results from the present study point more toward qualitative than toward quantitative differences in respect of fatty acid composition of the food.

In the winter of 1976 an examination of the composition of Eskimo food was carried out in north western Greenland. Duplicate specimens of diets collected from 50 adults, equal numbers of males and females, were analyzed for water, ash, protein, fat, individual fatty acids, cholesterol, and carbohydrate. The results are compared with those of typical Danish diets. Seal and the fish are predominant Eskimo food. Marked differences between Eskimo and Danish food were found. The Eskimo diets were richer in polyunsaturated fatty acids, the ratio to saturated fatty acids was 0.84 as compared with 0.24 in Danes. The polyunsaturated fatty acids were predominantly of the linolenic class (n-3) in Eskimos and the linoleic class (n-6) in Danes. Monoenes other than palmitoleic and oleic acids were high in Eskimo diets, but negligible in Danish. The results are related to previous examinations of the plasma lipids in Eskimos. The rarity of ischemic heart disease in Greenland Eskimos may partly be explained by the antithrombotic effect of the long-chained polyunsaturated fatty acids, especially eicosapentaenoic acid prevalent in diets rich in marine oils.

Food specimens have been collected, by means of the double-portion technique, from Greenland Eskimo hunters and their wives, in all seven persons, on seven consecutive days. Their food was found to contain more protein and less carbohydrates than average Danish food and an almost equal amount of fat. Compared with Danish food, the fatty acid pattern of the consumed lipids-essentially of mammalian marine origin--showed a higher content of long chain polyunsaturated fatty acids (especially C20 : 5) and lower contents of linoleic and linolenic acids. However, the sum of the polyunsaturated fatty acids was smaller than in Danish food. Using Keys' formula, describing the serum cholesterol level as a function of the nutritional fatty acids, the essentially lower serum cholesterol level found in Greenland Eskimos was not explained by our findings. It is suggested instead to be a special metabolic effect of the long chain polyunsaturated fatty acids from marine mammals. There might be a similar effect on the plasma triglyceride and very low density lipoprotein concentrations, explaining the much lower plasma concentrations of these components in Eskimos than in Western populations. Our findings might have an essential bearing on the difference in morbidity from coronary atherosclerotic disease between these populations.