IL6 and major depressive disorder: The effectiveness of L. reuteri NK33 and B. adolescentis NK98 in decreasing stress, anxiety, and sleep disturbances, as well as measuring some blood biomarkers, particularly pro-inflammatory cytokines like IL-6, was demonstrated in a double-blind, randomized, placebo-controlled clinical trial that included 156 healthy individuals between the ages of 19 and 65 who had undergone psychological stress and had subclinical symptoms of depression or anxiety.