Metabolic Studies of Eskimos in the Canadian Eastern Arctic

Abstract

The average concentrations of non-protein nitrogenous constitutents of the bloods of forty-six Eskimos were found to be higher than of peoples elsewhere and could not be explained by impairment of kidney function nor by conditions generally known to lead to such high values otherwise. Retention of nitrogen in the blood appears to be a physiological phenomenon among these Eskimos and is apparently due to the high protein diets. The concentrations of chlorides in plasma were determined in thirty-four Eskimos and both maximum and average values were higher than the average renal threshold level of NaCl of peoples elsewhere. In spite of these high values, the concentrations of chlorides found in the urines were extremely low. The possible significance of these findings is briefly discussed. None of the urines collected under ordinary conditions contained glucose or acetone according to the usual tests. The absence of glucose fits in with the absence of diabetes clinically (Rabinowitch, '36) and to explain the absence of ketonuria it does not appear necessary to seek for some unknown mechanism for utilization of fat. When food is plentiful, fat is not regarded as a relish and the carbohydrate contents of certain foods, the high protein intake and the potential sugar production from protein are such that the ratio of fatty acid to glucose is below the generally accepted level of ketogenesis. Though there was no glycosuria and no clinical evidence of diabetes mellitus, the average blood sugar of thirteen Eskimos in the fasting state suggests some difficulty in the utilization of carbohydrates. The blood sugar time curves obtained in these individuals following ingestion of glucose clearly indicated that these Eskimos were unable to utilize large quantities of glucose in pure form. Respiratory quotients lower than 0.7 were found in five of ten individuals in the fasting state and in three of eight tests in two individuals after administration of fat meals and, though conditions were not ideal for this type of work, no sources of error could be detected. The combined data, therefore, suggest that, though there is nothing peculiar about the absence of ketosis, it is still possible that the metabolism of fat in these Eskimos may to some extent be different from peoples elsewhere and that in these Eskimos may be found the solution to the controversy with respect to the conversion of fat to sugar. The basal metabolic rates of these Eskimos appear to be high. The data fit in with the cold environment which is known to increase metabolism and also with the food habits of these people, in view of the high specific dynamic action of protein. Urines were examined spectrographically with respect to a number of inorganic elements. No lead was found in any of the twenty-four specimens examined though the sensitivity of the method employed is approximately 5 × 10^-8 gm. per cubic centimeter. The significance of these findings with respect to arteriosclerosis is briefly discussed. The copper contents of the urines, as determined spectrographically, were essentially the same as found by chemical analysis. According to the spectrograms, the urines contained relatively large quantities of magnesium. The explanation is not clear, but the large amounts of seal meat in the diets and the known purgative action of this meat are suggestive. The absence or at least rarity of rickets among these Eskimos, in spite of their proximity to the Pole and pigmentations of the skin, appears to be due to the long periods during which infants are breast fed and the fact that the vitamin D-content of seal oil is equal to that of the best cod liver oil.