In a study by French researchers the oral administration of lactobacillus acidophilus, a bacterium commonly found in yogurt, induced the formation of opioid and cannabinoid receptors in intestinal cells, and mediated pain relieving functions in the gut, which are similar to the effects of morphine. They concluded that these results suggest that the microbiology of the intestinal tract influences our perception of the belly, and "suggest new approaches for the treatment of abdominal pain and irritable bowel syndrome." (Source: Rousseaux C, et al. Nat Med. 2006 Dec 10; [electronic publication ahead of print])