COVID-19: Researchers provides evidence of the link between food insecurity and increased risk of cardiovascular death

Food insecurity is one of the nation’s leading health and nutrition issues – about 13.7 million (10.5 percent) of households in the United States were food insecure at some time during 2019, a trend likely to increase in light of the COVID-19 pandemic.

According to preliminary research conducted by researchers at Penn Medicine, increasing rates of food insecurity in counties across the United States are independently associated with an increase in cardiovascular death rates among adults between the ages of 20 and 64.

The large-scale, national study, which will be presented at the American Heart Association’s Scientific Sessions 2020, provides evidence of the link between food insecurity and increased risk of cardiovascular death.

This is one of the first national analyses to evaluate changes in both food security and cardiovascular mortality over time, and to see if changes in food insecurity impact cardiovascular health. The findings were also published today in Circulation: Cardiovascular Quality and Outcomes.

“This research gives us a better understanding of the connection between economic distress and cardiovascular disease,” said Sameed Khatana, MD, MPH, senior author of the study and instructor of Cardiovascular Medicine in the Perelman School of Medicine at the University of Pennsylvania.

“What’s going on outside the clinic has significant impact on patients’ health. There are many factors beyond the medications we may be prescribing that can influence their wellbeing, food insecurity being one of them.”

Researchers analyzed data from the National Center for Health Statistics and the Map the Meal Gap study, to examine county-level cardiovascular death rates and food insecurity rates from 2011 to 2017, among adults age 20 to 64, and those 65 years and older.

The researchers found that while the overall food insecurity rates for the entire country declined between 2011 and 2017, the counties that had the most increase in food insecurity levels had cardiovascular death rates that increased from 82 to 87 per 100,000 individuals.

Additionally, for every 1 percent increase in food insecurity, there was a similar increase in cardiovascular mortality among non-elderly adults (0.83 percent).

“There has been a growing disparity when it comes to food insecurity, and this data demonstrates that parts of the country are being left behind.

Unfortunately, this may only get worse as the country grapples with the ramifications of the COVID-19 pandemic,” Khatana said. “However, interventions that improve a community’s economic wellbeing could potentially lead to improved community cardiovascular health.”

The authors intend to study whether interventions that improve food insecurity can lead to better cardiovascular health.

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Cardiovascular disease remains a leading cause of mortality in the United States (US) [1] with obesity being an important risk factor [2,3]. Both cardiovascular disease and obesity are interconnected, non-communicable diseases that are particularly burdensome among underserved and minority populations, including noted sex and race differences [4,5,6,7,8].

Efforts to better understand disparities in cardiovascular health and obesity have highlighted the role of social determinants. For example, a recent American Heart Association (AHA) scientific statement reinforces the important influence of social determinants such as socioeconomic position and race on cardiovascular disease risk [8].

Food insecurity has recently emerged as an important social determinant of health as evidence demonstrating its relationship with adverse health outcomes and health disparities continues to accumulate. Food insecurity is defined as the lack of “nutritionally adequate and safe foods” or the limited or uncertain “ability to acquire acceptable foods in socially acceptable ways” [9]. Food insecurity has been shown to be more prevalent in women [10] and racial minorities [11].

Importantly, food insecurity has been broadly linked to chronic disease [12,13,14] with a wealth of studies showing a strong association between food insecurity and obesity [15,16,17,18]. There is also evidence that food insecurity is related to poor cardiovascular health [19], as measured using the AHA Life’s Simple 7 (LS7) [20], and increased cardiovascular disease risk [12,21,22].

Cardiovascular disease research has also pointed to the importance of health literacy in understanding disease risks and outcomes [23,24,25]. Defined by the U.S. Department of Health and Human Services (HHS) and the National Academy of Medicine (NAM), health literacy is the “degree to which individuals have the capacity to obtain, process, and understand health information and services needed to make health decisions” [26,27].

Failure by providers and healthcare systems to account for deficits in these capacities may contribute to poor health outcomes. The AHA’s scientific statement addressing health literacy and cardiovascular disease calls for better integration of health literacy into management and prevention strategies targeting cardiovascular disease, especially given noted disparities in health literacy by sex and race [28].

Such calls to action are particularly relevant as studies have shown that low health literacy is associated with increased risk of cardiovascular disease [25], while high health literacy has been linked to lower body weight [29].

Given the aforementioned evidence, there is a need to recognize the interplay of multiple social determinants and health disparities in the relationship between food insecurity and health outcomes. The aim of the current study is to examine potential differences in the associations between food insecurity and cardiovascular health and measures of adiposity by sex, race, and health literacy status. This objective was carried out in a large sample of underserved adults with obesity.

Discussion
Using baseline data from a large cluster-randomized controlled trial in an underserved population with obesity, this study examined associations between food insecurity and cardiovascular health and adiposity. Importantly, this study explicitly focused on potential differences in these associations by noted disparities, including sex, race, and health literacy status.

Results indicated a number of significant differences, specifically in the relationship between food insecurity and adiposity. This included greater BMI and WC in food insecure women compared to women who reported being food secure. These findings are particularly relevant given a recent meta-analysis that found a robust positive association between food insecurity and obesity, with this relationship being most significant in adult women [16], as well as a smaller study that found a significant association between food insecurity and WC in a sample of low-income minority women [37].

Adiposity was further shown to be significantly greater in food insecure patients with better health literacy compared to patients who reported being food secure. This finding is interesting as research has largely shown a significant link between low health literacy and greater body weight in adults [29,38].

While similar differences in adiposity were not demonstrated between food insecure and food secure patients with low health literacy, this finding does highlight the significant and pervasive link between food insecurity and obesity [15,16]. Further, while better health literacy may support better health decisions and, in turn, improved health outcomes, better health literacy in the context of food insecurity may not be actionable, so that food insecurity maintains its deleterious health consequences.

Importantly, to the authors’ knowledge, this study was the first to examine the interaction between health literacy and food insecurity in relation to cardiovascular health and adiposity. Given this, more studies that examine the interconnected influence of food insecurity and health literacy on health outcomes are warranted, especially in other populations with different sociodemographic and health profiles.

The results did not demonstrate any significant associations between food insecurity and cardiovascular health metrics. Other studies that have found significant linkages between food insecurity and cardiovascular health were most often carried out in large, nationally representative samples and did not rely upon LS7 to measure cardiovascular health [12,21]. Only one other study has investigated food insecurity in relation to LS7 and it components [19].

This study found that being food insecure was significantly linked to a decreased likelihood of ‘good’ cardiovascular health (ideal and intermediate levels of LS7 total score combined) [19]. This study also found that, contrary to hypothesized expectations, those who reported food insecurity were significantly more likely to have ideal levels of blood pressure and total cholesterol [19].

Importantly, this study used data from a population-based representative sample of Wisconsin residents and a single question to assess food security status [19]. Further, their sample was predominantly White (85%) [19], while the PROPEL trial has greater racial diversity with a majority of African American patients (67%).

Such study-dependent complexities point to the fact that empirical evidence regarding food insecurity and cardiovascular health, LS7 in particular, is only beginning to accumulate and further investigations are needed to better explicate this relationship. The use of similar standardized measures of food insecurity and cardiovascular health would further aid in comparing and summarizing results from studies in this field.

No significant race by food insecurity interactions were found in the associations with cardiovascular health or adiposity. This is potentially due to the lack of significant differences between racial groups in cardiovascular health and adiposity measures within the sample (see Tables S1 and S2).

Further, the study sample is largely African American, which is a particularly unique attribute of this trial. While food insecurity was significantly disparate between racial groups, the lack of variation in the selected outcomes (i.e., a majority of patients had poor cardiovascular health) may have limited the ability to detect any significant race-based differences.

This is not to say that racial disparities in food insecurity, cardiovascular health, and adiposity are not important, but rather in this sample, sex and health literacy emerged as the more relevant social determinants when considering how food insecurity is linked to health outcomes. Further investigations in additional samples are warranted to better elucidate the complex interplay of multiple social determinants in shaping how food insecurity impacts various health outcomes.

This study has a number of key strengths. First, most data for the outcomes assessed in this study were derived from clinic- and laboratory-based assessments, with the exception of smoking, diet, and physical activity, which were collected via self-report questionnaires. Second, the PROPEL trial is being carried out in an underserved and largely minority (i.e., African American) population, which makes the results from the current study broadly generalizable to similar populations across the US [30].

Further, this trial is also being conducted in Louisiana, which has a significantly higher food insecurity rate (17.3%) than the U.S. overall (11.8%), but is comparable to other Southern states, including Arkansas, Mississippi, and Alabama, where food insecurity is also notably high [39].

This makes the current study particularly relevant within a state and region and that has a demonstrated need to better understand how food insecurity, as a prevalent health-related disparity, contributes to poor health. Results from this study certainly address this public health need.

Importantly, a few limitations are noted for this study. First, this was a cross-sectional investigation, which limits the ability to address causality between food insecurity and cardiovascular health and adiposity. Further, the purpose of the PROPEL trial is to test the effectiveness of an obesity treatment program, which potentially creates a self-selection bias among patients who are seeking such treatment and qualify to participate in the trial.

Subsequently, all PROPEL patients have obesity, which potentially limits variation in cardiovascular health and associated metrics as this sample may be largely unhealthier than samples observed in other studies or the general population. Third, while the REALM is one of the most widely used validated instruments to assess health literacy and the short form version reduces participant burden, some researchers have critiqued this tool as only an assessment of an individual’s ability to read and pronounce health-related words rather than accurately reflecting an individual’s level of health literacy [40].

Last, the interaction terms and subsequent stratified analyses assessed in this study create disparate patient numbers between subgroups (e.g., sex, race, health literacy). Smaller sample sizes within certain subgroups may potentially drive the significant or non-significant effects shown in this study.

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More information: The abstract will be presented in Session QU.AOS.765 Social Determinants of Cardiovascular Health on November 13, 2020, at 9:00 am CST/10:00 am EST.