Abdominal distension occurs when substances, such as air (gas) or fluid, accumulate in the abdomen causing its expansion.

Through a variety of causes (see below), bloating is most commonly due to buildup of gas in the stomach, small intestine, or colon.

Studies have shown that swallowing air during eating or delayed emptying of the stomach from hyperacidity leads to bloating after a meal.

Poorly digested components of many foods are excreted into the large intestine where they are degraded by bacteria, producing excess gas.

Many vegetables are known to cause bloating due to high levels of fiber and undigestible sugars such as raffinose (e.g., beans, cabbage, broccoli).

[13] For some people, recurrent distension symptoms worsen their quality of life and thus many resort to health supplements or medications.

Dietary supplements containing various enzymes, for example Beano, are formulated to help break down complex carbohydrates and vegetables in order to reduce substances in the gut that cause bacterial overgrowth and subsequent bloating.