It’s common knowledge that there is gas in your body. While healthy levels of these gases help
contribute to a balanced gut, abnormal levels of gases can indicate certain conditions like small
intestinal bacterial overgrowth (SIBO) and cause frustrating symptoms. There are three primary
gases found in the gut microbiome: hydrogen, methane, and hydrogen sulfide; although
hydrogen sulfide is only recently detectable through the three-gas breath test, trio-smart®.
Patients with elevated hydrogen sulfide often went unrecognized by one-gas or two-gas breath
tests prior to trio-smart’s breakthrough three-gas technology.
Measuring Only Hydrogen and Methane Is Incomplete.
Hydrogen, methane, and hydrogen sulfide interact with each other in a complex and
interesting way. Hydrogen is produced by fermenting bacteria but is also consumed by
other organisms, resulting in the production of other gases, including methane and
There is a balance-counterbalance effect between methane and hydrogen sulfide,
illustrating a biochemical interdependency between microbes in the microbiome. These
findings are important, because they indicate limitations when measuring only one or two of
the three primary fermented gases.
What Is Hydrogen Sulfide?
Hydrogen sulfide is a colorless gas often found in the gut. Hydrogen sulfide is produced
when hydrogen sulfide-producing organisms consume hydrogen and can lead to
uncomfortable GI symptoms, like diarrhea.
What Are the Symptoms of Abnormal Hydrogen Sulfide?
Patients with excess hydrogen sulfide experience symptoms like abdominal pain, bloating,
gas, distension, flatulence, and especially diarrhea. These symptoms are usually
experienced once a week or more for at least four weeks. Excess hydrogen sulfide shares
many of the symptoms of IBS-D (diarrhea-predominant irritable bowel syndrome) and IBS-
M (mixed-diarrhea/constipation irritable bowel syndrome). Abnormal levels of hydrogen
sulfide predict more severe diarrhea, and the level of hydrogen sulfide measured correlates
with the severity of diarrhea. Elevated levels of hydrogen sulfide are indicative of excess
How Do You Test for Hydrogen Sulfide?
You can measure levels of hydrogen sulfide with a breath test. While 2-gas legacy breath tests
only measure hydrogen and methane, trio-smart is the only 3-gas breath test available that
measures hydrogen sulfide, as well. Learn more about breath testing with trio-smart here.