On average, each person farts 14 times a day, emitting 0.5-1.5 liters of gas. Why does fart smell? Nitrogen, hydrogen, carbon dioxide, methane, and oxygen account for 99% of the components of farts, and they are odorless. The real odor comes from the remaining 1%: ammonia, hydrogen sulfide, indole, manure odor, volatile amines, volatile fatty acids, etc. Therefore, the cause of the fart smell is that some factors cause the gas concentration to increase by more than 1%, including the following factors:

The protein ingested by the human body is mainly digested into amino acids in the small intestine and absorbed by the body. If the protein is not fully digested due to excessive protein intake or insufficient protease, it will ferment and rot when it enters the large intestine, which will increase the content of hydrogen sulfide, indole and fecal odor in the fart, making the fart smelly. High-protein foods are generally meat, eggs, etc. , which used to be a more premium ingredient. The so-called "the more you eat, the more delicious and smellier it becomes." Therefore, in an era of material scarcity, it is generally the rich who stink. Of course, with today's emphasis on healthy eating, this rule has been broken.

People often say that eating too many beans will make you fart, and it’s true. What's going on? Originally, there are many types of sugars in beans, one of which is called "oligosaccharide", which cannot be destroyed by human stomach acid and cannot be absorbed by the human body. When they arrive in the large intestine, they are "warmly received" by the sweet-toothing microbes there. These delightful microorganisms ferment sugar to produce hydrogen and carbon dioxide. This gas disperses in the lower intestine, causing swelling. Then, like thunder, they will search for the nearest exit, which they will carry out, thus forming a fart. Surprisingly, many herbivores don't have this problem. The reason is that they have a catalyst called "a-galactosidase" in their bodies that can break down these oligosaccharides.

Generally speaking, soybeans contain stachyose and raffinose, which are considered to be the main causes of flatulence, but these two free sugars are beneficial to the reproduction and health of intestinal bifidobacteria. It should be pointed out that fermented soy products, such as broad beans, generally do not cause flatulence.