Feeling bloated after eating and passing excessive gas often leads people to cut out milk, beans or other foods, or to try one probiotic product after another. But if bloating, excessive gas and even diarrhoea continue to recur, the problem may involve bacteria in the small intestine rather than simply "too much gas".
Small intestinal bacterial overgrowth (SIBO) occurs when the number or type of bacteria in the small intestine becomes abnormal. This can lead to excessive fermentation of nutrients and symptoms such as bloating, abdominal pain, excessive gas and diarrhoea.
In some cases, nutrient absorption may also be affected, resulting in weight loss or nutritional deficiencies.
The difficulty is that these symptoms overlap considerably with conditions such as irritable bowel syndrome and lactose intolerance. Bloating alone therefore cannot confirm a diagnosis of SIBO.
A doctor will consider the medical history, symptoms and individual risk factors before deciding whether a breath test or other investigations are appropriate. Management is not simply a matter of taking more probiotics. It is also important to understand why the bacterial overgrowth has occurred and address the underlying cause.
When persistent "gas" has no obvious explanation, the more useful question may be whether something in the digestive system itself has changed.
