摘要：Objectives. We tested hypotheses about the relationship between neighborhood-level food sources and obesity, controlling for individual-level characteristics. Methods. Data (collected November 2006–April 2008) derived from a random-digit-dial sample of 5688 community-dwelling adults aged 50 to 74 years residing in 1644 census tracts in New Jersey. Using multilevel structural equation models, we created latent constructs representing density of fast-food establishments and storefronts (convenience stores, bars and pubs, grocery stores) and an observed indicator for supermarkets at the neighborhood level, simultaneously modeling obesity and demographic characteristics (age, gender, race, education, household income) at the individual level. Results. When we controlled for individual-level age, gender, race, education, and household income, densities of fast-food establishments and storefronts were positively associated with obesity. Supermarkets were not associated with obesity. Conclusions. Because people living in neighborhoods with a higher density of fast food and storefronts are more likely to be obese, these neighborhoods may be optimal sites for interventions. Rates of obesity increased more than 100% between the 1970s and 2008. 1 Although rates have leveled off since 2003and 2004, 2 today more than a third of the US population is obese, and estimates indicate that by 2030 between 42% and 51% of the population will be obese. 3 People aged 45 to 64 years are more likely to be obese than are those in any other age group. 4 If obesity trends continue at their current rate, disability rates among persons aged 50 to 69 years are projected to increase by 1% per year through 2020. 5 Because of the relationships between obesity, poor health, and high medical expenditures, obesity is a greater threat to public health than either smoking or drinking. 6 Trends in obesity rates are most likely the result of changing environmental factors, including agriculture, food processing and marketing, transportation, and physical demands of work. Because the characteristics of the neighborhoods in which people live can make it easier for them to consume excessive calories and more difficult to expend those calories, 7 it is likely that there is an association between obesity and the neighborhoods in which people live. Yet since most existing studies of the relationship between neighborhoods and obesity among older adults focus on the socioeconomic characteristics of neighborhoods 8–14 rather than the neighborhood food environment, we lack understanding of how specific characteristics of the neighborhood food environment influence obesity. The analyses that follow examine the extent to which the local food environment is related to obesity among older adults, controlling for individual characteristics with known associations to obesity, including age, gender, socioeconomic status, and race. Evidence regarding the extent to which the neighborhood food environment is associated with obesity in the adult population is conflicting, with some studies showing a positive association 15–19 and others finding that proximity to fast-food restaurants is not associated with body mass index (BMI). 20–23 Similarly, although some studies found that proximity to supermarkets decreased the risk of obesity, 18,19,21,24 others found that supermarkets were not associated with BMI. 22,23 Although few studies have examined the effects of neighborhood environment and obesity on older people, Yen et al. 25 suggest that obesity among older adults may be even more strongly influenced by neighborhood characteristics than is the case for school-aged children and younger adults. Like studies of adults in general, studies linking characteristics of neighborhood food environments and obesity in older people yield conflicting findings. Hanibuchi et al. 26 found that better access to supermarkets, fast-food outlets, and convenience stores was positively associated with obesity among older people in Japan, whereas Morland et al. 27 found that the presence of supermarkets was associated with a lower prevalence of obesity and that the presence of convenience stores was associated with a higher prevalence of obesity in a large community-dwelling sample of Americans. Rundle et al. 24 suggest that because density measures for food sources such as supermarkets, convenience stores, and fast-food restaurants are correlated with each other, their associations with obesity may be difficult to disentangle. Moreover, because not all studies examine these neighborhood food sources in tandem with one another, findings across studies are difficult to compare. Further adding to the complexity of this issue, most studies do not simultaneously adjust for the inherent nesting of people in neighborhoods and measurement error. We investigated the relationship between obesity and the local food environment among older adults. We tested the following hypotheses depicted in Figure 1 : (1) when age, gender, income, education, and race are controlled for, people living in neighborhoods with more fast-food restaurants and storefronts (small grocery stores, convenience stores, and bars) are more likely to be obese than people living in neighborhoods with fewer of these amenities; and (2) when these same individual-level variables are controlled for, people living in neighborhoods with greater availability of supermarkets will have lower rates of obesity than those living in neighborhoods where supermarkets are less prevalent. Open in a separate window FIGURE 1— Multilevel structural equation models of individual-level obesity with (a) characteristics at the individual (within) level and (b) food sources at the neighborhood (between) level: Ongoing Research on Aging in New Jersey: Bettering Opportunities for Wellness in Life (ORANJ BOWL), 2006–2008. Note. NS = not significant. The 2 arrows pointing to Obesity are indicators for the measurement error associated with the observed variable.
