What Causes Gas and Bloating?

Gas and bloating are perhaps the most uncomfortable symptoms related to Sucrose Intolerance caused by Congenital Sucrase-Isomaltase Deficiency (CSID). But before we talk about what causes bloating and gas in people born with CSID, we have to first talk about the two different types of gas that occur in the gastrointestinal (GI) tract.

The first type is gas in the upper GI tract, mostly in the esophagus and, to a much lesser degree, in the stomach. Gas in the upper GI tract is caused by swallowing air. You might not realize it, but you swallow air every day. For instance, if you chew gum, smoke cigarettes, gulp down a drink or a meal, talk while you eat, or drink through a straw, you are swallowing air. Another cause of gas in the upper GI tract is carbonated drinks, such as sodas or beer. Gas in the upper GI tract is usually relieved by belching.

The type of gas that people with CSID are concerned about is gas in the lower GI tract, which is primarily in the large intestine. As embarrassing as it may be, everybody gets intestinal gas, also called “flatulence.” In fact, it is normal to “pass gas” a dozen or so times every day.

Intestinal gas is made up mostly of odorless chemicals in the form of gas – carbon dioxide, oxygen, nitrogen, hydrogen, and sometimes methane. The unpleasant odor from intestinal gas is actually caused by other gases, which are produced by bacteria in the large intestine. When food isn’t broken down and absorbed from the small intestine, the food moves on to the large intestine where bacteria break the food down. The smelly gas generated by bacteria is usually sulfur gas.

It is normal to have bacteria in the GI tract, mostly in the large intestine, the last part of the GI tract. The large intestine is where stools are formed, and water and minerals called “electrolytes” move out of the GI tract into the bloodstream.

So, what does intestinal bacteria have to do with your constant gas and bloating? Here’s where the complex sugars come in. If someone with CSID eats a food that contains sucrose, including starches that contain sucrose, they are not able to break that complex sugar into a simpler form that can be absorbed. So, instead of being absorbed from the small intestine, the complex sugars keep moving through the GI tract to the large intestine.

These complex sugars are broken down by the intestinal bacteria in the large intestine. The way intestinal bacteria breakdown complex sugars, such as sucrose, is by a process called “fermentation.” The byproducts of fermentation of complex sugars include the gases hydrogen and carbon dioxide. That is the cause of bloating and gas associated with CSID.

People who have CSID experience excess intestinal gas and abdominal bloating every time they eat a food that contains sucrose. The degree of discomfort they feel is determined in part by how much sucrose they eat at any time.

Of course, bloating and gas occur whenever someone with CSID eats a food containing sucrose. But a number of other foods may cause bloating and gas, even in people who have sucrase-isomaltase that works. Here’s a brief list of some examples:

  • High fiber foods: beans and peas, fruits, vegetables, and whole grains
  • Artificial sweeteners: sorbitol, mannitol, and xylitol
  • Cruciferous vegetables: cabbage, broccoli, Brussels sprouts, and cauliflower
  • Carbohydrates: bread, pasta, and rice

Sucrose Intolerance Is More Common Than You Think