Unpacking the "black box" of global food insecurity and mental health.

Food insecurity is a global concern. While it was once characterized mainly as a problem of undernutrition, it is now recognized that a person may be food insecure without experiencing hunger. Numerous studies have demonstrated that food insecurity is strongly related to poor mental health around the world, but the mechanisms that underpin that relationship remain poorly understood. One body of research from nutritional sciences posits that nutrient deficiency impacts brain function, producing symptoms of depression and anxiety. Another body of research from the social sciences posits that the social consequences of having to eat non-preferred foods or obtain food in socially unacceptable ways may compromise mental health through stress. This study was designed to clarify the mechanisms linking food insecurity and mental health using case studies in rural Brazil and urban Ethiopia. Working with samples consisting of about 200 adult household decision-makers (mostly female) recruited between 2015 and 2019 at each site, we tested for nutritional and social mediation of the food insecurity-mental health relationship using multivariable linear regression and mediation analysis. Our analyses found no evidence of mediation in either setting. Moreover, there was no association between nutritional status variables and food insecurity. These findings suggest that food insecurity likely impacts mental health directly through forms of basic needs deprivation, such as worrying about where one's next meal will come from, rather than by acting as a social signal or even by impacting nutritional status. These results underscore the power of basic-needs deprivation for impacting mental health.