What gas does a human release when passing gas?
Apr 27, 2025
Source: Cainiu Health
Dr. Shen Yonghua
Introduction
In general, flatulence refers to the release of gas from the digestive system through the rectum. The gas expelled during flatulence mainly consists of odorless gases such as nitrogen, carbon dioxide, hydrogen, methane, and hydrogen sulfide, which contributes to the unpleasant smell. It is important to maintain a balanced diet and reduce the intake of foods that are prone to producing gas. These foods are typically rich in fermentable carbohydrates, which can increase gas production in the intestines.
Generally speaking, flatulence refers to the discharge of gas, mainly composed of odorless gases such as nitrogen, carbon dioxide, hydrogen, methane, and odoriferous gases like hydrogen sulfide. The detailed composition is as follows:
1. Nitrogen
Nitrogen is the primary component of flatus. It is an odorless gas, and some swallowed air and bacterial activity in the intestines may produce nitrogen during the digestive process.
2. Carbon Dioxide
Carbon dioxide is also present in relatively high amounts in flatus. It is a byproduct of the respiration process, and bacterial activity in the intestines may also produce carbon dioxide.
3. Hydrogen
Hydrogen also constitutes a certain proportion of flatus. It is mainly produced by intestinal bacteria when they break down food residue, especially when the food contains indigestible fibrous carbohydrates, which are fermented by bacteria to produce hydrogen.
4. Methane
Methane is another common gas found in flatus. It is primarily produced by methanogenic bacteria in the intestines, which break down food residue under anaerobic conditions to produce methane. The production of methane is closely related to the types and quantities of intestinal microbiota.
5. Hydrogen Sulfide
Although gases with unpleasant odors, such as hydrogen sulfide, are present in relatively small amounts in flatus, they play a decisive role in its odor. These odoriferous gases are mainly produced by intestinal bacteria when they break down proteins.
In daily life, attention should be paid to dietary structure, and intake of gas-producing foods should be reduced, such as legumes, onions, potatoes, and sweet potatoes. These foods are rich in fermentable carbohydrates that increase gas production in the intestines. At the same time, it is important to develop good eating habits, as chewing food thoroughly and eating slowly can help reduce the amount of swallowed air, preventing excessive air from entering the gastrointestinal tract and thus reducing the frequency of flatulence.
