Mint leaves are widely used as a digestive aid. Peppermint leaf oil relaxes the muscular lining of the digestive tract, relieving cramps and gas and alleviating indigestion, according to naturopath Michael T. Murray, author of The Encyclopedia of Healing Foods. A double-blind study published in the May 2010 issue of the journal Digestive Diseases and Sciences found that enteric-coated peppermint oil significantly reduced abdominal pain and improved the quality of life for patients with irritable bowel syndrome. Participants took one capsule of the mint supplement three times per day for eight weeks. .