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Sibo Doctor Approved
Alyssa Simpson RD, CDE, CLT
Alyssa Simpson

RDN, CGN, CLT
(602) 422-9800

Sibo Doctor Approved
certified gastrointestinal nutritionist
Sibo Doctor Approved
certified gastrointestinal nutritionist

Could I Have Both IBS and SIBO? Yes, Here’s Why

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Girl holding an interconnected metal brain teaser puzzle pieces to show the IBS/SIBO connection.

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If you suffer from Irritable Bowel Syndrome (IBS), you know what frustration feels like. Whether you’re dealing with abdominal pain, bloating, bowel movement issues or all of the above, IBS has likely impacted your quality of life.

But if you’ve been following along with me this month, you’ve been learning that IBS sometimes has a hidden partner in crime. Small Intestinal Bacterial Overgrowth (SIBO) is a condition that’s been gaining attention in recent years as a contributing factor — or even a cause of — IBS.

What is SIBO?

Trillions of microorganisms call your large intestine home. These microbes make up your microbiome, or gut bacteria. And they play a crucial role in maintaining gut health and overall well-being.

Generally, a large and healthy bacterial population in your large intestine is a good thing. But you don’t want them moving into your small intestine where they can cause problems. If you have SIBO, some of these microorganisms have wandered upstairs and started a party in the small intestine (where they’re just not welcome).

SIBO symptoms include bloating, abdominal pain, diarrhea, and constipation. Yes, these are often the exact same symptoms that show up with IBS.

What’s the Difference Between SIBO and IBS?

Let’s start with a definition of Irritable Bowel Syndrome, or IBS. Technically speaking, IBS is a collection of digestive symptoms that are unrelated to any structural abnormalities. IBS isn’t contagious. And it isn’t easily identified. You can’t just go to your doctor and request an IBS test because there simply isn’t one.

An IBS diagnosis is based mainly on your symptoms. Your practitioner will probably first rule out other serious issues like inflammatory bowel disease (IBD) or celiac disease, since those conditions share some of the same symptoms as IBS. And then she’ll look at your symptoms and overall experience and determine whether or not you have IBS.

IBS symptoms vary widely from person to person. But common issues include abdominal pain, bloating, bowel movement issues, and a feeling of incomplete bowel emptying.

IBS and SIBO are two different — but often related — conditions. Symptoms for both can vary from mild to severe. But the two conditions have much in common:

? Loss of appetite

? Abdominal pain

? Cramping

? Bloating

? Nausea

? Excess gas

? Alternating bouts of constipation and diarrhea.

Location. Location. Location. That’s the main difference between IBS and SIBO. IBS primarily impacts the large intestine, although your symptoms can appear in other areas of the digestive process. SIBO is specific to the small intestine. It’s also a lot simpler to test for SIBO. While an IBS diagnosis is a little more subjective, there are ways to know for certain if you have an overgrowth of bacteria in your small intestine.

Since the large and small intestines are next door neighbors in the digestive process, what happens to one can affect the other. So IBS and SIBO often go hand-in-hand.

The IBS/SIBO Connection

In my practice, I specialize in helping people with IBS and other digestive issues. And after helping over 1,000 patients, I’ve seen a strong connection between IBS and SIBO. In fact, when someone comes to me with IBS, I routinely test for SIBO too. More often than not, someone diagnosed with IBS also tests positive for SIBO.

And there’s all sorts of research that backs up what I’ve seen in my practice. IBS and SIBO have many common symptoms. And research suggests that SIBO could even be an underlying cause or a contributing factor of IBS. in fact, some studies report that up to 80% of IBS patients also have SIBO. So while it’s not everyone, a majority of people with IBS likely also have SIBO.

We don’t have exact answers on the IBS/SIBO connection, but there are several proposed theories. It’s possible that the overgrowth of bacteria in the small intestine disrupts the normal movement in the digestive tract that pushes food along. And this could lead to IBS symptoms. The overgrown bacteria may also trigger an immune response, causing inflammation and gut hypersensitivity — also common features of IBS.

The gut and brain are deeply interconnected. Did you know your gut makes some of your brain chemicals including serotonin and dopamine? This gut-brain connection may also play a role in the relationship between IBS and SIBO. The overgrown bacteria in the small intestine may affect the gut-brain axis and lead to IBS symptoms.

And some of the risk factors for SIBO — including impaired gut motility (how well your digestive system moves food through) and the use of certain medications — are also risk factors for IBS.

According to a 2018 research review, the precise connection between the two conditions is still a bit murky. Scientists have yet to figure out for sure whether SIBO is a cause or a consequence of IBS. Or it could be both.

There are several factors that can increase the likelihood of someone having both IBS and SIBO. These include:

✔ Being female

✔ Older age

✔ Bloating and flatulence being predominant symptoms

✔ Diarrhea subtype of IBS (IBS-D)

✔ Having fibromyalgia

What You Can Do if You Think You Have Both IBS and SIBO

SIBO and IBS share a complex, but common relationship. And while not all IBS patients have SIBO (and not all cases of SIBO are associated with IBS), they do show up together — A LOT.

If you have been diagnosed with IBS — especially if you’re still struggling with persistent symptoms — SIBO may be an issue for you. Working with a qualified healthcare professional (like me) can help you get to the bottom of what’s really going on with your digestive issues. I offer a consultation if you’d like to talk about what’s going on with your stomach issues.

In the meantime though, I’ve put together a resource you might find helpful for both IBS and SIBO. Click the button below to download my free IBS Resource Guide for some food, supplement, and app suggestions to help you on your journey.

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Alyssa Simpson RD, CDE, CLT
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