Probiotics may not just prevent depression, but could also reduce its severity if you already have it. A clinical trial of Lactobacillus helveticus and Bifidobacterium longum tested the two over 30 days for their effects on the Hospital Anxiety and Depression Scale (HADS) and the Hopkins symptom checklist. They found significant decreases in the sub-spheres of depression, somatisation and anger-hostility. "Somatisation" refers to the physical symptoms that can come with depression. The researchers then analysed the results of those with urinary cortisol levels of less than 50ng/mL at baseline. Cortisol is one of the primary stress hormones. Probiotics still significantly reduced these symptoms, as well as the "obsessive-compulsive", "anxiety" and "paranoid-ideation" scores in the Hopkins checklist. It was also pointed out that probiotics, unlike pharmaceuticals, are not addictive, and do not cause memory or learning impairments. Overall, it looks like probiotics could be an effective way to manage mood disorders naturally, but it is always best to consult a qualified practitioner of natural medicine first.