Purpose of Review <p>Depression and anxiety are among the most common global mental health conditions. Emerging research highlights the impact of diet and the gut microbiome on the nervous system and mood. We review and discuss the existing research on the effects of various diets—including high-fiber, fermented, ketogenic, and calorie-restricted diets—alongside the roles of prebiotics and probiotics, on anxiety and depression.</p> Recent Findings <p>While mostly observational, mounting data from randomized controlled trials support the idea that dietary modification can improve mental health outcomes by altering gut microbial composition and activity. The efficacy of supplements and probiotics in mood outcomes is conflicting. Additional research is needed to fully understand the mechanisms that link diet, the gut microbiome, and mental health. Overall, findings suggest that dietary modifications are feasible and beneficial in mild cases of anxiety and depression.</p> Summary <p>This review explores the bidirectional relationship between diet, gut microbiome, and mood disorders. Various diets are discussed, and their respective impact on mental health is reviewed. Challenges in food and mood research remain due to variability in research practices. Additional studies are needed to further explore the role of nutrition in optimizing mental health.</p>