Researchers from Iran show in the first human trial that probiotics appear to improve brain cognition in humans. The study, “ Effect of Probiotic Supplementation on Cognitive Function and Metabolic Status in Alzheimer's Disease: A Randomized, Double-Blind and Controlled Trial ,” was published in the open-access journal Frontiers in Aging Neuroscience . While probiotics (live bacteria and yeast dietary supplements that are good for your health, especially your digestive system) offer partial protection against several disorders, such as inflammatory bowel disease, allergies, and periodontal disease, their effect on cognition remained a hypothesis. This is because researchers discovered a communication platform between the intestinal microbiome, the gastrointestinal tract, and the brain. This two-way communication is mediated through the nervous system, the immune system, and hormones, and is known as the "microbiota-gut-brain axis." Studies with mice showed that probiotics improve learning and memory and reduce anxiety and depression- and obsessive-compulsive disorder-like symptoms. The evidence for these effects in humans, however, remained limited. Here, a team of scientists at Kashan University of Medical Sciences in Iran and Islamic Azad University in Tehran, Iran, performed a randomized, double-blind, clinical trial with Alzheimer's patients. They recruited a total of 52 women and men between the ages of 60 and 95 with Alzheimer's disease and tested the effects in patients’ cognition after treatment with probiotics. Half the patients were