Background

In the US, there has been a documented increase in the population of older adults and their life expectancy over the last decade [1, 2]. In the next decade, older adults will represent 21% of the US population; their average life expectancy is estimated at 81.7 years in 2030, compared to 79.7 years in 2017 [1, 2]. Successful aging has been conceptualized as a descriptive measure for the quality of aging [3], aiming to reduce morbidity, optimize cognitive and functional capacities, and improve social engagement [4]. In particular, healthy nutrition is one of the core lifestyle approaches needed in public health programs to promote successful aging [5].

Food insecurity is a pressing public health concern for older adults [6,7,8,9,10,11]. In 2021, food insecurity was reported by 7.1% of US households with an adult ≥ 65 years and by 9.5% among adults ≥ 65 years living alone [12]. These figures reflect a substantial increase in food insecurity among older adults over the last 20 years [13]. Food insecurity disproportionately affects older adults who live alone, have fixed incomes, and suffer from chronic health conditions [6,7,8,9,10,11, 14]. Studies have shown that food insecurity is not only a critical risk factor for suboptimal dietary and health behaviors and physical health [15, 49], further studies should examine the role of other health programs for older adults in influencing the association between food insecurity and health outcomes among older adults.

This study has some limitations. First, due to the cross-sectional nature of the data, we are unable to infer any causal relationships between food insecurity, health-related quality of life among older adults. Even though household food security status was assessed over the past year and health outcomes were reported over the past month, reverse causation remains plausible because some of the outcomes we examined may also influence food security status [24]. Longitudinal studies are needed to understand the direction of the association among older adults. Second, the possibility of unmeasured confounding could not be ruled out. Factors like transportation needs, neighborhood access to food stores, household assets to purchase food other than income, and social support were not measured in NHANES.

Another limitation is that the USDA HFSSM was developed primarily from research with caregivers with young children as the reference. Older adults may face unique barriers to food acquisition (e.g., functional limitations, health conditions, social isolation) that are not captured in the current measure, which primarily focuses on economic restraints. While the HFSSM is the gold standard for food insecurity assessment in the US context, the prevalence of true food insecurity in the study population may be underestimated. We acknowledge that we examined the potential role of SNAP/Food Stamp, which is only one of the federally funded programs for older adults in the US collected in the NHANES; therefore, our findings could not be extrapolated to other federally funded programs, such as the Older Americans Act [49]. Thus, further studies should examine the role of other health and nutrition programs in influencing the association between food insecurity and health outcomes among older adults.

Moreover, because of the small sample, we were limited from examining all four groups of food security (i.e., food security, marginal food security, low food security, and very low food security); thus, future studies with larger sample sizes to examine the dose-response nature of these associations across the four groups of food security are warranted. Also, due to some degree of sensitivity in reporting household food security information and mental health, we acknowledge that our self-reported data might be subject to social desirability bias. However, this would report an under-reporting of food insecurity and poorer physical and mental health outcomes, which would suggest that the reported estimates are attenuated compared to the true estimates. Further studies are needed to confirm these associations among older adults in different geographic and socio-political contexts.

Conclusions

In conclusion, we showed that food insecurity was associated with poorer health-related quality of life among US older adults aged ≥ 60 years. To a lesser extent, positive associations were also observed between marginal food security and some health-related quality of life outcomes. There was some evidence of heterogeneity in these associations by sex, but not by participation in the SNAP/Food Stamp program. Further research is needed to examine the underlying mechanisms linking food insecurity and the physical and mental health outcomes observed in the current study and explore the potential of diet quality and other modifiable risk factors to ameliorate the adverse associations between food insecurity and poor mental health among older adults.