In theory, “peppermint oil reduces abdominal pain by targeting specific pain receptors,” says Adrian Masclee, a professor of gastroenterology and hepatology at the Maastricht University Medical Center in the Netherlands. It also may act as a muscle relaxant, he points out. Does it help manage indigestion? But Masclee is skeptical that peppermint oil helps people with indigestion, as one industry-funded study reported. That’s because the study used enteric-coated capsules, which don’t release the oil in the stomach, where indigestion strikes. “If you encapsulate the peppermint oil, it will only be released in the small bowel,” he explains. But Masclee doesn’t recommend uncoated peppermint oil capsules. “Because peppermint oil has a muscle-relaxing effect, it may reduce the tone of the sphincter between the stomach and esophagus,” he says. “That can cause reflux in some people.”