Farting (or flatulence) is a normal process. In fact, everyone farts 13-20 times a day! But at some point, we’ve all experienced those smelly "silent but deadly" farts, and in this video, gastroenterologist Dr. Ugo Iroku explains why. Ever heard of sulfur? It’s a bad-smelling gas found in foods like broccoli, apples, celery, and cauliflower – and oftentimes the culprit of those deadly toots. Other reasons you’re passing gas may be a low-fiber diet, constipation, lactose intolerance, or even antibiotics. Plus, find out the answer to everyone’s biggest question about cutting the cheese: Are the deadly farts always the silent ones?