Small Intestinal Bacterial Overgrowth is, as the name suggests, when the wrong bacteria or too many bacteria grow in the small intestine.
The small intestine is the longest part of your gastrointestinal tract at about 6 metres long and is where your food mixes with digestive juices and bile. Food usually moves through the small intestine quite quickly, with minerals and nutrients being absorbed along the way. Relatively few bacteria live in the small intestine in healthy individuals.
With SIBO the excess bacteria feed on the contents of the small intestine and can produce chemical and gaseous byproducts, potentially leading to a range of nonspecific symptoms including bloating, nausea, diarrhea, always feeling full, or loss of appetite. The non-specificity of these symptoms can make it hard to diagnose SIBO.
SIBO is generally not yet well understood. It can happen in conjunction with or as a complication of a wide range of other illnesses. If you think you might be affected you should speak to your doctor or a registered dietician as soon as possible.
Who does SIBO affect?
SIBO can occur for lots of reasons. If your gut motility is impaired, perhaps because of a stricture, as a result of diet, following abdominal surgery, or as a side effect of certain medications, then food can stay in the small intestine for too long. If your immune system is compromised, perhaps because of a viral infection, or an autoimmune disease, this can throw your microbiome off balance. It can also happen if you have a history of abdominal radiotherapy.
Not enough is currently known about SIBO and its causes. If you think you might be affected you should speak to your doctor or a registered dietician as soon as possible.
Do I have SIBO?
The symptoms of SIBO are usually nonspecific and overlap significantly with the symptoms of other gastrointestinal complaints, making it hard to diagnose. There are tests that can be done and treatments that can be prescribed; a change in diet is usually part of the picture.
If you have any persistent or unexplained gastrointestinal symptoms it is important that you speak to your doctor or a registered dietician so that they can help you identify and treat the underlying cause.
Can SIBO be treated? What do I do?
SIBO can be treated, but it should be diagnosed first. People with SIBO are typically given antibiotics to get on top of the bacterial overgrowth. A change of diet is also usually helpful to prevent it from recurring.
Some doctors ask their SIBO patients to follow what’s called an elemental diet, which means all liquids and no solids for several weeks. You should only follow an elemental diet with the assistance of a qualified dietitian, who will help you build up the volumes of liquid safely and help prevent you from losing weight.
With essential nutrients that are broken down for easier intestinal absorption, the blended liquid is either drunk or given through a feeding tube. It can restore bacteria balance in the microbiome, working very quickly in many cases. Some patients are unwilling to actually stay on it for as long as 2-3 weeks though because they find it too difficult to deal with.
Where can learn more about Small Intestine Bacterial Overgrowth?
Your doctor or registered dietician will be able to tell you more about SIBO and will be able to help you if you think you might be affected. You might also find the following websites helpful.
For that reason, most doctors don’t even suggest an elemental diet except in the most serious cases. It's much more likely that you will be recommended to follow the low-FODMAP diet. You can find out more about the diet and FODMAP compatible foods on our other pages.
Remember always to check with your doctor or a registered dietician before embarking on any major dietary change. This is to make sure that you have information that is accurate and appropriate to your needs.