Psychosocial Determinants of Young Adult Dietary Quality: Testing a Conceptual Model with Developmentally-Relevant Psychosocial Variables Considering Variations By Poverty-Level

Background and Purpose: Diet-related non-communicable diseases are associated with high mortality rates worldwide. Young adults are high-risk as they have the lowest dietary quality compared to other age groups (Akseer et al., 2017). Young adults are also vulnerable to multiple psycho-socioeconomic challenges such as food insecurity (Keith-Jennings & Palacios, 2017), poverty (Wilmer et al., 2019), and depression symptomatology (NIH, 2019). These variables are independently associated with food-related beliefs, values, and diet. However, little is known about (1) whether dietary quality is associated with food insecurity and depression through food-related beliefs and values, (2) whether there is a reciprocal relationship between food insecurity and depression, and (3) whether the strength of these paths varies by poverty. Accordingly, this study tested a model including these understudied relationships.

Methods: Path analyses were conducted using a nationally representative young adult subset (N=3535) from the National Health and Nutrition Examination Survey (NHANES), 2007-2010: the only waves that included food-related beliefs and values. Full Information Maximum Likelihood was used to treat missingness. The robust Huber-White estimator addressed nonnormality and heterogeneity of variance. Instrumental variables were included to examine the reciprocal relationship. Global and focused fit indices assessed model fit. Food security was measured by the USDA Household Food Security Survey. The beliefs and values items were designed for NHANES, capturing beliefs about the cheapness, nutritiousness, taste, convenience, and social utility of eating fast food/pizza and food at restaurants. Value items captured the importance of price, nutrition, taste, ease of prep, and ease of preservation when grocery shopping. Dietary quality was assessed using the Healthy Eating Index-2010 score ranging from 0 to 100 (100 indicated meeting dietary guidelines). Depression symptomatology was operationalized as the total score of the Patient Health Questionnaire-9. Poverty was captured by the family income poverty ratio pre-calculated by NHANES ranging from 0-5, where 5 indicated income at 500% of the poverty level. Demographics (gender, race/ethnicity, education, and body mass index) were included as covariates.

Results: Depression negatively predicted dietary quality. Furthermore, depression mediated the relationship between food insecurity and dietary quality, holding poverty constant. However, when poverty was included as a moderator, a reciprocal relationship emerged, where depression positively predicted food insecurity, particularly among lower-income young adults. Surprisingly, food insecurity alone did not predict dietary quality. Eating at restaurants to socialize and valuing nutrition when grocery shopping positively predicted dietary quality, holding poverty constant. The belief about the cheapness of restaurants negatively predicted dietary quality only among higher-income young adults.

Conclusions and Implications: The vicious cycle of food insecurity and depression aligns with previous studies describing the psychological hardship of food-insecurity: food insecure low-income young adults reported associating food insecurity with failing to be independent and, as a result, avoided help due to feeling ashamed. Pathophysiological perspectives were also considered. Findings support the need for destigmatizing and inclusive food assistance policies, particularly for low-income young adults. Furthermore, future research is needed to understand how young adult dietary interventions can address psychological burdens of food insecurity, protective mechanisms, and beliefs that vary by income.