Genetic ancestry in relation to the metabolic response to a U.S. versus traditional Mexican diet: a randomized crossover feeding trial among women of Mexican descent

BACKGROUND: Certain populations with a large proportion of Indigenous American (IA) genetic ancestry may be evolutionarily adapted to traditional diets high in legumes and complex carbohydrates, and may have a detrimental metabolic response to U.S. diets high in refined carbohydrates and added sugars. We tested whether IA ancestry modified the metabolic response to a U.S. versus traditional Mexican diet in a controlled dietary intervention. METHODS: First and second generation Mexican immigrant women (n=53) completed a randomized crossover feeding trial testing the effects of a U.S. versus traditional Mexican diet. The metabolic response to the diets was measured by fasting serum concentrations of glucose, insulin, IGF-1, IGFBP-3, adiponectin, CRP, IL-6, and computed HOMA(IR). Blood collected at baseline was used for genotyping and estimation of African, European, and IA ancestries with the use of 214 Ancestry Informative Markers. RESULTS: The genetic ancestral background was 56% IA, 38% European, and 6% African. Women in the highest IA ancestry tertile (>62%) were shorter in height, less educated and less acculturated to the U.S. lifestyle, and tended to have higher waist-to-hip ratio compared to women in the middle and lowest IA ancestry tertiles, respectively. Compared to the U.S. diet, the traditional Mexican diet tended to reduce glucose, insulin, IGF-1, IGFBP-3, and HOMA(IR) among women in the middle IA ancestry group (IA ancestry ≤45–62%); while having no effect on biomarkers related to inflammation. CONCLUSIONS: We observed modest interactions between IA ancestry and the metabolic response to a U.S. versus traditional Mexican diet among Mexican immigrant women.