SIBO:
4 Different types & How we test for them

Small Intestinal Bacterial Overgrowth (SIBO) is a condition where excessive bacteria grow in the small intestine, leading to various digestive symptoms. There are four main types, each characterized by different bacterial profiles and symptoms. Let’s break down the types and their causes, and then look at how we test for them in functional medicine. 

1. Hydrogen-Dominant SIBO

• Characteristics:
  Hydrogen-dominant SIBO is the most common form and occurs when certain bacteria in the small intestine produce excessive hydrogen gas. This gas is usually produced when bacteria ferment carbohydrates.

  Symptoms:

  • Diarrhea (most common)
  • Bloating
  • Abdominal pain
  • Gas

  Causes:

  • Low Stomach Acid: Insufficient acid allows bacteria to survive and proliferate.
  • Motility Disorders: Conditions like IBS or diabetes can slow down the movement of food and bacteria through the small intestine, allowing bacterial overgrowth.
  • Diet: High intake of fermentable carbohydrates (e.g., FODMAPs) can contribute to bacterial growth.
  • Prior Infections: Gastrointestinal infections can disrupt the normal bacterial balance, leading to overgrowth.

2. Methane-Dominant SIBO

Characteristics:
Methane-dominant SIBO involves bacteria that produce methane gas instead of hydrogen. These bacteria are often archaea, a different type of microorganism.

Symptoms:

• Constipation (most common)
• Bloating
• Abdominal discomfort
• Belching

Causes:

• Archaeal Overgrowth: Methane-producing archaea can flourish when there is a disruption in the balance of gut bacteria.
• Motility Disorders: Similar to hydrogen-dominant, slowed gut motility can allow methane-producing archaea to grow.
• Diet: Diets high in certain carbohydrates can feed these methane-producing organisms.
• Impaired Bile Flow: Conditions that reduce bile production or flow can contribute to methane SIBO

3. Hydrogen Sulfide SIBO

Characteristics:
Hydrogen sulfide SIBO is less common and involves bacteria that produce hydrogen sulfide gas. This type can be harder to diagnose since standard breath tests do not measure hydrogen sulfide directly.

Symptoms:

• Diarrhea or mixed bowel habits
• Rotten egg-smelling gas (due to hydrogen sulfide)
• Bloating
• Abdominal pain

Causes:

• Dysbiosis: An imbalance in the gut microbiome, particularly the overgrowth of bacteria that produce hydrogen sulfide.
• Diet: High intake of sulfur-containing foods (e.g., eggs, meat) can contribute to this type of SIBO.
• Gut Infections: Past infections can lead to an overgrowth of hydrogen sulfide-producing bacteria.
• Environmental Toxins: Exposure to certain toxins may contribute to an imbalance that favors these bacteria

Mixed SIBO

Characteristics:
Mixed SIBO involves a combination of hydrogen, methane, and sometimes hydrogen sulfide-producing bacteria. Patients may experience a range of symptoms that vary depending on the dominant gas produced.

Symptoms:

• Mixed diarrhea and constipation
• Bloating
• Gas
• Abdominal discomfort

Causes:

• Multiple Bacterial Overgrowth: The presence of various types of bacteria or archaea producing different gases.
• Motility Disorders: Any condition affecting gut motility can lead to mixed SIBO.
• Diet and Lifestyle Factors: A combination of factors that contribute to the growth of various bacteria in the small intestine.

Do symptoms sound familiar? Now what!?

Understanding the different types of SIBO is essential for proper diagnosis and treatment. The causes can vary, but they often involve a combination of dietary factors, motility issues, and underlying health conditions. Addressing these underlying causes is key to managing and treating SIBO effectively. We have doctors at Vytal Health who are well-versed at diagnosing and treating small intestine bacterial overgrowth, and other GI diseases. 

Testing for SIBO

Check out our blog post that dives into all things SIBO testing here. If you suspect you have it, a functional medicine provider at Vytal Health can help! Make a 15-minute FREE discovery call with our care coordinators to learn more. You deserve it.