A randomized, double-blinded, placebo-controlled trial conducted in Iran with MDD patients showed that treatment with the probiotics Lactobacillus acidophilus, Lactobacillus casein, and Bifidobacterium bifidum improved depressive symptoms’ total scores, while also reducing inflammation by decreasing insulin resistance and serum CRP levels when compared to placebo [298]. The gene discussed is CRP; the disease is major depressive disorder.