Dietary fat associated with insulin concentrations in Native American adolescents

Abstract

The prevalence of type 2 diabetes among Native American populations is escalating, particularly in children and adolescents. Dietary factors appear to influence the development of diabetes, and therefore, are modifiable risk factors for primary prevention. Studies evaluating the dietary habits of Native American adolescents are sparse. Furthermore, studies examining the relationship between insulin and dietary factors have been limited to adult populations. The objective of this study was to describe dietary intake and food consumption patterns and examine dietary factors associated with fasting and 30-minute postprandial insulin levels among adolescents from the Zuni Pueblo, New Mexico. Dietary intake and plasma insulin concentration data were collected from Zuni male and female adolescents, 15--20 years of age, participating in the Zuni Diabetes Prevention Project (ZDPP). The ZDPP, a 4-year, cross-sectional, school-based intervention study was designed to reduced risk factors of type 2 diabetes among Zuni adolescents. Using 24-hr dietary recalls to estimate dietary intake, dietary data was collected during 1993-1994 (baseline) and spring of 1997 (3 years of intervention exposure). Modified glucose tolerance tests were conducted to measure plasma insulin concentrations. Baseline dietary data was adjusted to remove day-to-day variation and compared to national dietary guidelines. Logistic regression was conducted to examine associations between nutrient intake and insulin concentrations. Estimated daily fat intakes of Zuni adolescents exceeded recommendations, whereas, dietary fiber intakes did not achieve guidelines. Less than half of Zuni females met or exceeded dietary recommendations for most micronutrients. Less than 50% of Zuni males consumed recommended levels of vitamin A, folate, vitamin E, calcium, and magnesium. Zuni adolescents reported a diet low in nutrient-dense vegetables, high-fiber grains, and fruits. Sugared-beverages were a significant source of energy and total carbohydrate. Among Zuni males, dietary fat and protein intakes were significantly inversely associated with insulin levels. A negative association between dietary fat and insulin levels was not evident among females. Positive associations were observed for total carbohydrate intake in the unadjusted models. Our results suggest that diets higher in fat or protein compared to high-glycemic carbohydrates may be less deleterious in individuals with minimal hyperinsulinemia.