2008 Tinker Summer Research Report

Jessica Joseph
School of Public Health

"Micronutrient Supplementation, Child Feeding Practices, Child Growth and Development and Weight Change in Women: a Multi-Study Follow-up of a Cohort in Mexico"

Hungry? Here’s what you will find to eat at any corner store.

The research project I am working on is comprised of three sub-studies that will examine:

My work focuses on the first and second objectives.

BACKGROUND
Undeniably, obesity is a growing issue in many developing Latin American countries, including Mexico. A risk shift has been seen, where overweight individuals are now poor, instead of rich. An increase in obesigenic food available at lower prices combined with fewer healthier food choices and a lack of nutrition education has contributed to the rise of obesity among those living in poverty.

Obesity increases the risk of chronic diseases such as diabetes, hypertension, heart disease, stroke, and a number of cancers, meriting concern by public health professionals. One risk factor for childhood obesity is low birth weight (LBW). Although advantageous for infants experiencing undernutrition, studies are now showing it is detrimental in environments where overnutrition is a concern. The determinants of weight change for adults are extremely complex to ascertain as individual, environmental, and societal influences all contribute to overweight and obesity.

In the last six years the obesity rate of the sample population doubled. Difficulties in determining the cause of obesity is due to the plethora of potential factors, including but not limited too foods high in calories but low in nutrients, larger portion sizes, increases in snacking and/or eating outside the home, and decreases in physical activity. In order to design an intervention that addresses rising obesity rates, one must first discover what the contributing causes are.

METHODS
Since 1997, a cohort of 256 women and their children, living in a semi-rural community in Morelos State, Mexico, have been followed. Baseline data collection took place from 1997 to 2000; a follow-up study was conducted from April to August 2005, and in July of 2008 a second follow-up study began. Table 1 describes the measurements and questionnaires that are being applied. All questionnaires that were applied in the original study were used again in order to allow comparisons to be made to the baseline data. However, appendages were made to the both the Food Frequency (FFQ) and Physical Activity (PAQ) questionnaires to collect more specific data in regards to the determinants of obesity. Both the FFQ and PAQ revisions were based on input and conversations with INSP employees who are experts in the respected fields.

Table 1           Summary of information being collected

Moto-taxi: Cheap and convenient, how are they impacting physical activity?

In the FFQ to the mother, the categories for beverages, fast food/prepared foods, and added sugars were extended. Mothers will also be asked four supplemental questions regarding whether or not there have been any changes in their dietary behavior in the past one or ten years. The FFQ for the child is applied to the mother, as it was in the baseline data collection. However, because the children are now 9-10 years of age, the decision was made to apply a supplemental questionnaire directly to the child—twelve questions that ask them what they eat and drink when they are going to school, at school, and returning home from school.

The PAQs required considerable more work to revise. First, I conducted an extensive literature review on pre-existing survey instruments. Next, I interviewed two INSP researchers who conduct studies in Mexico that measure physical activity. From these conversations, I was able to compare and contrast several versions of PAQs. The final version we decided on was a combination of the International Physical Activity Questionnaire (IPAQ) and the 2005 Mexican National Health and Nutrition Survey (ENSANUT). Thirteen questions are asked to the mothers that assess not only vigorous, moderate, and sedentary behavior, but also time spent sitting and time spent in transport.
The PAQ for children is applied to the mother, just as the primary FFQ is. There are eighteen questions that ask about physical activity, television, video games, homework, time spent in a car, and sleep. All questions are asked twice—to determine the number of hours spent of the activity on weekdays and weekends, respectively.

Anthropometric measures are also being taken (weight, height, and waist circumference). Hip circumference was eliminated, based on a published paper where the authors found that waist circumference and body mass index were better predictors for the risk of chronic disease than waist-to-hip ratio. Skinfolds will not be taken due to budgetary constraints.

RESULTS
This project is ongoing. Data has been collected on over 50% of the participants and hopes to be complete by the end of the fall, 2008. Data is doubly-entered by an INSP employee before being sent to the US where the results can begin to be analyzed. In 2005, LBW and rapid growth in the first year of life were found to be risk factors for obesity at age five. Therefore, one hypothesis I will be examining is if LBW will still be a risk factor for obesity at age eight (using age and sex-specific BMI). Another suspected hypothesis is that women’s physical activity has decreased due to the abundance of a new mode of transportation in the form of moto-taxis (rickshaws pulled behind motorcycles). Where women once walked to their neighbors, the market, or with their children to school, moto-taxis now offer an abundant, inexpensive, and convenient mode of transportation through their community. This decrease in physical activity is possibly a major determinant in the significant increase of obesity rates.

Team of field workers

CONCLUSION
INSP has maintained relationships with the community members of the town where the study was conducted throughout the last 10 years. From their long-standing presence in the community they have been able to observe many changes that affected how this second follow-up study should be conducted. Observational data has allowed insight into the types of measures that need to be collected. For example, chips, candy, and soda are readily available at any corner stores, so it is suspected that the food environment has changed in numerous ways. This has spurred questions regarding changes in eating patterns. Finding out how and why diets have changed will be crucial to identifying the determinants of obesity.

1. Whitney E, Rolfes SR. Understanding Nutrition, Eleventh Edition. USA: Thomson Wadsworth; 2008.

2. Neufeld LM, Hernandez-Cordero S, Fernald LC, Ramakrishnan U. Overweight and obesity doubled over a 6-year period in young women living in poverty in mexico. Obesity (Silver Spring). 2008;16:714-717.

3. Neufeld LM, Jones-Smith JC, Garcia R, Fernald LC. Anthropometric predictors for the risk of chronic disease in non-diabetic, non-hypertensive young mexican women. Public Health Nutr. 2007:1-9.

4. Jones-Smith JC, Fernald LC, Neufeld LM. Birth size and accelerated growth during infancy are associated with increased odds of childhood overweight in mexican children. J Am Diet Assoc. 2007;107:2061-2069.