SIBO Symptoms, Causes, Testing & Diagnosis

Have you ever experienced bloating so bad that you can’t button your pants? If you experience gas or bloating regularly or have been diagnosed with IBS, there’s a strong likelihood you may have small intestinal bacterial overgrowth (SIBO). Even if you don’t experience symptoms like abdominal swelling to an extreme, any amount of bloating is not normal. Bloating is a sign of intestinal inflammation, which is one of the more common SIBO symptoms.

Before we get to the step-by-step process to help eliminate SIBO, it’s important to know how to spot and identify symptoms.

What is SIBO?

SIBO, also known as Small Intestinal Bacterial Overgrowth is basically what the name describes. The bacteria in your small intestine get unbalanced and overgrow, instead of living in a balanced state.  

In fact, I like to think of your microbiome as a rainforest, with many different species living together in harmony. Together, these species play a vital role in your immune system, thyroid function, bone health, and overall health. 

Most of your gut bacteria are meant to be in your large intestine and colon. Here they help break down food, synthesize vitamins, and eliminate waste. However, medications or a poor diet can cause your rainforest to become unbalanced. When this happens, the bacteria normally found in the large intestine and colon overgrow and colonize in your small intestine — leading to SIBO symptoms. What’s more, your gut is naturally lined with mucus that lubricates and protects it. However, an overgrowth of intestinal bacteria can damage your gut’s mucosal lining. Damaged mucus creates an opportunity for bacterial biofilms — or groups of microorganisms that are protected by a layer of protective slime — to attach to your cell wall, making them harder to control.

9 SIBO Symptoms

As I always say: “too much of a good thing can be a bad thing,”. This is true when it comes to small intestinal bacterial overgrowth. Too much good or bad bacterial flora in the small intestine produces a number of gastrointestinal symptoms that interfere with your normal digestive process. SIBO symptoms can range from digestive imbalance to chronic illness and autoimmune conditions. Here are the main symptoms you might experience:

Gas, Bloating, and Diarrhea

Once in the small intestine, the bacteria feed on undigested food and produce either methane or hydrogen, depending on which type of bacteria overgrows. I’ll discuss hydrogen vs methane more in a bit.

Abdominal Pain

Small intestinal bacterial overgrowth causes inflammation in your digestive tract, which can lead to painful symptoms such as abdominal pain and cramping,

Constipation (Much Less Common than Diarrhea)

SIBO can disrupt the natural gut flora, which affects your ability to eliminate waste and lead to constipation.

Irritable Bowel Syndrome (IBS) or Inflammatory Bowel Disease (IBD)

SIBO symptoms are extremely similar to those of IBS. In fact, one study proved that nearly 80% of people with IBS also had SIBO. When the SIBO was treated, nearly half of the patients experienced an improvement in their IBS. 

Food Intolerances

Intolerances such as gluten, casein, lactose, fructose, and particularly histamine intolerance: SIBO causes dysmotility, which inhibits your ability to properly digest foods and allows both food and bacteria to sit in your digestive system for longer, further exacerbating inflammation. 

Leaky gut: inflammation in your gut leads to intestinal permeability, where the tight junctions holding your intestinal wall together become loose. When you have leaky gut, toxins, microbes, and undigested food particles can escape through the holes and into your bloodstream, where your immune system marks them as pathogens and attacks them.

Chronic Illnesses

Illnesses such as fibromyalgia, chronic fatigue syndrome, diabetes, neuromuscular disorders, and autoimmune diseases: as your gut remains leaky and more and more particles escape into your bloodstream, your immune system sends out wave after wave of inflammation. Eventually, it becomes over-stressed and begins firing less accurately. What’s more, many particles that are now flooding your bloodstream look like your body’s own tissues. Your immune system creates antibodies against these substances, which mistakenly attack your tissues in a phenomenon called molecular mimicry.

Vitamin and Mineral Deficiencies

Deficiencies, including vitamins A, B12, D, and E: when your gut lining is impaired, your ability to absorb nutrients is impacted. So even if you’re getting plenty of vitamins and minerals in your diet, they might be passing straight through your body without providing any benefits and creating nutritional deficiencies.

Fat Malabsorption

When you have SIBO, the bile acids responsible for the breakdown and absorption of fat are deficient, resulting in a pale-colored stool that is also bulky and malodorous. 

Rosacea and Other Skin Rashes

Rosacea and other skin rashes: Small intestinal bacterial overgrowth damages the gut lining, which leads to the release of cytokines (regulators of host immune responses that promote inflammatory reactions) resulting in skin inflammation.

What Causes SIBO?

After enzymes break down our food, it travels through our digestive system from the stomach to the small intestine. In a healthy gut, bacteria gets passed through the digestive tract along with our food to the colon. Unfortunately, this process can be disrupted by a number of risk factors, including:¹

• Damaged nerves or muscles in the gut resulting in leftover bacteria in the small intestine. For example, diabetes mellitus and scleroderma can both affect the muscles in the gut, leaving room for SIBO to develop.
• Physical obstructions in the gut, such as scarring from surgeries or Crohn’s disease and diverticula (tiny pouches that can form in the wall of the small intestine) can collect bacteria instead of passing it on to the colon, where it belongs.
• Medications that influence or disrupt the normal gut flora including antibiotics, acid-blocking drugs, and steroids. 
• A diet high in sugar, refined carbohydrates, alcohol, and other high-carb foods you eat or drink.

How SIBO Produces Hydrogen & Methane Gas

While colonizing in your small intestine, the group of overgrown bacteria can thrive by feeding off the undigested food passing through. This process of fermenting carbohydrates produces hydrogen. Hydrogen can feed the single-celled organisms in your small intestine called archaea, which then produces methane. All that excess gas in your gastrointestinal tract is what contributes to the severe bloating people experience while dealing with SIBO, in addition to a whole host of digestive, mood, and chronic issues.

Do You Have SIBO Symptoms, or IBS?

Because of the many ways in which SIBO symptoms manifest in different people — sometimes showing no physical signs whatsoever — these symptoms often go undiagnosed. An estimated 6-15% of healthy, asymptomatic people, and roughly 80% of people with IBS, actually suffer from small intestinal bacterial overgrowth.²

SIBO Testing

Before I explain the most effective and accurate lab tests for SIBO³, let’s recap the two different types of small intestinal bacterial overgrowth so that you can understand their role in testing.

Hydrogen vs Methane

As I explained earlier, when you have an overgrowth of bacteria in your small intestine, the carbs you eat can ferment before they are broken down. This fermentation process releases hydrogen gas, so people who experience SIBO symptoms often exhibit elevated levels of hydrogen in their GI tract. 

Hydrogen SIBO

Hydrogen dominant or hydrogen SIBO is diagnosed by a sufficient rise in hydrogen on a breath test. This form of bacterial overgrowth is also referred to as diarrhea-prone SIBO, as the by-products of carbohydrate fermentation create an osmosis-like effect, drawing water into the bowel and causing diarrhea. 

What’s more, hydrogen SIBO can cause damage to your gut’s mucosal lining, creating a lactase deficiency. Lactase is the enzyme we use to break down and digest lactose. This is another reason why sudden food intolerances are a sign of an underlying gut infection.

Methane SIBO

SIBO can also cause an increase in methane levels. As the hydrogen feeds single-cell organisms in your gut called archaea, they produce methane. This can reduce your hydrogen levels which explains why you can have a false negative hydrogen breath test result and still have methane SIBO.

If you have small intestinal bacterial overgrowth and are dealing with constipation as your main symptom, you likely have methane SIBO.

You ideally want your lab testing to identify which type (hydrogen or methane SIBO) you have as the two respond differently to different treatment options.

SIBO Lab Testing Options

1. Breath Test

This is certainly the gold standard when it comes to a SIBO test. It is the most accurate and determines if the bacterial overgrowth is hydrogen or methane dominant. However, it can be a bit cumbersome.

For this test, you need to fast for 12 hours and breathe into a small balloon to measure baseline levels of hydrogen and methane. Then, you ingest a precise amount of sugar to feed the bacteria and repeat breath samples every 15 minutes for 3 or more hours to see if levels of hydrogen or methane increase.

If your hydrogen levels are high then you likely have hydrogen SIBO. However, just because one gas is dominant doesn’t mean that only one type of gas is present. You can have both types of gas present, one is just more prevalent.

I recommend the Lactulose Breath Test from Aerodiagnostics.

2. Organix Dysbiosis Test

This functional medicine SIBO test runs urine for by-products of yeast or bacteria in the small intestine. If your small intestine is housing a yeast or bacterial overgrowth, byproducts will appear in your urine, indicating their presence. This test is much easier for patients and only requires a single urine specimen. Yet, it does not determine whether your bacterial overgrowth is hydrogen or methane-dominant.

3. Comprehensive Stool Test

This is also a functional medicine test looking at the flora of the large intestines. If I see elevated levels of all good bacteria, I suspect SIBO. I often use stool testing to test for multiple gut infections at one time. This is because there were usually multiple, overlapping gut issues such as Candida overgrowth, small intestinal bacterial overgrowth, and parasites.

4. SIBO Symptoms Checklist

Using a patient’s health history, lifestyle factors, and the list of common symptoms above, I am often able to make a diagnosis by listening to the patient’s symptoms.

3-Step Protocol for Treating SIBO

Treating your bacterial overgrowth is a 3-step approach that works to eliminate the overgrowth and restore your gut’s natural balance. My SIBO Support Protocol is a step-by-step process to help you beat small intestinal bacterial overgrowth for good. In it, you find all the information you need to get control over the overgrowth. With the SIBO Support Protocol, not only do you get information, supplements, and a solution, you also get the support you need to take on these three steps. 

Step 1: Starve the Overgrown Bacteria

Starve the overgrown bacteria by removing the foods that feed it from your diet. This means cutting all sugar and alcohol and limiting carbohydrates such as fruit, starchy vegetables, grains, and legumes. 

While some inflammatory foods can be reintroduced after getting your gut back in balance, I recommend a SIBO diet that ditches gluten and dairy for good, particularly if you have an autoimmune or thyroid condition.

Step 2: Attack the Bacteria

In my clinic, I typically used the antibiotics Xifaxan and Neomycin to attack the bad bacteria. Xifaxan is more effective with hydrogen-dominant SIBO and Neomycin with methane SIBO. These antibiotics kill the pathogenic bacteria with the least amount of disruption to the good bacteria in your microbiome.

If starving the overgrowth and attacking the bacteria have little effect on your SIBO symptoms, it could be because a biofilm has formed around the overgrown bacteria, making it more difficult to eliminate. In these cases, I recommend treating bacterial overgrowth with a biofilm disruptor such as Microb-Clear®. It is a blend of magnesium caprylate, berberine, and extracts from tribulus, sweet wormwood, barberry, bearberry, and black walnut. These ingredients work to kill off the bacteria naturally.

The ingredients are not as harsh as broad-spectrum prescription antibiotics which can wipe out good and bad bacteria alike. Microb-Clear® is a natural and gentle way to support your journey to optimal health.

Step 3: Restore Your Good Bacteria

The final step is to restore the good bacteria in your gut. This will help support a strong immune system, optimal digestion, and nutrient absorption. Moreover, when it comes to small intestinal bacterial overgrowth you want to be particularly careful. Certain probiotics can add fuel to the fire and exacerbate your SIBO symptoms.

The Problem with Most Probiotics

When you have an overgrowth of bacteria in your small intestine, it is often lactobacillus or bifidobacterium species. The majority of probiotic supplements contain these species, so using them adds to the bacteria in your small intestine. 

Consequently, one clue that you may have small intestinal bacterial overgrowth is that probiotics containing lactobacillus or bifidobacterium exacerbate your symptoms.

Why Soil-Based Probiotics Are Best for SIBO

Soil-based probiotics don’t colonize the small intestine or feed the bacteria already growing there. In short, they do not contain lactobacillus or bifidobacterium strains, yet provide all the benefits of a probiotic.

These steps, supplements, and more can all be found in my SIBO Support Protocol.

Using this tried and true method, you can combat your symptoms of SIBO and take back your health in the long term!