SIBO vs. IMO what’s the difference and why it matters to YOU

2020 was the year EVERYTHING changed…

Yes, I’m talking about the shift from methane SIBO to IMO 😉

Jokes aside, for those of us dealing with Small Intestine Bacterial Overgrowth (SIBO), a lot has happened and changed in the past 2 years, and one the biggest changes was the shift from calling high methane gas SIBO, to calling it IMO – Intestinal Methanogen Overgrowth. 

Whether you’re nodding your head following along, or totally confused by what I just said: stick with me. In this post I will explain everything you need to know about the types of SIBO, IMO, and what the “name change” means for people with the condition. 

There Are 3 Types of SIBO

SIBO is a condition where bacteria overgrow in the small intestine. The overgrown bacteria consume carbohydrate-rich food and ferment those foods into gas. Different types of bacteria produce different gas.

Some bacteria consume carbohydrates and produce hydrogen gas. 

In hydrogen dominant SIBO, the most common symptom is diarrhea. 

Other bacteria – called Sulfate-Reducing Bacteria – consume carbohydrates and produce hydrogen sulfide gas. 

Hydrogen sulfide dominant SIBO is associated primarily with diarrhea, but also with constipation and a mixed bowel pattern. 

Finally, a third type of bacteria – or more specifically, another type of microorganism called archaea, consume carbohydrates and produce methane gas. 

Methane gas is associated with constipation. 

You may have high levels of just one gas type, 2 of the 3, or all 3. Traditional breath tests can reveal your methane and hydrogen gas levels. The new 3-gas Trio Smart breath test can reveal your levels of all 3 gases. 

Depending on what gas type is highest for you, your doctor may have told you have methane, hydrogen, or hydrogen sulfide type SIBO. 

Why Methane Is Different Than Hydrogen & Hydrogen Sulfide

What I just described  – the 3 types of SIBO – is what has been accepted and used by most doctors until very recently.

In 2020, Dr. Mark Pimentel, MD – the lead researcher in SIBO and IBS – suggested a change in name for methane SIBO for 2 big reasons:

First, the “bacteria” that cause methane gas are actually not bacteria – they are technically archaea, another type of microscopic organism that lives in the gut microbiome. If methane is caused by archaea, not bacteria, it makes the “B” in SIBO, which stands for bacteria, untrue.

Secondly, Dr. Pimentel’s new research has suggested that archaea causing methane gas may overgrow in the lower part of the digestive tract as well – the large intestine. That means that the overgrowth can be anywhere in the intestines, making the “SI” in SIBO, which stands for small intestine, not entirely accurate.

For these two reasons, Dr. Pimentel suggested a new name for methane SIBO: Intestinal Methanogen Overgrowth or IMO.

The Big Change: Methane SIBO is Now IMO

So that’s how we came to where we are now – with a new name for a condition that already existed. 

This shift has been understandably confusing for many people! It might make you question everything you know about your SIBO diagnosis. 

If you have methane-dominant SIBO – now called IMO – here’s what you need to know:

• The diagnostic criteria have not changed
• The symptoms and experience have not changed
• The proven treatments have not changed
• Your prognosis has not changed

Bottom line: the ONLY thing that has changed is the name!

If I Have IMO, Is SIBO SOS® Still For Me?

If you have previously has methane-dominant SIBO, and now have what is called IMO – you might be wondering:

Is SIBO SOS® still for me if I don’t technically have SIBO?

The answer is a big, fat YES!!!

From day 1, SIBO SOS® was created for people with all types of SIBO, IBS, and other functional gut disorders. 

While I won’t be changing the name of our site to “SIBO and IMO SOS” – because it just doesn’t sound as good – please know that EVERYONE is welcome here, and we will continue publishing valuable resources for people with all types of SIBO and IMO. 

The SIBO Recovery Roadmap®  – our flagship course for treating and beating SIBO – created by myself and SIBO expert Dr. Allison Siebecker has information for treating all 3 types of SIBO – and now, IMO. 

If you ever get confused by anything, please know that any time we say the words “methane SIBO” they mean EXACTLY the same as the word IMO or Intestinal Methanogen Overgrowth. 

And to help with the transition, we will use SIBO and IMO together whenever applicable.