What is gas?

Intestinal gas (flatus) comes from two main sources: 90% from swallowing air and 10% from fermentation of foods by intestinal bacteria. Most healthy people pass between one and three pints of gas per day, and experience episodes of flatus about 15 times every day!

The composition of flatus is mostly odorless gases: nitrogen, carbon dioxide, hydrogen, methane, and oxygen.

Everyone swallows some air every day, in the course of talking or eating, or sometimes just as a nervous habit. Most people are unaware that they are doing this, so they cannot stop themselves from swallowing air.

Most of this swallowed air is burped or belched up, but some finds its way into the intestine. The 10% of intestinal gas produced in the large intestine (colon) by fermentation of carbohydrates is mostly due to incomplete digestion of starches and certain sugars, which are contained in many foods including milk, beans, dark beer, red wine, onions, and certain fruits.

Continue Learning about Digestive Health

Digestive Health

Digestive Health

The digestive system includes all parts of the body that process food and expel waste, from your mouth to the end of your digestive tract. Diseases of the gastrointestinal tract prevent your body from effectively using the food yo...

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.