Understanding and Preventing Breast Cancer Disparities in Latinas

Metabolic Response to Western vs. Indigenous Diets in Hispanic Women [COMIDAS]

Project Leader:

Marian Neuhouser, PhD, Associate Member, Public Health Sciences, FHCRC

Health disparities are an important public health problem and reduction of these disparities is a Healthy People 2010 goal.1-4 Particularly concerning is that health disparities are more common among racial and ethnic minorities compared to non-Hispanic whites in the United States.3, 5 Because these groups already have many societal disadvantages in employment, income and education, reducing health disparities should take a high priority to prevent further widening of social, cultural and resource gaps. This proposal focuses on understanding the relationship between dietary patterns that increase risk of obesity in Hispanic women. This is an important issue in the arena of health disparities because nearly 80% of Hispanic women in the U.S. are overweight or obese.6 Obesity increases the risk of numerous chronic diseases including diabetes, gall bladder disorders, cardiovascular disease and several common cancers.7-9 These obesity-related health consequences are likely the result of complex interactions of genetic characteristics and environmental exposures, including diet. Comprehensive approaches are needed to better understand these interactions and their influence on health disparities. Other projects in this application focus on breast cancer risk factors, etiology and barriers to screening among Hispanic women. In the project proposed here, we will complement the overall application by understanding how diets that are commonly consumed by Hispanic women and their families lead to disordered metabolism and increased risk of obesity, which in turn may increase risk of breast cancer. Effective interventions for obesity and cancer prevention can best be designed and implemented when the biology of food patterns and obesity is better understood. The focus of this project fits well into our P50 theme, which is to understand breast cancer precursors and to reduce breast cancer morbidity and mortality among Latinas.

Mexicans are the largest immigrant group in the United States with an estimated 10 million Mexican-American women currently in the U.S. As they acculturate to this country, Mexican immigrants change their dietary habits from traditional (indigenous) foods with plentiful fruit, vegetables and complex carbohydrates rich in fiber and other compounds to a Western-style diet high in fat and refined carbohydrate, but low in plant foods.10 Particularly concerning is that the food choices made by Mexican immigrants, many of whom are of lower socio-economic status, are driven partly by their inability to procure and purchase healthy foods.11 The disparity in both food availability and purchasing power fuels a tendency to obtain and consume a low-cost, Western style diet.12-14 When this diet is superimposed on persons with a “thrifty genotype” who are evolutionarily adapted to diets high in legumes and complex carbohydrates, it may lead to an abnormal metabolic response that favors adipose deposition and numerous health risks. Thus, ancestral genetic characteristics likely have an important role in metabolic response to specific dietary patterns and subsequent health risks. This phenomenon may partly explain the tendency for Mexicans and other immigrants from the Americas to become obese after just one generation in the United States.15-20

The overall goal of this project is to test the metabolic response to Western and traditional Mexican diets in Hispanic women. We will also investigate whether ancestral genetic variation mediates the response to each diet. We hypothesize that the biological response to a Western dietary pattern produces detrimental metabolic profiles favoring adipose deposition and inflammation, which leads to increased risk of adverse health events, including increased risk of breast cancer. Conversely, we hypothesize that the physiologic response to an traditional Mexican diet will produce a favorable metabolic profile. We further hypothesize that genetic ancestry mediates this biological response to a Western dietary pattern. We propose to test our hypotheses using the following specific aims:

Primary Aims

  • To test in a randomized cross-over experimental feeding study the metabolic response to an traditional Mexican diet vs. a Western diet in 50 first and second-generation Hispanic women living in the greater Seattle area. The metabolic response will be measured by blood concentrations of the following biomarkers assessed before and after each feeding period: insulin, glucose, insulin-like growth factor 1 (IGF1), insulin like-growth factor binding protein 3 (IGFBP3), leptin, adiponectin, interleukin-6 (IL-6), C-reactive protein (CRP) and serum amyloid-A (SAA).
  • To investigate whether genetic characteristics, as assessed with Ancestry Informative Markers, mediate the metabolic response to each tested diet.

Secondary Aims

  • To compare the experimental traditional Mexican and Western diets with respect to measures of hunger and satiety.
  • To test whether Ancestry Informative Markers explain variance in adiposity measures in study participants.

To meet these aims, we will conduct a study in which participants will be randomized to receive either an isocaloric Indigenous traditional Mexican diet or a Western diet for 24 days. All foods and beverages will be prepared by the Human Nutrition Laboratory (HNL) at the Fred Hutchinson Cancer Research Center (FHCRC). After a 4-week wash-out period, participants will cross over to the other arm and be given the alternate diet for 24 days. Blood and urine specimens will be collected before and after each feeding period to test baseline and post-intervention metabolic response as defined by various inflammatory and cancer susceptibility biomarkers including insulin-like growth factor 1 (IGF1), insulin-like growth factor binding protein 3 (IGFBP3), leptin, adiponectin, interleukin-6 (IL-6), C-reactive protein (CRP) and SAA (serum amyloid-A). DNA extracted from whole blood will be used to test whether a panel of 128 Ancestry Informative Markers (AIMs) is associated with metabolic response to the diets and other phenotypic traits of obesity, which relate to breast cancer risk.

The objective of the PUEDO initiative is to understand the antecedents of breast cancer in the Latina population by conducting a comprehensive investigation of breast cancer biology, etiology and prevention in Hispanic females. The COMIDAS study contributes to the overall Center objectives (particularly related to antecedents of breast cancer) by rigorously testing in a randomized, cross-over feeding study whether differential metabolic response exists in relation to traditional, Indigenous diets vs. Western diets in Hispanic women. This study addresses an important problem with respect health disparities in Hispanic women who are at greater risk of obesity compared to non-Hispanic whites.6 While the etiology of obesity is complex and multi-faceted, Hispanic women may be at particular risk due to genetic characteristics that favor the thrifty genotype and adipose deposition when consuming a low-plant food, highly-refined carbohydrate diet (i.e. Western diet). Thus, this project addresses both individual level (genotype) and social context (food availability and affordability) factors related to health disparities.


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