Effect of Psychobiotics With Standard Antiddepressants in Treatment of Major Depressive Disorder

The goal of this clinical trial is to learn whether adding psychobiotics (a combination of Lactobacillus helveticus and Bifidobacterium longum) to standard antidepressant treatment works better than antidepressants alone for adults with major depressive disorder. The study will also learn about the safety of taking these psychobiotics with antidepressants. The main questions it aims to answer are: 1. Does adding psychobiotics lower depression symptoms more than a placebo (a look-alike capsule with no active ingredients)? 2. Is it safe and well tolerated when taken with standard antidepressant treatment? Researchers will compare psychobiotic capsules with placebo capsules to see whether psychobiotics improve depression symptoms when used together with standard antidepressants. Participants will: 1. Continue taking their prescribed antidepressant medicine. Be randomly assigned to receive either a psychobiotic capsule or a placebo capsule once daily for 6 weeks. 2. Complete depression assessments at the start of the study and again at 3 and 6 weeks. 3. Attend regular follow-up visits so researchers can monitor symptoms, side effects, and overall progress