BOSTON — The number and kinds of food outlets near schools may be associated with higher rates of obesity among public school students, researchers said here.
Data for nearly 13,000 middle and high school students in 33 public schools in New Jersey showed that nearly 25% of the students were obese compared to the national average of 17%, according toXuyang Tang, MS, from University of Minnesota in Minneapolis and Arizona State University in Tempe, and colleagues.
They found that an added 0.1-mile in the distance between a school and a healthy food outlet increased body mass index (BMI) z score by 0.0111 (P<0.01), and raised the probability for obesity by 0.4% and for overweight or obesity by 0.5%. In addition, a 0.1-mile increase in the distance between a school and the nearest convenience store led to a 0.05 rise in BMI-z score, they reported at the American Public Health Association annual meeting.
However, close proximity (a quarter mile from a school) to healthy food outlets were associated with a reduction in BMI z-score of 0.151 (P<0.01) and reduced probability of obesity. Healthy food outlets were defined as offering five types each of both fresh fruits and vegetables, low-fat dairy, and lean meats, as well as stores that mainly sold fruits and vegetables.
The researchers explained that the study's outcomes suggested a small, but significant, negative relationship between the proximity of healthy food outlets near schools and students' higher weight status.
Statistics from the CDC indicate that obesity has more than doubled in children and tripled in adolescents in the past 30 years.
While recent studies have shown that food environments around schools are associated with obesity rates among students, the research has been flawed, according to Tang's group, as most studies used self-reported height and weight measures.
Tang and colleagues used a random effects model based on student- and school-level data,geocoded food outlets, neighborhood demographics, and crime statistics.
Of 7,170 students from 19 middle schools, 26.46% were obese, as were 22.37% of 5,784 students from 14 high schools. A total of 43.55% of all students from the four N.J. counties (Camden, Newark, New Brunswick, and Trenton) were overweight or obese.
On average, there were 2.75 convenience stores, 3.68 limited‐service restaurants, 0.34 healthy food outlets, and 0.24 supermarkets within a quarter mile of the schools.
The findings add to the existing literature on childhood obesity, suggesting that healthy food outlets around school environments may play a role in stopping or reversing the childhood obesity epidemic, they concluded.
The strengths of this report include a large sample size and multiple credible sources of information, such as neighborhood demographics from U.S. Census Bureau tract-level data and student-level data from the New Jersey Childhood Obesity Study.
Limitations included the use of cross-sectional data so causality could not be shown. Also, schools included in the study were located in poor urban areas so the findings may not be generalizable.
The researchers called for further longitudinal studies to examine a possible causal relationship.