Serum Cholesterol Levels in American Indians

Abstract

AN OPPORTUNITY to examine the level of total serum cholesterol of Indians residing on five reservations in the United States was afforded when the Public Health Service, in cooperation with the U.S. Department of Interior, conducted the Indian Health Survey from October 1955 through June 1956. Such an examination is of epidemiological initerest, since an early study reported infrequent coronary heart disease among the Navajos which prompted an examination by subsequent investigators (1, 2). They found in a small sample of hospitalized Navajos a low serum cholesterol level when compared with that of a clinic group from the Cleveland population, although the Navajo dietary fat intake apparently was not much less than that of the general diet. These findings are contrary to still inconclusive evidence that a high fat intake is reflected in a high concentration of serum cholesterol in the blood and, perhaps, in an increased tendency to develop atherosclerosis (3, 4). It was theorized from these findings that genetic factors, rather than dietary factors, were the principal cause of the low serum cholesterol level and low coronary heart disease occurrence among the Navajos. Other investigators, in studying different groups of the Navajo population, were not impressed that the Navajo mean serum cholesterol level was particularly low. The,y concluded that the mean level which they observed does not support the hypothesis that the low prevalence of coronary heart disease among the Navajos is a result of low blood lipids (5). It is of particular interest, therefore, to examine the serum cholesterol levels of the American Indians in this survey and to compare these with levels of an American white population having a high mean serum cholesterol level (2). The American Indians who were examined resided on the following reservations: Acoma, N. Mex.; Crow, Mont.; Lac Courte Oreilles, Wis.; San Carlos, Ariz.; and Yankton, S. Dak. The relationship with age was also examined and is presented as additional statistical evidence concerning the level of serum cholesterol of populations (6).