Hydrogen Sulfide Intestinal Overgrowth (SIBO and LIBO)

Sulfur Metabolism:

  • Sulfur is an essential mineral, meaning, that the body can’t make this on its own; it needs to acquire this from the diet.  Sulfur, after calcium and phosphorus, is the most abundant mineral found in the body.
  • Sulfur coveys a large range of health benefits in the body, including that it is used as a building block for certain essential amino acids. Sulfur is used in the metabolism of some medications (including antibiotics). It is also used in various treatments, including for acne and rosacea. It also plays a very important role in detoxification.
  • Enzymes and cofactors help to convert sulfur, which is toxic, to non-toxic sulfate.  Some people can have genetic issues with sulfur conversion (genes that code for the enzymes that convert sulfur to sulfate).
  • If the body burden of sulfur outweighs its ability to convert sulfur, then this becomes an issue.
  • Some bacteria in your intestinal tract can utilize substrates, through a fermentation process, to make Hydrogen Sulfide (gas) H2S. These are called Sulfur Reducing Bacteria SRB.

Hydrogen Sulfide H2S

H2S is a colorless gas – also known as ‘sewer gas’ and ‘swamp gas’ because of its rotten egg smell.

Sulfur Reducing Bacteria “SRB” can be part of a balanced microbiota (collective microorganisms in your intestinal tract) and they impart benefits to us; SRB are used as significant reducers for the elimination of environmental pollution, since various SRB can oxidize toluene, ethylbenzene, benzene and xylene (the major compounds in aromatic fuel hydrocarbons). The bacteria DesulfovibrioDesulfobacteriumDesulfobacter are among the most prevalent SRB in humans.

SBR dysbiosis (overgrowth in the intestinal tract) can lead elevated sulfur levels – if this occurs in the small intestine, it is called H2S SIBO (small intestine bacterial overgrowth). If this is in the large intestine, this is H2S LIBO (large intestine bacterial overgrowth).

Sulfur is highly toxic. If the body cannot keep up with the total burden of sulfur, converting it, and detoxifying it, then this can lead to diarrhea, intestinal inflammation, abdominal pain, sulfur (rotten egg) smelling and burning flatulence and bowel movements, and headaches.

H2S can cause irritation and inflammation and it has been found at higher levels in those with Inflammatory Bowel Disorders IBD. A high level of H2S gas can cause DNA damage, inhibits cytochrome c oxidase, and inhibits butyrate oxidation.

Butyrate is a short chain fatty acid that serves as fuel for the cells that line your colon. Short chain fatty acids are a byproduct of intestinal bacteria breaking down fibers through a fermentation process. Normally, the cells along your colon, called colonocytes, receive 70% energy from the butyrate produced in your intestinal tract. Colonocytes can literally starve due to the inhibition of butyrate oxidation that is caused by hydrogen sulfide damages on gut mucosa.

Some studies use butyrate levels as a marker to assess risk of IBD relapse. These studies have shown that patients who were in remission, yet showed decreased butyrate levels, were at high risk for relapsing within weeks.

H2S Testing

Currently, there is a newer breath test on the market called the Trio Smart Breath Test. This measures methane and hydrogen in the small intestine, and H2S in the entire intestine (it cannot distinguish between the small intestine and the large intestine).

Standard SIBO Breath Testing uses lactulose as the sugar substrate, which, once swallowed, moves through the intestine and when the Archaea (methane producers) and bacteria (hydrogen producers) that are present consume it, they produce hydrogen and methane. These gases cross from the intestinal tract, into the blood stream and exchange out through the lungs; out our breath and are measured through this breath test. If both hydrogen and methane gasses are flat lined (< 0-2 ppm), and you are experiencing SIBO symptoms (loose stool, bloating, etc.,) and you have diarrhea, then H2S should be considered.

Why is it important that methane is indeed flat lined when screening for H2S? If SRB are present at large enough numbers, they will be more efficient over methane producers, at stealing the hydrogen that is produced by your gut bacteria. SRB show greater taxonomic diversity in the microbiota than the methanogens and are able to utilize a wider range of substrates for growth. This is why we look for flat lined methane to be an indication of the presence of hydrogen sulfide. Yet, this isn’t 100% inclusive of H2S.

  • If you are also experiencing a burning sensation (heat) and/ or you note the classic rotten egg smell to your flatulence or your bowel movements, then you are a good candidate to move forward with H2S treatment.
  • If you are not experiencing these symptoms, then consider running another breath test with glucose or fructose as the substrate (it is possible that the type of SIBO present, does not readily break down lactulose and a flat lined test may be a false negative. Using another substrate may unmask SIBO).

How to balance sulfur and treat HS2 SIBO or LIBO Directly

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