The concept of a ‘gut-brain axis’ was recently developed when the complex communications between the brain and the gut became evident. The interaction may affect emotions, motivation, mood, and higher cognitive functions as well as gut homeostasis. Human microbe symbiosis’s merits are now acknowledged to transcend human mental health. Research has recently indicated that the gut-brain axis plays a vital role in brain health maintenance. The term ‘gut-brain axis’ can only partially capture the intricacy of these interactions. Dysbiosis of the gut commensals has been seen in patients with psychiatric diseases, such as depression. Major depressive disorder is caused by complicated interactions between the individual gene and the environment. In a forced swimming test, P. Zhenget al.discovered that germ-free mice with no gut microbiota had a shorter immobility duration than healthy mice. More radical effects were expressed on the use of probiotics rather than prebiotics and postbiotics in reducing the symptoms of depression in patients with major depressive disorder. One of prime importance can be given to exploring more microbiota to investigate the better therapeutic effects of probiotics, prebiotics, and postbiotics.