Gut microbiota, probiotics and their relationship with major depressive disorder: a literature review

Major depressive disorder (MDD) has gained relevance in recent years, as it is one of the main causes of disability worldwide and has a significant impact on the daily lives of those who experience it. The relationship between gut dysbiosis and MDD has emerged as a crucial component in the field of mental health. The gut microbiota, which encompasses a wide diversity of microorganisms, establishes a bidirectional connection with MDD through the microbiota-gut-brain axis, neuroinflammation and alteration of brain function. The objective of this work was to analyze the relationship between problems with the balance of microorganisms in the intestine (a phenomenon known as "dysbiosis") and MDD. A qualitative approach was adopted that combined bibliographic and descriptive analysis, prioritizing primary sources in psychology, neuroscience and microbiology. Research in English and Spanish from 2019 to 2023 was examined using recognized search engines and databases. In this context, it was observed that the use of probiotics has become increasingly relevant as part of complementary treatment for MDD. Probiotics, such as Lactobacillus plantarum DP189 and the bacteria Roseburia intestinalis, have a positive impact on the intestinal microbiota, blood-brain barrier integrity, and neurotransmitter production. The review highlights the crucial role of gut microbiota in MDD and the promising utility of probiotics as a complementary treatment. This suggests new therapeutic perspectives and underlines the importance of future research to better understand this complex interaction.