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The Immune Mind: Linking Dietary Patterns, Microbiota, and Psychological Health

Summary

This review shows that what we eat significantly affects our mental health through our gut bacteria and immune system. Mediterranean-style diets rich in vegetables, whole grains, and healthy fats can help reduce depression and anxiety symptoms. Conversely, ultra-processed foods with added sugars and artificial ingredients increase the risk of mental health problems. Specific probiotic supplements may also provide modest benefits for mood by promoting beneficial gut bacteria.

Background

Depression and anxiety are leading causes of global disability. Recent evidence suggests that diet influences mental health through the gut-brain axis, microbiota composition, and immune-inflammatory signaling. Three key dietary domains have emerged with therapeutic potential: Mediterranean-style diets, ultra-processed food exposure, and psychobiotic interventions.

Objective

To systematically review recent clinical evidence (2020-2025) on Mediterranean diet interventions, ultra-processed food exposure, and psychobiotic/prebiotic strategies for depression and anxiety in adults. The review aimed to integrate mechanistic insights with clinical findings to provide practical recommendations for translating nutritional psychiatry into clinical practice.

Results

36 studies were included (14 RCTs, 9 cohorts, 13 systematic reviews/meta-analyses). Mediterranean diet interventions significantly reduced depressive symptoms with moderate-quality evidence. Ultra-processed food consumption was consistently associated with 25-40% higher depression risk. Psychobiotics showed small-to-moderate benefits on depressive symptoms through mechanisms involving short-chain fatty acids, inflammatory modulation, and tryptophan-kynurenine pathway regulation.

Conclusion

Mediterranean-style dietary patterns, reduced ultra-processed food intake, and targeted psychobiotic supplementation may complement standard psychiatric care for depression and anxiety. These approaches act through shared immune-metabolic pathways. Future research should prioritize longer, adequately powered randomized trials with standardized protocols, mechanistic biomarkers, and microbiome-informed stratification to clarify responders and establish causality.
  • Published in:Nutrients,
  • Study Type:Systematic Review,
  • Source: 41515213
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