Symptoms of undigested food and particularly foul-smelling gas are mainly caused by poor diet and indigestion. First of all, dietary factors, usually eat too much, overeating and intake of a lot of spicy, raw and cold, stimulating food, will cause great pressure on the digestive system, resulting in the phenomenon of indigestion. Secondly, dyspepsia and gastrointestinal dysfunction caused by their own digestive system has a functional disorder, resulting in slowing down of peristalsis, so that a large amount of food can not be decomposed and absorbed in a timely manner, resulting in food residues remain in the intestines for a long period of time, and the fermentation will be particularly smelly phenomenon of exhaust gas. In addition, the imbalance of intestinal flora will also easily cause indigestion and the symptom of smelly gas.