Why Beans Cause Gas

Everyone passes gas about 14 times a day, and it can happen even while sleeping. Gas is part of the natural digestive process, and there's no getting around it. If gas isn't bothersome for any reason, it's typically not something to worry about. However, many people find gas embarrassing, particularly if passing an excessive amount of gas.

It is true that some foods may tend to make a person produce more gas than other foods. In particular, foods that have a high fiber content are a frequent offender when it comes to causing symptoms of gas and bloating.

It is also true that most people do not get enough fiber in their diet and should be eating more fibrous foods. One food that has an especially notorious reputation when it comes to gas is beans. Beans are well-known for their ability to cause flatulence, but the cause as to why may surprise you.

Intestinal gas is primarily composed of hydrogen, nitrogen, and carbon dioxide, all gasses that are, odorless. In about one-third of people, however, intestinal gas also contains another ingredient: methane.

It's unclear why some people's bodies produce methane and others do not. One way to tell if there is methane in gas is to look at stool: people who produce methane typically will have stools that float in water.

Beans (legumes) cause gas because they contain a particular sugar, called an oligosaccharide, that the human body can not break down fully. Oligosaccharides are large molecules and are not broken down and absorbed in the same way that other sugars are, by the normal digestive process that takes place in the small intestine. This is because the human body actually does not produce the enzyme that breaks down oligosaccharides.

By the same principle, other foods that come into the large intestine without being absorbed in the small intestine will cause gas. For example, stress can cause food to move through the digestive tract too quickly to be properly digested, resulting in the production of excess gas.

To prevent gas that is caused by eating beans or other foods, the oligosaccharides must be broken down before they reach the large intestine and become food for the resident bacteria that live there.

There is an enzyme that breaks down oligosaccharides, called alpha-galactosidase. This enzyme, which the human body does not make, is derived from the fungus Aspergillus niger and is available in pill form under the brand name Beano and others.

Alpha-galactosidase may also increase galactose levels in the blood and should not be used by those who have the genetic disease galactosemia.

As long as it's not causing pain or excessive bloating, gas is a normal and expected part of the digestive process. In fact, gas is an indication that things are going the way they should in the intestines.

Gas itself from diet won't cause any real harm, but taking steps to minimize gas can be used if it causes too much trouble. People who feel they truly have too much gas or discomfort from gas should talk to a doctor about how best to manage it.