Different Types of SIBO

by | Dec 5, 2023 | Blog, SIBO

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People who regularly suffer from symptoms like diarrhea or constipation may have SIBO. This condition is present in nearly 34% of people with digestive complaints who undergo a breath test.

SIBO symptoms can be uncomfortable at best and impact someone’s quality of life at worst. Combatting these effects begins with properly diagnosing the different types of SIBO.

We delve into this subject below, explaining each SIBO variant, its symptoms, treatments, and more.

What Are the 3 Different Types of SIBO?

The three different types of SIBO are hydrogen-dominant, methane-dominant, and hydrogen sulfide SIBO. They are named for the type of gas released by certain overgrown bacteria in the small intestine.

Each type of gas corresponds to a specific microbe or microbes. Detecting levels of these gasses can help healthcare providers identify which species contribute to the overgrowth and, therefore, someone’s SIBO symptoms.

Someone may have only one type of SIBO, but it is also possible to have two or more variants simultaneously. Discovering which type(s) contribute to the person’s symptoms can help providers develop a treatment plan.

Hydrogen-Dominant SIBO

Hydrogen is one of the most common gases produced by bacteria in the large intestine. This gas is created by hydrogen-producing bacteria. Firmicutes and Bacteroides account for 92% of the hydrogen released from the large intestine.

When hydrogen-producing Firmicutes and Bacteroides migrate into the small intestine, they can lead to hydrogen-dominant SIBO.

Other changes linked to hydrogen SIBO symptoms include the rise of serotonin and non-gaseous toxins produced by Firmicutes, Bacteroides, and other bacterial strains.

Bacteria in the gut synthesize about 90% of the body’s serotonin. Serotonin regulates mood and small intestinal contractions. SIBO compromises the latter function, leading to faster transit times of digested food through the bowels.

The non-gaseous toxins the small intestinal microbiome produces are also related to hydrogen SIBO symptoms. They can damage the intestinal lining (the cause of leaky gut syndrome), draw water into the bowels, and increase intestinal inflammation.

Hydrogen-Dominant SIBO Symptoms

The effects of bacterial overgrowth in the small intestine explain hydrogen SIBO symptoms. People with this type of SIBO frequently experience:

  • Diarrhea
  • Bloating
  • Stomach pain

Faster food transit times through the bowels lead to less nutrient and water extraction. Toxins that draw water into the bowels exacerbate the problem, leading to loose, watery stools- also known as diarrhea.

Untreated diarrhea comes with potentially life-threatening complications. Failure to extract water from digested food may lead to dehydration. Meanwhile, poor nutrient absorption can ultimately cause malnourishment.

Hydrogen SIBO Treatment

The antibiotic rifaximin is one of the most common treatments for hydrogen SIBO. Antibiotics kill off bacteria, including the strains in the small intestine that cause hydrogen SIBO symptoms.

Unfortunately, antibiotics do not work for everyone; overuse of antibiotics may even exacerbate symptoms. In these cases, herbal supplements like thyme and oregano oil, polyphenols, and berberines may be more beneficial for hydrogen SIBO.

People with hydrogen SIBO symptoms caused by a specific issue like low stomach acid will benefit more from addressing the underlying cause.

Hydrogen SIBO Diet

For those wanting a natural way to address SIBO symptoms, diet is key. Some diets can help manage symptoms. The Elemental Diet has been studied as a treatment for SIBO.

Diets that may help with symptom management include the low FODMAP diet, the specific carbohydrate diet, and the low fermentation diet. A gut health expert can help people find the most effective diet for their needs.

Foods to Avoid With Hydrogen SIBO

People with hydrogen SIBO should avoid foods known to contribute to hydrogen gas production. Carbohydrates are the most common source of hydrogen gas. Cutting out simple sugars, complex carbs, starches, and even some amounts of fiber may help alleviate symptoms.

Another strategy is to avoid foods that put stress on the digestive system. Deep-fried and other high-fat foods, processed foods, artificial sugar, citrus fruits, beans, cruciferous vegetables, dairy products, and spicy foods are hard on digestion.

Methane-Dominant SIBO

Methane-dominant SIBO is unique because bacteria do not cause it. Instead, the overgrowth of a type of methane-producing archaea known as methanogens leads to its symptoms.

Hydrogen and methane SIBO often occur together because methanogens require hydrogen gas to produce methane. When hydrogen gas increases in hydrogen-dominant SIBO, it can feed methanogens, leading to overgrowth.

Unfortunately, we do not know as much about this SIBO type as we do its hydrogen counterpart. Still, studies have uncovered a link between methane SIBO and conditions like anorexia and constipation-dominant irritable bowel syndrome (IBS-C).

Like methane SIBO, an overproduction of methane gas also plays a role in the development of IBS-C. SIBO and IBS, in general, are intimately connected. In this case, it is unclear whether SIBO causes IBS-C or vice versa, but they share similar symptoms.

Methane-Dominant SIBO Symptoms

The primary symptom of methane-dominant SIBO is constipation. People with methane and hydrogen SIBO may experience alternating bouts of constipation and diarrhea (more on the symptoms of methane and hydrogen SIBO in a bit).

One explanation for methane’s link to constipation again has to do with serotonin. Some studies have found that serotonin production declines with methane SIBO. The result is fewer bowel contractions, slower transit times, and constipation.

Two potential complications of methane SIBO are weight gain and increased body fat. These side effects come about due to the slower movement of digested food through the small and large intestines.

Recall that these organs extract nutrients from food. The longer food remains in transit, the more nutrients are absorbed into the body. Extracting more beneficial nutrients can be a positive thing, but when someone eats a calorically dense diet (e.g., one high in fats and sugars), the opposite is true.

Methane-Dominant SIBO Treatment

Methane-dominant SIBO can be tricky to treat. This SIBO type does not always respond to antibiotics since archaea, not bacteria, cause it. However, antibiotics like rifaximin may help starve off methane-producing archaea in cases where hydrogen SIBO causes methanogen overgrowth.

Natural remedies are the better way to approach methane SIBO. One study showed the benefits of probiotics containing Lactobacillus reuteri for methane SIBO symptoms, but the study was small.

Other options include supplements and dietary changes. Berberines, polyphenols, and herbaceous extracts are supplements to consider.

Methane-Dominant SIBO Diet

Methane-dominant SIBO diets aim to starve methanogens of their food of choice: hydrogen gas. As such, many of the same diets that work for hydrogen SIBO can also benefit this type. This includes the Elemental Diet, which has been studied as a treatment for methanogen overgrowth.

People with constipation from SIBO, IBS-C, or another cause can also treat their symptoms with increased fiber and water intake. High-fiber diets can make stools easier to pass. Fiber works in tandem with water to speed up transit times, which are slower in people with constipation.

Methane SIBO Foods to Avoid

The same foods that exacerbate hydrogen SIBO should be avoided by people with methane SIBO. Specifically, consider cutting out sources of carbs (e.g., sugars and starches) and constipation-causing foods like processed meats, baked goods, and cheese.

People trying diets to treat methane SIBO must be careful to consume enough nutrients. The body will increase methanogen production to extract nutrients from fiber if not enough calories are obtained through diet. This phenomenon explains why people with anorexia are more prone to methane SIBO.

hydrogen dominant sibo

Mixed-Type: Methane SIBO and Hydrogen SIBO Combined

Mixed SIBO is not listed as one of the different types of SIBO because it is not a distinct diagnosis. Instead, it occurs when people have the symptoms of methane and hydrogen SIBO: diarrhea and constipation.

For example, in a study of 1,461 people, more than 33% had SIBO. Of that group, nearly one in two had hydrogen SIBO, while 39% tested positive for methane SIBO. 11.4% received a diagnosis of mixed-type SIBO.

Hydrogen Sulfide SIBO

Hydrogen sulfide is the rarest and least understood type of SIBO. The diagnostic test for hydrogen sulfide SIBO only came out in 2020, and very little research has focused on this type.

What we do know is that hydrogen sulfide gas is associated with hydrogen sulfide SIBO symptoms. Hydrogen sulfide is an essential gas for the digestive system. It regulates gastrointestinal inflammation and helps repair damage to the intestinal lining.

The reason why hydrogen sulfide levels increase is less clear. It has something to do with an overgrowth of sulfate-reducing bacteria.

Hydrogen Sulfide SIBO Symptoms

Hydrogen sulfide SIBO does not just cause symptoms in the digestive tract. It can cause side effects throughout the entire body. When it does affect digestion, this type of SIBO typically causes:

  • Diarrhea
  • Stomach pain
  • Excessive and smelly gas

Some studies have found that hydrogen sulfide SIBO may cause constipation and bloating, too.

If left unchecked, sulfate-reducing bacterial overgrowth can damage the intestinal lining. Then, it may leak out into other areas of the body. High levels of hydrogen sulfide may potentially increase the risk of certain health symptoms and diseases.

Hydrogen Sulfide SIBO Treatment

A recent study investigated 131 people with hydrogen sulfide symptoms or positive breath test results. It found that low-sulfur diets and bismuth supplementation were significantly associated with a reduction in hydrogen sulfide SIBO symptoms.

Antibiotics may also reduce sulfate-reducing bacteria causing someone’s symptoms.

Hydrogen Sulfide SIBO Diet

As mentioned, low-sulfur diets may be beneficial for hydrogen sulfide SIBO symptoms. Gut bacteria must obtain sulfur from food sources to produce this gas. So, starving the body of sulfur will also kill off sulfate-reducing bacterial overgrowth.

Hydrogen Sulfide SIBO Foods to Avoid

People with hydrogen sulfide SIBO symptoms or diagnoses should avoid foods that are high in sulfur. These foods include but are not limited to:

  • Meat products
  • Fish and shellfish
  • Beans and legumes
  • Nuts and seeds
  • Eggs and cheese
  • Dried fruit
  • Cruciferous vegetables
  • Whole grains
  • Brassicaceae spices like horseradish and mustard

Tomato and grape juice, coconut milk, and fermented beverages like beer, cider, and wine are other high-sulfur products to avoid.

Whole-Body Interventions for SIBO

Lifestyle changes are excellent supplements to the diets and treatments we mentioned above. Here are three tips for optimizing treatments for the different types of SIBO.

Manage Stress

Stress is a common cause of digestive disorders, including SIBO. Stress leads to dysbiosis or an imbalance of microbes in the gut. Dysbiosis can increase the risk of SIBO or exacerbate someone’s pre-existing symptoms.

Prioritize Sleep

Poor quality or a low quantity of sleep puts more stress on the brain and body. As mentioned, stress can cause dysbiosis, a risk factor for SIBO. Additionally, sleep deprivation is associated with higher consumption of hard-to-digest foods, which can worsen SIBO symptoms.

Regulate Circadian Rhythms With Light

People who struggle with getting enough high-quality sleep may benefit from resetting their circadian rhythm. Exposure to bright lights, whether natural or artificial, can reset the circadian rhythm for more consistent and restorative sleep.

The Bottom Line

There are three different types of SIBO: hydrogen-dominant, methane-dominant, and hydrogen sulfur SIBO. Their symptoms and treatments differ, so getting the correct diagnosis is crucial.

Are you ready to discover your SIBO type(s) and the best treatments for your unique symptoms? Revolution Gut Health is one of the few providers specializing in SIBO diagnosis and treatment.

Schedule a consultation with our gut health experts for a customized treatment plan tailored to your unique SIBO type(s).


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