Vast is the spectrum of foods that can trigger digestive problems: spicy foods, chocolate, peppermint, citrus, tomato-based foods, mustard, chili, and raw onions are all thought to irritate the lining of the esophagus. But what’s the major dietary factor in causing reflux? “Eating large, fatty meals,” says Jeffrey Alexander, MD, head of the Esophageal Clinic at the Mayo Clinic. That’s because fat softens the sphincter muscles, which seal off the lower esophagus. Without a tight seal, stomach acids can back up into it. Be sure to eat foods rich in fiber, the dinner of choice for gut-friendly bacteria.