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Current Health Reports

Fighting Flatulence

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.

What Causes Gas?    TOP

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.

Beans    TOP

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    TOP

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.

Other Sugars    TOP

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    TOP

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.

Swallowing Air    TOP

You probably knew that eating food causes gas, but what about eating air? Air swallowing is one of the most common causes of gas, and 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:

  • Anxiety
  • Smoking
  • Chewing gum
  • Loose dentures
  • Drinking carbonated beverages
  • Drinking through straws

What Makes Gas Smell?    TOP

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.

What Is a Normal Amount of Gas?    TOP

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    TOP

Take these 5 steps towards reducing flatulence:

  • Avoid gas-producing foods at inconvenient times —Do not cut them from your diet completely. Most gas-producing foods are very healthy.
  • Introduce fiber slowly — Gradually introduce fruits, vegetables, and whole grains to your diet. You may want to start off eating 1-2 and vegetables a day for a week. You should then up your fiber intake to 5 servings of fruits and vegetables a day over the next week or so. Remember to drink at least 6-8 glasses of water a day to help prevent constipation.
  • Try taking a digestive aid like Beano or lactase enzymes Beano is an enzyme that is available over-the-counter. This digestive aid may be able to break down certain starches, reducing flatulence. Lactase enzyme taken before eating foods with lactose may help digest this carbohydrate in the stomach, avoiding digestion in the colon and flatulance.
  • Keep a food diary —Write down what you eat and how it affects you. You may be able to determine what is causing you to have excess gas, then modify your diet accordingly.

Should I See a Doctor For My Gas?    TOP

Call your doctor if you have:

  • Worsening flatulence that bothers you, or that suddenly changes
  • New flatulence, especially if you are over the age of 40
  • Severe gas pains or other symptoms, such as weight loss associated with the flatulence

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. American Gastroenterological Association website. Available at:
...(Click grey area to select URL)
Accessed September 22, 2015.
Gas in the digestive tract. National Institute of Diabetes and Digestive and Kidney Diseases website. Available at:
...(Click grey area to select URL)
Updated January 2, 2013. Accessed September 22, 2015.
Preventing gas and flatulence. Harvard Medical School website. Available at:
...(Click grey area to select URL)
Accessed September 22, 2015.
Last reviewed September 2015 by Michael Woods, MD
Last Updated: 9/22/2015
This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition. To send comments or feedback to our Editorial Team regarding the content please email us at healthlibrarysupport@ebscohost.com. Our Health Library Support team will respond to your email request within 2 business days.

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