COMIDAS Comparing Original Mexican Diets and Standard US Diets

Chronic disease risk, including breast cancer risk, is not uniform across race and ethnic
groups in the United States. This variation in disease risk may be due to environmental
exposures (including diet), genetic susceptibility, disparities in access to health
screening, diagnosis and medical care, or combination of these factors. Here we have shown
that Hispanic women in the U.S. are more likely to be overweight or obese compared to
non-Hispanic whites. Some of the excess obesity risk is likely due to the lack of
neighborhood availability and affordability of fruit, vegetables, lean protein and whole
grains. Whether an inexpensive and widely available highly processed/refined, nutrient poor
diet superimposed on a genetic background favoring adipose deposition (i.e., the "thrifty
genotype") is metabolically detrimental has not been investigated. Research to test the
metabolic response to Indigenous and Western diets in Hispanic women may provide important
information about the etiology of obesity and obesity-related diseases in Hispanic women,
including risk of breast cancer. Since reducing disparities in obesity-related diseases,
including breast cancer, is an important public health goal, identifying potential programs
for prevention should receive high priority.

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.
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. The disparity in both food availability and purchasing power fuels a
tendency to obtain and consume a low-cost, Western style diet. 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.

Inclusion Criteria:

- Healthy Women of Mexican Descent

- Age between 18-45 years

Exclusion Criteria:

1. current physician-diagnosed diseases that require dietary restrictions or certain
medications, including but not limited to, diabetes mellitus, kidney disease, other
metabolic disorders, and cardiovascular disease requiring diet modifications

2. impaired glucose tolerance defined as fasting glucose > 100 mg/dL; all participants
will complete a fasting blood glucose determination

3. BMI < 18.5 kg/m2 or > 40.0 kg/m2

4. current pregnancy or pregnancy in last year, lactation or plans to become pregnant
during the study period

5. cessation of menses (either natural or surgical)

6. any previous cancer diagnosis or treatment within the previous five years (excluding
non-melanomatous skin cancer)

7. restrained eating habits

8. current use of tobacco (any smoking) or alcohol (> 2 drinks/day)

9. inability (e.g., food allergy/intolerances) or unwillingness to consume the study
foods.