Depression is an emotional state characterized by low mood, anhedonia, feelings of hopelessness, insomnia and even loss of appetite. It is considered one of the main types of mood disorders. 1 Anxiety is another emotional state with clinical features of fear, worry, tension, and even physical changes such as palpitations and tremors without an obvious cause. 1 The Institute of Health Metrics and Evaluation 2 described both diseases as the most common mental disorders in human health with over 280 million people in the world suffering from these disorders. As the number of sufferers rises, so does the need to explore more efficient therapies for the management of mood disorders. Aside the conventional approach (that is, the currently used medications), there are indications that gut-microbiota play a major role in the regulation of mood and behaviours.