by Heather Smith
Flatulence or gas can be annoying and embarrassing, but it is something everyone experiences in varying degrees. The good news is that you do not have to endure it. Well, at least not all the time.
Causes of Gas
The first step toward lessening gas is learning what causes it. Most intestinal gas in healthy people results from bacterial fermentation in the colon. Complex carbohydrates are the cause of the rectal gas we pass. These include certain sugars, starch, and fiber.
A normal diet contains a lot of carbohydrates that aren't digested by enzymes in the small intestine. Instead, they are dumped into the colon. These carbohydrates end up in the colon everyday, where they're digested by bacteria. This fermentation by bacteria gives off gas.
The meanest gas-producing carbohydrates, raffinose and stachyose, are found in beans. These include kidney beans, lima beans, black beans, navy beans, and soybeans.
Lactose, which is found mostly in milk and dairy products, can also cause excess gas in some people. People who do not have enough of the enzyme lactase, which digests lactose, experience gas. This condition, known as lactose intolerance, is much more common among people of Asian, Native American, and African decent, than among people of European decent.
The sugars fructose and sorbitol are also gas producers of the carbohydrate clan. Fructose is found in many fruits and vegetables. Sorbitol is found in fruits, including apples, peaches, and pears. Sorbitol is also an artificial sweetener commonly used in sugar-free food products and candy.
Starches and Fiber
Aside from sugars, starch and fiber camp out in the colon too. Starches include potatoes, pasta, and rice. (Rice does not lead to gas, though.) Soluble fiber found in oat bran, beans, peas, and most fruits can also give off gas.
You probably knew that eating food causes gas, swallowing air is one of the most common causes of gas. It can be caused by eating quickly and taking in large amounts of air.
Swallowed air primarily escapes through belching, not through the rectum, but some can still get all the way through.
Air swallowing can also be completely unrelated to eating. Other causes of swallowed air, according to gastroenterologists and dietitians, include the following:
Odor Producing Gas
Of all the gas we pass, researchers estimate that a very small amount is actually odor producing. Odorless gas consists of nitrogen, oxygen, hydrogen, methane, and carbon dioxide. Researchers suspect that odorous gas consists of sulfur compounds.
Normal Amounts of Gas
The average person passes gas 14 times a day. In fact, passing gas less than 25 times a day is considered normal.
How to Reduce Gas
Take these 5 steps towards reducing flatulence:
When to See a Doctor
Call your doctor if you have:
It may not be the easiest subject to talk about, but only your doctor can rule out serious health problems.
American Gastroenterological Association
Eat Right—American Academy of Nutrition and Dietetics
The Canadian Association of Gastroenterology
Dietitians of Canada
Gas in the digestive tract. National Institute of Diabetes and Digestive and Kidney Diseases website. Available at:
...(Click grey area to select URL)
Accessed September 26, 2017.
Preventing gas and flatulence. Harvard Medical School website. Available at:
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Updated October 2007. Accessed September 26, 2017.
Last reviewed September 2017 by EBSCO Medical Review Board Michael Woods, MD, FAAP
Last Updated: 9/22/2015
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