You already know that chocolate can do wonders for a dark mood -- but... yogurt? If you buy the kind that contains active probiotics, it may indeed brighten your spirits. A new study from Canada demonstrated that probiotics can help modulate anxiety. The study involved 35 patients with chronic fatigue syndrome (CFS) who experienced a host of gastrointestinal problems, including irritable bowel syndrome (IBS) and constipation. Participants were divided randomly into two groups, one taking a probiotic drink containing Lactobacillus casei strain Shirota (LaS), and the other taking a placebo that was identical in taste and appearance but had no probiotics. Results: After two months, the probiotic group had a significant decrease in anxiety symptoms, while the placebo group did not. The probiotic group also showed a significant increase in Bifidobacteria, which are beneficial for gastrointestinal health, compared with the placebo group. Intestinal Flora and Your Brain A. Venketeshwer Rao, MSc, PhD, the study author and professor emeritus of nutritional science at University of Toronto, says that there has been skepticism in the medical world about the role intestinal flora plays in the system of gut-brain communication (the enteric nervous system, often called "the second brain"). He said that this study provides evidence that through their metabolism in the gut, probiotic bacteria can boost levels of the mood-elevating chemicals tryptophan (an amino acid) and serotonin (a neurotransmitter). He added that the regions of the brain affected by CFS also house anxiety and depression. "These parts of the brain seem to respond to changes in the microflora, and most of our behavior patterns are controlled by these areas," he says. Dr. Rao says there still is much to learn about the role of gut flora. But many, if not most people, could improve their health by taking probiotics. The study used a probiotic drink, but Dr. Rao says that probiotic supplements may be even more effective, depending on what types and how many of the live microbes they contain. He advises looking for a product that contains Lactobacillus Shirota and Bifidobacteria, with 100 to 120 billion live probiotic bacteria. Source(s): A. Venketeshwer Rao, MSc, PhD, professor emeritus of nutritional science, University of Toronto.