People with IBD, which includes Crohn’s Disease and UC, often report feeling bloated. Many also worry about excess gas and its effects, such as tummy gurgles and passing flatus (breaking wind). 


There are several possible explanations for bloating and wind. A major cause of bloating is gas. Gas can be trapped in the stomach and intestines (bowels) to cause bloating, or can be expelled as wind (flatus).

Bloating is also a common symptom of Irritable Bowel Syndrome (IBS). This is a separate condition from IBD, but both UC and Crohn’s are associated with a greater risk of IBS. So it is quite possible for people with IBD also to have IBSlike symptoms. For example, an attack of UC may be followed by irritable bowel symptoms, including bloating, which may last for several months.

It has been suggested that bloating is more likely to occur if you have constipation. Eating a lot of fatty food can delay stomach emptying, and this too may cause bloating and discomfort. You may also experience bloating if you have adhesions (scar tissue) as a result of previous surgery.


It is normal to have gas in your intestine whether or not you have IBD. We all produce several litres of gas a day through the normal processes of digestion. Some of this is reabsorbed into the bloodstream and eventually breathed out, the remainder has to be expelled as wind. Most of us probably break wind on average 15 times a day, even if we are unaware of it.

One possible cause of excess gas is swallowing too much air when eating, drinking or talking (aerophagia). Certain foods and fizzy drinks can also contribute to this. Smoking can also contribute to the amount of air that you swallow. Some people swallow air as a nervous reaction.

Excess gas can also be caused by the normal bacteria in the colon producing too much gas when they break down certain foods. Foods containing complex carbohydrates, for example vegetables such as beans, cabbage and Brussels sprouts, are difficult for the human body to digest. They are broken down by the gas-producing bacteria instead. Foods that contain sorbitol, an artificial sweetener, can cause similar problems. Poor absorption of food by the small intestine (often common in Crohn’s Disease) means that more undigested food reaches the colon, where bacteria can digest it to produce even more gas.

Research has shown that people with Crohn’s in their small intestine are more likely to be lactose intolerant than people with UC or the general population. Lactose intolerance (difficulty with digesting lactose - a sugar found in milk) can cause gas. Lactose intolerance is caused by lack of the enzyme lactase in the intestine which means that the body cannot break down the lactose. Instead, it is fermented by the gas-producing bacteria in the colon.

It has also been suggested that some people may simply have more bacteria than others, or bacteria that produce more gas.