Bacteria inside of the gastrointestinal tract

What is SIBO – is it Real? Symptoms, Diagnosis and Treatment

If you have gut issues of any kind and have done any research on gut health, you have probably heard of the term SIBO (pronounced see-boh). This stands for Small Intestinal Bacterial Overgrowth and yes, it is a real thing.

Not only is it real, it is actually fairly prevalent among people with IBS but it does occur outside of IBS diagnoses as well.

What Actually is SIBO?

Contrary to popular belief, SIBO is NOT the presence or overgrowth of BAD bacteria. It is a displacement of our normal gut bacteria.

We all have bacteria living inside our GI tract… lots of it. And this is a good thing! These bacteria help us digest substances that are indigestible to humans like fiber. However, these bacteria live, for the most part, in our large intestine… at least they SHOULD.

SIBO occurs when our normal gut bacteria populate the small intestine. Our small intestine should have very few bacteria living there. When the small intestine, becomes populated with bacteria, however, an imbalance in the types of bacteria present also occurs which compounds the problem.

Our bacteria should be living in a pretty little harmony together in our GI tract. When this balance gets out of whack, so do we.

Woman making a heart shape with her hands over her abdomen.

So why is this a problem?

First off, much of the food that we eat should be broken down and absorbed by US. Whatever we do not or cannot use, is passed onto the large intestine to be digested by bacteria or excreted from our body. If bacteria are populating our small intestine in large numbers, THEY are digesting OUR food! How rude.

This may not seem like a big deal but it’s actually a huge deal and can result in malnutrition. Our body runs off of the nutrients we provide it through our diet. It needs these to function properly. We can also see negative outward effects of this malnutrition on our weight, skin, hair, etc.

Second of all, when bacteria digest nutrients in our body, the byproduct is gas production. Our large intestine is designed to handle this well. Our SMALL intestine is not. It is called “small” for a reason and has a smaller diameter than our large intestine. So a large amount of gas production in our small intestine can lead to distention, sensation of bloating, pain, etc.

Other Symptoms of SIBO

In addition to those listed above, other common symptoms of SIBO include the following.

  • Loose stool or diarrhea
  • Constipation (sometimes both diarrhea and constipation)
  • Excessive burping
  • Excessive flatulence
  • Bowel urgency
  • Brain fog
  • Fatigue
  • Nausea
  • Loss of appetite
  • Food sensitivities

These are some of the most common symptoms but SIBO can present differently between individuals.

How is SIBO Diagnosed?

SIBO can be diagnosed two ways. One way is to take a small bowel aspirate (sample of your small bowel “juice” if you will) during an esophagogastroduodenoscopy (EGD for short and means a scope of your upper GI tract under anesthesia).

The more common testing method, however, is a breath test. For this, you drink a sugar solution (either glucose or lactulose) and breathe into a sealed bag every 15-20 minutes for several hours. You then return these breath samples to a lab for analysis. Remember, bacteria produce gas when they digest food.

Therefore, if SIBO is present, there will be specific types of gas production occurring at specific intervals of time after consumption of the sugar solution. This is absorbed into your blood stream, carried to your lungs and expired on your breath. Yes this is real and yes this is a valid testing method, BUT not always 100% accurate. That said, these two tests are currently the best we have.

Outline shape of a gastrointestinal tract

Treatment for SIBO

Briefly, there are three treatments for SIBO.

  1. Pharmaceutical antibiotics
  2. Herbal antibiotics
  3. Elemental Diet – this is basically liquid nutrition that we absorb before it gets to the bacteria, essentially starving them.  

The treatment of SIBO deserves another post entirely. But for now, know that there are different types of SIBO (see my post “Types of SIBO”), and number 1 and 2 above can be tailored to treat the specific type appropriately.

Prevention of SIBO Relapse

One aspect of SIBO that is important to note, is that it is actually a symptom of something else. Meaning, there is always an underlying reason why it develops. This is important to pin point if possible, because in many cases, the underlying cause is chronic. If we can pin point the underlying cause and treat it, or at least help manage it, the risk of SIBO recurrence is lessened.


As prevalent as SIBO is, it can be easily overlooked. This may be a result of several factors. The research on SIBO is continually developing and some GI practitioners may not be familiar with the latest. Also, because SIBO symptoms are similar to symptoms of other GI ailments, it may not always be obvious that SIBO is present. Further, the presence of SIBO isn’t evident upon imaging or blood tests and these are often the first tests that are ordered by GI practitioners when presented with a new case.

Too many SIBO sufferers may unknowingly settle for an “IBS” diagnosis after multiple negative tests, imaging, etc. They may not realize there is actually something treatable going on in addition.

Mug of coffee next to a napkin that says trust your gut with a pen lying next to the napkin

One final word – if you suspect SIBO in either yourself or someone in your care, please know it is perfectly appropriate to ask for testing and to be your own advocate if needed!