Coronary Heart Disease Among the Navajo Indians

Abstract

A 6-year cohort and descriptive epidemiologic study in the Many Farms Navajo Indian population has revealed only 4 cases of coronary heart disease in 508 adults 30 years old or older. The incidence is significantly low when an appropriate age and sex matched segment is compared to the Framingham population, whose people have undergone intensive study for coronary heart disease. Analysis of so-called "risk" variables in a comparison with the Framingham population reveals that blood pressure levels are significantly lower throughout the entire studied age range in both male and female subjects. Electrocardiographic evidence of left ventricular hypertrophy is also significantly low. Cholesterol levels appear to be somewhat, lower, although direct comparison cannot validly be made. Host and environmental variables of possible relevance in causation of coronary heart disease are described in the Navajo setting. Of all factors, diet has been studied most intensively, demonstrating that Navajo have a high animal fat intake of adequate caloric value. It is suggested that multiple factors in addition to diet are operative through mechanisms that are in part expressed by the so-called "risk" variables (blood pressure levels, left ventricular hypertrophy, and cholesterol levels) in determining the low incidence of coronary heart disease among the Navajo.