This paper examines the ecological association of dietary food intake with mental health outcomes on the group level across countries. Published data from the World Mental Health Survey were used to compare lifetime prevalence of four categories of mental health disorders (anxiety disorders, mood disorders, impulse control disorders, and substance use disorders) with a country’s fish/seafood and sugar/sweetener supply quantity using the Spearman rank correlation. Data were compared for 17 countries across the world. Sugar and sweetener supply quantity was significantly and positively associated with anxiety disorders (rho = 0.75, p = 0.001), mood disorders (rho = 0.75, p = 0.001), impulse control disorders (rho = 0.78, p = 0.001), and substance use disorders (rho = 0.68, p = 0.007). Fish and seafood supply quantity had no significant association with any mental health disorders. Mental health disorders represent a significant health problem around the world. Public health measures aimed at improving the quality and availability of a nation’s food supply could have a significant positive impact on mental health. Further randomized studies are needed to further validate the study findings.