Meditation has been studied for many conditions, but the studies are rife with inconsistencies, and the benefits found are often modest. A randomized controlled trial of 75 women with irritable bowel syndrome, for example, reported that mindfulness meditation, the best-studied type of meditation, reduced the severity of symptoms. But a 2013 review of the literature concluded that the training did not curb anxiety or depression for I.B.S. patients and that improvements in quality of life and pain were small.