based on data from a new cross-sectional study of more than 3,000 communities.
Although increased healthy eating has been associated with reduced risk of obesity and with reduced cancer incidence and mortality, access to healthier eating remains a challenge in communities with less access to grocery stores and healthy food options (food deserts) and/or easy access to convenience stores and fast food (food swamps), Malcolm Seth Bevel, PhD, of the Medical College of Georgia, Augusta, and colleagues, wrote in their paper, published in JAMA Oncology.
In addition, data on the association between food deserts and swamps and obesity-related cancer mortality are limited, they said.
“We felt that the study was important given the fact that obesity is an epidemic in the United States, and multiple factors contribute to obesity, especially adverse food environments,” Dr. Bevel said in an interview. “Also, I lived in these areas my whole life, and saw how it affected underserved populations. There was a story that needed to be told, so we’re telling it,” he said in an interview.
In a study, the researchers analyzed food access and cancer mortality data from 3,038 counties across the United States. The food access data came from the U.S. Department of Agriculture Food Environment Atlas (FEA) for the years 2012, 2014, 2015, 2017, and 2020. Data on obesity-related cancer mortality came from the Centers for Disease Control and Prevention for the years from 2010 to 2020.
Food desert scores were calculated through data from the FEA, and food swamp scores were based on the ratio of fast-food restaurants and convenience stores to grocery stores and farmers markets in a modification of the Retail Food Environment Index score.
The researchers used an age-adjusted, multiple regression model to determine the association between food desert and food swamp scores and obesity-related cancer mortality rates. Higher food swamp and food desert scores (defined as 20.0 to 58.0 or higher) were used to classify counties as having fewer healthy food resources. The primary outcome was obesity-related cancer mortality, defined as high or low (71.8 or higher per 100,000 individuals and less than 71.8 per 100,000 individuals, respectively).
Overall, high rates of obesity-related cancer mortality were 77% more likely in the counties that met the criteria for high food swamp scores (adjusted odds ratio 1.77). In addition, researchers found a positive dose-response relationship among three levels of both food desert scores and food swamp scores and obesity-related cancer mortality.
A total of 758 counties had obesity-related cancer mortality rates in the highest quartile. Compared to counties with low rates of obesity-related cancer mortality, counties with high rates of obesity-related cancer mortality also had a higher percentage of non-Hispanic Black residents (3.26% vs. 1.77%), higher percentage of adults older than 65 years (15.71% vs. 15.40%), higher rates of adult obesity (33.0% vs. 32.10%), and higher rates of adult diabetes (12.50% vs. 10.70%).
Possible explanations for the results include the lack of interest in grocery stores in neighborhoods with a population with a lower socioeconomic status, which can create a food desert, the researchers wrote in their discussion. “Coupled with the increasing growth rate of fast-food restaurants in recent years and the intentional advertisement of unhealthy foods in urban neighborhoods with [people of lower income], the food desert may transform into a food swamp,” they said.
The findings were limited by several factors including the study design, which did not allow for showing a causal association of food deserts and food swamps with obesity-related cancer mortality, the researchers noted. Other limitations included the use of groups rather than individuals, the potential misclassification of food stores, and the use of county-level data on race, ethnicity, and income, they wrote.
The results indicate that “food swamps appear to be a growing epidemic across the U.S., likely because of systemic issues, and should draw concern and conversation from local and state officials,” the researchers concluded.