Have you ever eaten something and within a few hours realized that your stomach is so bloated that you can’t button your pants? It’s not uncommon for my patients to tell me that they wake up with a flat belly and by the end of the day they look six months pregnant. Even if you haven’t experienced abdominal swelling to such an extreme, any amount of bloating is not normal; it’s a sign of intestinal inflammation. If you’re having gas or bloating regularly, or are dealing with IBS, there’s a strong likelihood you could have Small Intestinal Bacterial Overgrowth (SIBO).

What is SIBO?

As you might guess, Small Intestinal Bacterial Overgrowth, or SIBO, occurs when the bacteria in your small intestine get out of balance and overgrow.

The bacteria in your GI tract, which make up your gut microbiome, play a vital role in your immune system, thyroid function, bone health, and overall health. In fact, scientists have discovered that the gut microbiome contains tens of trillions of microorganisms, including up to 1,000 different species of bacteria with over 3 million genes — that’s 150 times more genes than human genes!

However, most of your gut bacteria is meant to be located in your large intestine and colon, where they help to break down food, synthesize vitamins, and eliminate waste. When these “healthy” bacteria that are normally found in the large intestine and colon colonize the small intestine, SIBO occurs.1SIBO can also be caused by an overgrowth of otherwise normal bacteria in the small intestine itself. As I always say, “Too much of a good thing can be a bad thing,” and this is true of SIBO.

The excess bacteria then feed off of the undigested food in your small intestine. In particular, they love to feed on sugar, simple and complex carbohydrates, starches, and alcohol – they’re real carb fiends!

As the bacteria feeds, it causes the carbohydrates to ferment, which produces hydrogen as a byproduct. Hydrogen can in turn feed single-celled organisms in your small intestine called archaea, which then produce methane as a byproduct. So when you have SIBO you have excess levels or hydrogen, methane, or both in your digestive system.

Carbohydrates feed SIBO → SIBO produces hydrogen → hydrogen feeds archaea → archaea produces methane

Depending on which gas is most predominantly produced, you can develop different symptoms and respond better to different treatments. Hydrogen-dominant SIBO typically leads to diarrhea, whereas methane-dominant SIBO is usually associated with constipation. I go into more detail on the two types of SIBO later.

The effect of all of this excess gas in your GI tract is what you might imagine. It leads to belching, flatulence, and can cause severe bloating. In fact, many people with SIBO report feeling as if they are 6 months pregnant by the end of the day!

Fortunately, once you get the bacteria under control and restore your gut’s natural balance, you can eliminate these frustrating digestive symptoms.

However, it’s not just digestive issues. SIBO can lead to a wide-ranging array of symptoms, including:

10 Signs You Have SIBO

1. Gas, bloating, and diarrhea
2. Abdominal pain or cramping
3. Constipation (much less common than diarrhea)
4. Diagnosis of irritable bowel syndrome (IBS) or inflammatory bowel disease (IBD)
5. Food intolerances such as gluten, casein, lactose, fructose, and particularly histamine intolerance
6. Chronic illnesses such as fibromyalgia, chronic fatigue syndrome, diabetes, neuromuscular disorders and autoimmune diseases
7. Vitamin and mineral deficiencies, including vitamins A, B12, D, and E
8. Fat malabsorption (signified by pale, bulky, and malodorous stools)
9. Rosacea and other skin rashes
10. Leaky gut

Because of the many ways its symptoms manifest in different people–sometimes showing no physical signs whatsoever–SIBO often goes undiagnosed. In fact, an estimated 6-15% of healthy, asymptomatic people and roughly 80% of people with IBS are actually suffering from SIBO.2

What causes the bacterial overgrowth?

Our gut relies on nerves, muscles, enzymes, and neurotransmitters to properly digest food. While enzymes mainly break down our food, the nerves, muscles and neurotransmitters physically move the food through our digestive tract from the stomach to the small intestine and to the colon. When this happens in a healthy gut, bacteria gets passed through the digestive tract along with the food to its final destination in the colon. Problems arise when something interferes with this process.

Damage to the nerves or muscles in the gut can result in leftover bacteria in the small intestine, increasing your risk for SIBO. 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, can also cause an abnormal buildup of bacteria in the small intestine. Diverticuli, which are tiny pouches that can form in the wall of the small intestine, can also collect bacteria instead of passing it on to the colon, where it belongs.

There are also medications that influence or disrupt the normal gut flora, such as antibiotics, acid-blocking drugs, and steroids. And of course, as I mentioned above, the most common cause for SIBO I see in my patients is from a diet high in sugar, refined carbohydrates and alcohol.

How to Test for SIBO

Before I explain which types of lab tests for SIBO are most effective and accurate, let’s recap the two different types of SIBO so that you can understand their role in testing.

Hydrogen vs Methane SIBO

As I explained earlier, when you have an overgrowth of bacteria in your small intestine, the carbs you eat are able to ferment before they can be broken down. This fermentation process releases hydrogen as a byproduct, so people with SIBO have elevated levels of hydrogen in their GI tract. This is why one of the most effective methods for diagnosing SIBO is to test the levels of hydrogen in your gut using a breath test.

However, you’ll remember that SIBO can also cause an increase in methane levels because the hydrogen feeds single-cell organisms in your gut called archaea, which produce methane. This can actually help reduce your hydrogen levels, and explains why you can have a false negative hydrogen test result and yet still have SIBO.

Studies have shown that high methane production is associated with constipation, and that patients who were treated for a bacterial overgrowth saw an improvement in their bowel regularity.3 So if you have SIBO and are dealing with constipation (which is less common), you likely have methane-producing SIBO.

Methanogens also lead to increased production and absorption of short-chain fatty acids, and have been linked to higher rates of obesity. In fact, one study found that people with higher intestinal methane production had higher BMIs.4

The reason this is so important is that you ideally want your lab testing to identify which type of SIBO you have, because they respond differently to different treatment options.

Lab Testing Options

1. Breath Test

This is by far the gold standard when it comes to SIBO lab testing because it is the most accurate and also determines if your SIBO is hydrogen or methane dominant. However, it can be a bit cumbersome.

You’ll need to fast for 12 hours, and breathe into a small balloon to measure your baseline levels of hydrogen and methane. Then you’ll ingest a precise amount of sugar (which feeds the bacteria) and repeat breath samples every 15 minutes for 3 or more hours to see if your levels of hydrogen or methane increase.

If your hydrogen levels are high then you likely have hydrogen-dominant SIBO, and vise versa. 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 lab tests the 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 one single urine specimen. However, it doesn’t determine whether your SIBO is hydrogen or methane-dominant.

3. Comprehensive Stool Test

This is also a functional medicine lab test looking at the flora of the large intestines. If I see all elevated levels of good bacteria, I suspect SIBO. Because my patients are typically dealing with multiple, overlapping gut issues such as Candida overgrowth, SIBO, and parasites, I often use stool testing so that we can test for multiple gut infections at one time.

4. Symptoms Checklist

Using the list of symptoms above and looking at a patient’s health history to see if the lifestyle factors associated with SIBO are present, I am often able to make a diagnosis simply by listening to the patient.

3-Step Protocol for Treating SIBO

Treating SIBO is a 3-step approach that works to eliminate the overgrowth and restore your gut’s natural balance on 3 fronts.

Step 1: Starve the Overgrown Bacteria

The first step is to remove the foods that feed the bacteria in your small intestine, including sugar, alcohol, and carbohydrates. This includes the usual suspects, such as bread, cookies, cake, and cocktails, as well as complex carbohydrates such as whole grains and legumes. Ultimately these foods are broken down into sugar in your gut, which feed the bacteria.
During this time you’ll eat plenty of non-starchy vegetables, leafy greens, lean proteins, and healthy fats, with minimal fruit.

Step 2: Attack the Bacteria

In my clinic I typically use the antibiotics Xifaxan and Neomyacin to attack the bad bacteria, depending on which gas is more dominant. Xifaxan is more effective with hydrogen-dominant SIBO and Neomyacin tends to be more successful with methane-dominant SIBO. These antibiotics work exceptionally well to kill the pathogenic bacteria with the least amount of disruption to the good bacteria in your microbiome.

If you are treating your SIBO at home, as thousands have done successfully, the protocol is to use Microb Clear™, which is a blend of magnesium caprylate, berberine, and extracts from tribulus, sweet wormwood, grapefruit, barberry, bearberry, and black walnut. These ingredients work to kill off the bacteria naturally.

While they aren’t specific to pathogenic bacteria and can disrupt your good bacteria, they aren’t as harsh as broad spectrum prescription antibiotics, which are like a bomb that wipes out good bacteria and bad bacteria alike. Microb Clear™ is much more natural and gentle. You can think of its effect more like pruning, rather than a bomb.

Step 3: Restore Your Good Bacteria

The final step is to restore the good bacteria in your gut to support a strong immune system and optimal digestion and nutrient absorption. However, when it comes to SIBO you want to be particularly careful because certain probiotics can actually add more fuel to the fire.

The Problem with Most Probiotics

When you have an overgrowth of bad bacteria in your small intestine, the bacteria are often of the lactobacillus or bifidobacterium species. And since the majority of probiotic supplements out there contain lactobacillus or bifidobacterium, using this type of probiotic is adding to the bacteria in your small intestine and throwing fuel on the fire.

In fact, one clue that you may have SIBO is that when you take a probiotic containing lactobacillus or bifidobacterium you have an exacerbation of your symptoms such as more gas, bloating, constipation, diarrhea or other digestive symptoms.

Why Soil-Based Probiotics Are Best for SIBO

Soil-based probiotics, such as my Primal Earth™ Probiotic, will not exacerbate your symptoms or add fuel to the fire because they don’t colonize the small intestine or feed the bacteria already growing there, since they don’t contain lactobacillus or bifidobacterium strains, yet they still provide all the benefits of a probiotic.

Soil-based probiotics also have a seed-like structure that protects them from stomach acid, bile salts, and digestive enzymes so that the bacterial strains remain alive. They can actually sense when the environment is safe for them to emerge and begin colonizing your large intestine and colon. This makes them a great option for SIBO because they don’t populate the small intestine and contribute to bacterial overgrowth there, instead heading straight to the large intestine and colon where they can support vibrant health.

Amy Myers MD, “10 Signs You Have Small Intestinal Bacterial Overgrowth (SIBO) , Amy Myers MD  amymyersmd.com

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