Brittany Kaczmarek 1
PH 2755 Nutrition Research Methods
BACKGROUND
According to the National Health Interview Survey, obesity prevalence is highest among
those who have little education and the lowest income (Drewnowski & Specter, 2004).
Individuals of low socioeconomic status (SES) with a limited food budget usually purchase less
expensive, energy-dense foods (Drewnowski et al., 2004). Energy-dense foods provide energy at
low cost but with little nutritional value. An increased risk of obesity develops if these foods are
consumed excessively (Drewnowski et al., 2004). The price of food and income play an
important role in food choices and diet quality. Some low SES individuals consume diets
providing energy through fats, sugars, refined grains and meat products with little intake of
vegetables, fruits and whole grains (Drewnowski et al., 2004). A recent study found those who
came from a socioeconomically disadvantaged background were less likely to purchase groceries
following dietary guideline recommendations (Turrell, Hewitt, Patterson, Oldenburg, & Gould,
2002). Those who had lower income and education levels purchased and consumed fewer fruits
and vegetables (Turrell et al., 2002). This data supports an intervention aimed at improving food
purchasing behavior among this population could be beneficial.
A study conducted by Lang, Mercer, Tran, and Mosca (2000) assessed the awareness and
use of a supermarket shelf labeling program in minority communities. The study found
approximately 29% of customers were aware of the shelf labeling program when they shopped
and minorities were twice as likely to be aware of the shelf labeling program than Caucasians
(Lang, Mercer, Tran, & Mosca, 2000). Minorities were also significantly more likely to use the
program compared to Caucasians (Lang et al., 2000). These findings suggest a shelf labeling
program providing nutrition information at the point of sale level has a positive effect on
individuals who are difficult to attain, especially the minority population. Panichelli, Seman,
Berg and Edwards (2011) evaluated the Shopping Matters program aimed at improving
purchasing behaviors by providing education to low SES individuals on how to purchase
affordable healthy foods. Approximately 60% of participants stated they were either thinking of
or intending on using the skills taught during the grocery store tours (Panichelli, Seman, Berg, &
Edwards, 2011). Seventy-five percent of those who led the tours reported most of the participants
showed competence of the skills they were taught (Panichelli et al., 2011). The grocery store
tours in this study gave the low SES population an opportunity to learn important skills for
Brittany Kaczmarek 2
PH 2755 Nutrition Research Methods
healthy grocery shopping. A randomized control study conducted by Milliron, Woolf, and
Appelhans (2012) combined shelf labeling and grocery store tours to measure purchasing
behavior. The intervention group was provided with a 10-minute nutrition education component,
while the control group only used the shelf labels while shopping. Sixty-nine percent of the
participants in the intervention group reported the program was extremely useful and
approximately twice as many intervention participants noticed the shelf labels compared to the
control group (Milliron, Woolf, & Appelhans, 2012). The intervention group purchased
significantly more amounts of fruits and dark green or bright yellow vegetables than the control
group (Milliron et al., 2012). This study showed combining shelf labeling programs with
nutrition education tours in supermarkets promoted more healthful food purchasing.
Although previous research has shown overall positive effects of both shelf labeling and
grocery store tours on purchasing behaviors, areas of research can still be done. Studies have
evaluated the effects of shelf labeling and grocery store interventions in low-income and
minority groups but have not evaluated these effects on employees who work at supermarkets
and have limited transportation. With half of the employees in this study using public
transportation, access to food is limited. Employees most likely rely on the grocery store in
which they are employed at when shopping for food. Therefore, educating this population on
healthy food options in the store is important for the health of the employees. This intervention
proposes to use nutritional education methods such as shelf labeling and grocery store tours
aimed at grocery store employees of a predominantly minority and low SES community in an
effort to change food purchasing behaviors.
PUBLIC HEALTH SIGNIFICANCE
The prevalence of obese adults in the Houston metropolitan area was 27% in 2012
(United States Department of Health and Human Services Centers for Disease Control and
Prevention [CDC], 2013). Obesity rates are increasing each year in Harris County, and people
are at increased risk for other health conditions such as type II diabetes, hypertension and
dyslipidemia (Nejat, Polotsky, & Pal, 2010). Obesity and its associated complications have been
found to afflict certain populations more often than others. Minority groups in the United States,
with the exception of Asian Americans, have higher rates of obesity and overweight compared to
Brittany Kaczmarek 3
PH 2755 Nutrition Research Methods
American whites (Drewnowski & Specter, 2004). Non-Hispanic Blacks exhibit the highest rates
of obesity at approximately 48%, followed by Hispanics at approximately 43% (Ogden, Carroll,
Kit, & Flegal, 2014). Occurrences of obesity and type II diabetes are found to be higher among
those who are economically disadvantaged (Drewnowski et al., 2004). The study sample will be
a high minority population that lives in a low-income area of Harris County, Texas. Considering
the evidence of high rates of obesity among minority and economically disadvantaged groups,
this study is important because there is an increased risk for obesity and associated complications
among the study’s population. Improving food purchasing behaviors of grocery store employees
living in low SES communities aims to reduce the risk of obesity and the complications related
to the chronic disease.
OBJECTIVE
To compare the effectiveness of shelf labeling and grocery store tours on pre- and postpurchasing behavior of employees who work for a chosen Houston, TX value store over one year
in 2015.
METHODS
Research Design
This project will be a non-controlled trial beginning in spring 2015 to study the
effectiveness of shelf labeling and grocery store tours on improving purchasing behavior of
employees. A shelf labeling program and grocery store tours will be implemented for a year at a
chosen value store of a grocery store chain located in the Houston metro area to encourage
healthier food purchasing habits among employees. At baseline and follow-up, all participants
will complete the National Health and Nutrition Examination Survey (NHANES) Food
Frequency Questionnaire (FFQ) to evaluate their average daily food intake at both time points
(National Cancer Institute [NCI], 2013). Average daily food consumption of each employee at
baseline and follow-up will be compared to demonstrate the efficacy of the project.
Shelf Labeling: Shelf labeling will be implemented using a previously designed program,
known as the M-Fit Supermarket Shelf Labeling Program (Lang Mercer, Tran, & Mosca, 2000).
This shelf labeling program identifies products low in total fat, saturated fat, cholesterol, sodium
Brittany Kaczmarek 4
PH 2755 Nutrition Research Methods
and high in total fiber using a color coded system (Lang et al., 2000). Products will be labeled
green if it is a “Best Choice”, yellow if an “Acceptable Choice”, and red if an “Occasional
Choice”(Lang et al., 2000). Criteria for categorizing products were determined by nutrition
recommendations of the US Dietary Guidelines (Lang et al., 2000).
Grocery Store Tours: Each employee will be allowed paid time to participate in a twenty
minute grocery store tour with the project’s Registered Dietitian. Grocery store tours will be
conducted in groups of no more than five on Tuesdays and Thursdays until every employee has
had an opportunity to participate in a tour. The tours will include nutrition education information
about selecting healthy foods at the grocery store. The tours will educate the employees more
thoroughly on how to use the shelf labeling program and locate labeled products. During the
grocery store tours, employees will be notified they will receive an employee discount of 25%
off items labeled with a green shelf tag.
Study Population
The grocery store population will be made up of approximately 50 employees working
for a value store in a low income community of Houston, TX. The value store to receive the
program will be selected randomly out of the six value stores a part of a grocery store chain. The
age of participants will range from 16 to 70 years, made up of about half males and half females.
The majority of the study population is African American or Mexican American. The mean
educational level of the participants is 12th grade and about half of the employees take public
transportation to work. The only inclusion criterion for this study is the individual has to be an
employee at the value store in which the project is implemented. All participants will provide
written informed consent before partaking in the study. IRB approval will be acquired from the
University of Texas Health Science Center at Houston.
Collection of Variables
The exposure of this study is the shelf labeling program and the grocery store tours
providing nutrition education. The outcome measured will be healthier food purchasing
behaviors. The NHANES FFQ addresses items including how often participants consume a
certain food or beverage, the types of cooking techniques utilized, and any additional ingredients
Brittany Kaczmarek 5
PH 2755 Nutrition Research Methods
used while cooking (NCI, 2013). The FFQ is available in English or Spanish and does not
include portion sizes. This qualitative FFQ is less burdensome than other FFQs (NCI, 2013).
Each employee will complete a self-administered NHANES FFQ at baseline and the one year
follow-up to evaluate any changes in average daily intake of foods across the year.
Statistical Analysis
Differences in pre- and post-purchasing behavior will be evaluated to assess effectiveness
of the shelf labeling and grocery store tour program. The six food groups evaluated will be dairy,
fruits, vegetables, protein foods, grains and oils. Food group data will be represented using mean,
median and standard deviation of intake at both baseline and the one year follow-up. Table 1 will
display the differences in food group intake between baseline and follow-up using data obtained
from the NHANES FFQ. Food group intake will be used to evaluate pre- and post- purchasing
behaviors of the employees. The difference in mean estimations of baseline and follow-up data
will be assessed using a paired t-test to determine statistical significance. Analyses will be
conducted using STATA version 13. Statistical significance will be achieved at p < 0.05. Graph
1 exhibits the expected percentage change of food group consumption in the employees by
gender.
Limitations
This study is the first to evaluate how shelf labeling and grocery store tours can benefit
food purchasing behaviors among employees of a value store in a low-income community;
however, there are limitations to this study to be considered. First, there is potential for recall
bias. Participants’ under- and over-reporting food consumption is common using self-reported
measures such as FFQs. This limits the accuracy of the data. Another limitation of this study is
the relatively small sample size. The study will be implemented at only one value store with 50
employees. Due to the limited sample size, the power and generalizability of the study is
reduced. Future research on this topic should acquire a larger sample size to measure the data.
Increasing the power and generalizability of the study while also decreasing bias should improve
the validity of the results.
Brittany Kaczmarek 6
PH 2755 Nutrition Research Methods
References
Drewnowski, A., & Specter, S. E. (2004). Poverty and obesity: The role of energy density and
energy costs. The American Journal of Clinical Nutrition, 79(1), 6.
Lang, J. E., Mercer, N., Tran, D., & Mosca, L. (2000). Use of a supermarket shelf-labeling
program to educate a predominately minority community about foods that promote heart
health. Journal of the American Dietetic Association, 100(7), 804-809.
doi:http://dx.doi.org.www5.sph.uth.tmc.edu:2048/10.1016/S0002-8223(00)00234-0
Milliron, B., Woolf, K., & Appelhans, B. M. (2012). A point-of-purchase intervention featuring
in-person supermarket education affects healthful food purchases. Journal of Nutrition
Education and Behavior, 44(3), 225-232.
doi:http://dx.doi.org.www5.sph.uth.tmc.edu:2048/10.1016/j.jneb.2011.05.016
National Cancer Institute. (2013). Usual dietary intakes: NHANES food frequency questionnaire
(FFQ). Retrieved from http://appliedresearch.cancer.gov/diet/usualintakes/ffq.html
Nejat, E. J., Polotsky, A. J., & Pal, L. (2010). Predictors of chronic disease at midlife and beyond
- the health risks of obesity. Maturitas, 65(2), 106-111.
doi:http://dx.doi.org.www5.sph.uth.tmc.edu:2048/10.1016/j.maturitas.2009.09.006
Ogden, C. L., Carroll, M. D., Kit, B. K., & Flegal, K. M. (2014). Prevalence of childhood and
adult obesity in the united states, 2011-2012. United States: American Medical Association.
Panichelli, J., Seman, L., Berg, C., & Edwards, L. (2011). Skills-based nutrition education for
low-income families at the supermarket. Journal of the American Dietetic
Brittany Kaczmarek 7
PH 2755 Nutrition Research Methods
Association, 111(9, Supplement), A48.
doi:http://dx.doi.org.www5.sph.uth.tmc.edu:2048/10.1016/j.jada.2011.06.171
Turrell, G., Hewitt, B., Patterson, C., Oldenburg, B., & Gould, T. (2002). Socioeconomic
differences in food purchasing behaviour and suggested implications for diet-related health
promotion. Journal of Human Nutrition and Dietetics : The Official Journal of the British
Dietetic Association, 15(5), 355-364. doi:10.1046/j.1365-277X.2002.00384.x
United States Department of Agriculture. (2011). Food Groups. Retrieved
http://www.choosemyplate.gov/food-groups/
United States Department of Health and Human Services Centers for Disease Control and
Prevention. (2013). Overweight and obesity (BMI): Houston-Sugarland-Baytown, TX
metropolitan statistical area 2012. Retrieved from http://apps.nccd.cdc.gov/BRFSSSMART/MMSARiskChart.asp?yr=2012&MMSA=37&cat=OB&qkey=8261&grp=0
Brittany Kaczmarek 8
PH 2755 Nutrition Research Methods
Table 1. Food Group Intake Measured at Baseline and One Year Follow-Up Using NHANES
FFQ
Food
Groups
Daily
Recommended
Number of
Servings*
Daily
Intake
at
Baseline
Mean
Dairy
Fruits
Vegetables
Protein
Foods
Grains
Oils
SD
Daily
Intake
at
FollowUp
Median Mean
SD
Median
PValue
3 cups
1 ½ -2 cups
2-3 cups
5-6 ½ ounces
5-8 ounces
5-7 teaspoons
SD = Standard Deviation
*According to the United States Department of Agriculture (2011); Servings recommended will vary depending on age, gender
and amount of physical activity.
** p ≤ 0.05
Graph 1. Gender Comparison of Pre- and Post- Daily Intake Percentage Difference
Oils
Grains
Protein Foods
% Change Female
Vegetables
% Change Male
Fruits
Dairy
-4%
-2%
0%
2%
4%