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This or That: Is it IBS or SIBO?

Have you ever been so bloated you look and feel 6 months pregnant? you have chronic constipation that just won't seem to go away?

Bloating, chronic constipation or diarrhea, flatulence, or maybe even abdominal pain are all common signs of irritable bowel syndrome (IBS). If you've received an IBS diagnosis or think your symptoms may be IBS, you might be curious about what that actually means. Keep reading to find out more about IBS and its relationship to SIBO.

So...what exactly is IBS?

IBS is a gastrointestinal disorder associated with uncomfortable symptoms like chronic constipation, diarrhea, flatulence, bloating, and even abdominal pain. It has no known cause, yet it is one of the most common gastrointestinal issues out there – with up to 45 million people in the US struggling with IBS. Because it has no known “official” cause, treatments can vary not only in type but also in success. From restrictive diets to medications and frequent doctors' appointments, people with IBS can often feel like there’s no solution to their symptoms. To worsen matters, an IBS diagnosis doesn’t actually pinpoint the cause of the symptoms - instead, it just refers to the symptoms experienced...thus making successful treatments harder to come by.

If this sounds like you, you’re not alone. My job as a functional dietitian is to get to the root cause of your symptoms so you can find real relief, not just a “band-aid” in the form of a pill. Overgrowth and imbalance of the bacteria in your intestines is one of the most overlooked root causes of IBS and is something that needs to be considered when addressing your symptoms.

Okay, then what about SIBO?

So, what’s causing your IBS? Well, it could be small intestinal bacterial overgrowth (SIBO). A recent study has shown that nearly 80% of people with IBS also have SIBO. Normally, your large intestine houses a large amount of bacteria that aid in digestion and normal gastrointestinal function. However, sometimes these bacteria can move into the small intestine and grow, which can cause the symptoms associated with IBS.

Simply put, SIBO is having too many bacteria in the small intestine, specifically bad bacteria that takes over and wreaks havoc. But why does this happen? And more importantly, what can you do about it?

SIBO Symptoms

First, let’s get into some of the most common symptoms you might experience if you have SIBO. Symptoms of SIBO can range from digestive imbalance to chronic illness and autoimmune conditions.

  • Gas, Bloating, Diarrhea, Constipation, Abdominal pain

These are symptoms common with IBS and SIBO. These symptoms can stem from the overgrowth of bacteria in the small intestine that actually produce gasses discussed a little bit later in the blog post.

  • Food Sensitivities:

The thing with SIBO is that it inhibits a person's ability to digest foods by interfering with digestive enzymes, stomach acid and bile secretion, contributing to impaired motility. It does this by damaging the lining of the small intestine (aka leaky gut), allowing food particles to enter the bloodstream and therefore, activating an immune response. Common food sensitivities associated with SIBO include dairy, gluten, and histamine. Food sensitivities are delayed immune reactions and can occur up to 72 hours after a food is consumed, so you might not associate a particular food with your symptoms, but in reality, it may be causing many issues.

  • Chronic illness

The immune system is responsible for regulating inflammation. Unfortunately, because SIBO impairs the lining of the gut, particles from the gut escape into the bloodstream and can cause systemic inflammation. This increase in inflammation is the root of many autoimmune conditions. Leaky gut is a contributing factor to autoimmunity, which happens when the immune system starts to attack the body instead of foreign invaders. When large proteins get into our body that should not be there, it can cause immune dysregulation. If certain genes are present for an autoimmune condition, it can create just the right environment for that autoimmune condition to become symptomatic.

  • Vitamin and mineral deficiency

Due to the gut lining being impaired, its ability to absorb nutrients is also impaired. So even if you're consuming enough nutrients through the diet, it may not translate to being absorbed by the body. This is important to address to prevent and fix nutrient deficiencies.

Root Cause of SIBO

There are many causes of SIBO. Listed below are some of the most common causes of SIBO. Women and people under 50 are at greater risk of developing SIBO.

  • Low stomach acid

    • Low stomach acid can occur in people who take proton-pump inhibitors (think omeprazole or Prilosec), have an H.Pylori infection, or have had gastric bypass surgery.

  • People who have taken a lot of antibiotics

  • Gallbladder removal

  • Food poisoning

  • Chronic constipation

  • Impaired motility and digestion

  • Structural problems in the small intestine

Regardless of the cause, it is important to know the different types of SIBO because these can influence the best course of treatment.

What Are The Different Types of SIBO?

1. Hydrogen SIBO: This is the most common type of SIBO in which the bacteria produce large amounts of hydrogen gas. It is usually characterized by bloating and increased gut transit time, leading to diarrhea.

2. Methane SIBO: This is the second most common type of SIBO where the bacteria produce methane gas. People with this kind of SIBO usually have constipation and may even experience weight gain. It’s often seen at the same time as hydrogen SIBO.

3. Hydrogen sulfide SIBO: Hydrogen sulfide gas is naturally produced by the body, but overgrowth of bacteria can produce it in excess. When this happens, it can c contribute to symptoms of leaky gut – inflammation and poor immune system function. It’s characterized by gas smelling like rotten eggs, abdominal pain, and food sensitivities.

Testing for SIBO

How do you know which type of SIBO bacteria you have?

There are a few different tests on the market that a functional provider can provide to get a more accurate picture of the type of SIBO you may be dealing with:

  • Breath test: This is the most common method. The breath test measures the type and amount of gas produced by the bacteria in your gut. This is a simple and noninvasive test. Most companies only test hydrogen and methane gas. Trio-smart breath test is the only one that measures all 3 gases.

  • Organix dysbiosis test: Organix is a urine test that measures organic acids. If your intestines are housing a bacterial overgrowth, by-products will reveal themselves in the urine sample.

  • Comprehensive stool test: Stool tests can reveal bacterial changes in the large intestine as well as fat malabsorption. Although a stool test is not typically used to diagnose SIBO, it can be helpful to see if SIBO is influencing digestion.

  • SIBO symptoms checklist: Although symptoms alone cannot diagnose SIBO, they can be a really good indicator. Each type of gas will produce different symptoms when overgrowth occurs. For example, methane gas is associated with constipation, whereas hydrogen gas is associated with diarrhea. If you complete a SIBO checklist and your test score is high AND you feel better on a low FODMAP diet, then you likely have SIBO.

Once you figure out what type of SIBO you have, then your provider can determine the best course of treatment for you.

Treatment of SIBO

There are a number of different areas that have to be addressed when treating SIBO.

  • Starve the overgrowth

  • Attack the bad bacteria

  • Restore the good bacteria

To accomplish this, you may be placed on antibiotics as well as vitamins and minerals to restore nutrient deficiencies.

Additionally, to prevent SIBO from recurring, the root cause has to be treated. In order to treat the root cause, additional testing may be required based on the recommendation of your functional provider.

A Note From Heather

If you have suffered from any of the issues listed above or have gotten a diagnosis of IBS but are still feeling sick, you know how discouraging and tricky treating this condition can be. Working with a functional dietitian can help you discover the root cause of your IBS in order to ultimately relieve your symptoms and restore your health. Reach out to me at or text me at 978-494-0110.

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