functional nutrition

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

(602) 422-9800

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

SIBO Is Sneaky. Let’s Look at Who Might Have It

Share This Post!

Woman in her pajamas is laying down with her hands on her stomach because she has belly pain from SIBO.

Table of Contents

This month we’re taking all things SIBO — small intestinal bacterial overgrowth. SIBO is Irritable Bowel Syndrome’s sneaky cousin. Many people who suffer with IBS also have this overgrowth of bacteria lurking in their small intestine.

Last week we had an overview of SIBO. This week we’re going to dig in and talk about the causes of SIBO.

Why is bacteria good for your large intestine and bad for your small intestine?

Your microbiome — the colony of bacteria that lives in your large intestine — does wonders for your health. It boosts your immune system, helps out your digestion, and supports your mood and brain health.

Your large intestine is the perfect spot for the growth and survival of bacteria because it has a stable pH, which allows for a wide range of bacterial species to thrive. And by the time what’s left of your dinner reaches the large intestine, you’ve already extracted most of the nutrients you need from it. And what’s left makes great food for the healthy bacteria that live there. Plus, the large intestine has a generous mucosal layer that protects your tissues and helps keep things in balance.

But when bacteria migrate to the small intestine and multiply, it doesn’t work out so well. The small intestine — which is normally relatively low in bacteria — isn’t equipped to handle a large population. First off, the bacteria may compete with your body for nutrients. And when it grows there, it produces gasses and other byproducts that can cause bloating, belly pain, and diarrhea.

Because the small intestine isn’t coated with thick mucus like the large intestine, SIBO can damage the lining of the small intestine, leading to inflammation and other digestive problems. And since the bacteria is competing with your intestines for the absorbable nutrients, SIBO can cause nutrient deficiencies and other health problems.

What are the causes of SIBO?

Like most complex health conditions, there isn’t one single cause for SIBO. It’s not like you get exposed to SIBO like you would a cold. An overgrowth of bacteria in your small intestine can come from a variety of factors. Generally, it means that something is out of balance in your digestive system.

But if you have SIBO, it’s a good idea to work with a practitioner who has the experience to figure out what caused your individual case of SIBO. This way you can address the underlying issue and not only stop the overgrowth, but prevent it from happening again.

Here are a few potential causes of SIBO your practitioner may consider:

Small intestine pH levels

Remember high school chemistry class? You probably learned about the pH scale that measures whether a substance is an acid or a base. A lower pH means that something is more acidic, and a higher pH means it’s more alkaline.

Your body cares a lot about pH, especially when it comes to digestion. The small intestine is a relatively low pH environment. And this helps keep bacteria from taking hold and colonizing the area. But if the pH of the small intestine is too high, it’s easier for bacteria to grow.

Your small intestine pH levels can be thrown off by disruptions in your digestion. If you have low levels of stomach acid or your food moves too slowly through your intestines, bacteria can take hold. Certain medications, chronic stress, or underlying medical conditions can also cause your pH to become more alkaline, creating an environment that can lead to SIBO.

Physical Abnormalities

It’s possible that you’re more susceptible to SIBO because of the way your small intestine is shaped. A narrowing of the small intestine can slow down transit time, allowing bacteria to grow. Or scar tissue from surgery or inflammation can change the anatomy of the small intestine and slow down transit time as well.

Inefficient Muscle Movement

If the muscles in your small intestine are not working efficiently, sometimes it takes your food too long to move through to your large intestine. And anything that slows down this transit time can create an environment ripe for bacterial growth. Sometimes this is an immune system problem.

Immune System Issues

Your immune system is constantly working to maintain a bacterial balance in your body. Some bacteria are beneficial, while some aren’t. You want good bacteria in your large intestine, but you probably would rather avoid the bacteria that causes strep throat or a gut imbalance.

If your immune system is having trouble maintaining a healthy population of beneficial bacteria while suppressing the growth of harmful bacteria, then SIBO can develop.

If you have any of these conditions, you could have SIBO too:

Viral gastroenteritis — better known as a stomach bug

We’ve all had it: fever, vomiting, diarrhea. It’s not fun. Usually a common stomach bug only lasts 24 hours or so. But sometimes the after effects can last much longer. A stomach bug can throw off the balance of good and bad bacteria in your large intestine. And if this happens, the bad bacteria is more likely to work its way up into the small intestine and cause SIBO.

Celiac disease

Celiac disease is an autoimmune disorder that’s triggered by gluten — a protein found in wheat, barley, and rye. Over time, exposure to gluten can damage the lining of the small intestine, reducing the number of digestive enzymes and disrupting the normal digestive processes. And you guessed it, this damage creates an environment that can lead to SIBO.

Crohn’s disease

People with Crohn’s disease are susceptible to SIBO because of the chronic inflammation that occurs in the small intestine. This inflammation can damage the lining of the small intestine and disrupt digestion, creating an environment where bacteria can thrive. Crohn’s disease can also slow down your transit time. And antibiotic use to manage Crohn’s disease can disrupt the microbiome, leading to more bad bacteria.

Hypochlorhydria — low levels of stomach acid

Stomach acid is a vital component to digestion. If your levels are low (and for many people they are), it can affect both the pH of your small intestine and how well your food is digested before it gets there. It’s important that the food in your stomach is broken down and that the pH is low enough to keep everything working smoothly.

Irritable Bowel Syndrome (IBS)

When you think of IBS, you’re probably concerned about your large intestine. But in reality, this issue affects your entire digestive system. IBS can impact both your immune function and your transit time.

In fact, most people who have IBS also have SIBO. Studies have shown that the number is probably somewhere in the 80% range. And I’ve seen that play out in my practice as well. I almost always test my IBS patients for SIBO. We’ll dig deeper into the IBS/SIBO connection next week.

But wait, there’s more…

Yes, there are more risk factors for SIBO. Like I mentioned, SIBO is complex. And any complex illness also tends to have complex causes. So if you know (or suspect) that any of the following are a problem for you, it’s a good idea to talk with your practitioner about the possibility that you also have SIBO:

? Gastroparesis

? Nerve damage

? Cirrhosis

? Portal hypertension

? Certain gastric bypass procedures

? Surgeries that cause strictures or adhesions

? Diabetes

? Systemic Sclerosis (scleroderma)


? Parkinson’s disease

? Hypothyroidism

What do I do if I think I have SIBO?

If you have one of the above conditions or risk factors for SIBO, it’s a good idea to reach out to a good practitioner who can test you for it. Your regular doctor may not know much about SIBO. And sadly, many gastroenterologists are uniformed too.

But that’s why I’m here! Your doctor doesn’t necessarily have the time or the knowledge to help you with complex digestive issues like IBS or SIBO. But I do. If you’d like to find out more, click the button below.

Free IBS Resource Guide
The Top 5 IBS Resources I Use Every Day
Get your Free Meal Picklist
Join My Free Facebook Group
Meet Alyssa
Alyssa Simpson RD, CDE, CLT
registered dietitian weight loss tips
Is IBS Slowing You Down?

Get Your Free IBS Resource Guide Now and start feeling better fast!