The reason for eating onions and having smelly farts is the production of sulfur compounds in the intestinal tract, which produces the phenomenon of increased exhaust. Onions are spicy food, after entering the gastrointestinal tract after digestion and decomposition will produce foul-smelling sulfide, so the phenomenon of foul-smelling farts, because the onion is also easy to stimulate intestinal peristalsis, so the exhaust increased. Eating onion farts is generally a normal phenomenon, not caused by disease. The nutritional value of onions is relatively rich, containing a variety of trace elements, dietary fiber, vitamins, etc., very beneficial to human health can be consumed in moderation. If you have chronic gastritis, peptic ulcer, chronic enteritis such patients try to eat less onions, you can use other vegetables instead of onions.