Our body normally produces between 0.6 and 1.8 liters of gas per day. Imagine a 1.5 liter bottle of water... that is the approximate amount of gas we produce. However, this amount is tremendously variable depending on the amount and type of microorganisms that we each have in our digestive tract, our INTESTINAL MICROBIOTA. This gas is released orally and rectally, as we all know, but also a large part of these gases diffuse from the intestine into the bloodstream, being transported to the lungs and released during respiration.

In our mouth and colon (large intestine), hydrogen-producing bacteria reside on a regular basis, mainly producing hydrogen when they ferment carbohydrates from the diet. When hydrogen is detected in a patient's breath, it comes from bacterial fermentation, since our cells are not capable of producing it.

People with bacterial overgrowth or SIBO are characterized by having bacteria also colonizing the small intestine. These patients will produce much more hydrogen than average and will notice abdominal distention, rumbling in the abdomen, flatulence, etc.

However, there are patients with these same symptoms who, when given a breath test in which only hydrogen is measured, hydrogen is not found to be increased... This is usually because the patient's intestine is also colonized by another microorganism, the Archaea.

Archaea are producers of methane methaneThey produce methane from the fermentation of dietary carbohydrates, and from the hydrogen produced by their neighboring bacteria. Therefore, when Archaea are present, it is usual that hydrogen is not too high because it has been consumed.

Thus, a patient with symptoms of bacterial overgrowth (gas, flatulence) who takes a breath test to be diagnosed, could have hydrogen in normal values (which could be misinterpreted as a negative diagnosis) and, however, have an overgrowth of Archaea that is generating this increase in intestinal gas. Therefore, it is essential to measure both hydrogen and methane concentration. to reach a correct diagnosis.

Remember, if you have to do a breath test to diagnose your patient, or you have to undergo a breath test to diagnose an intolerance or bacterial overgrowth, ALWAYS test for both gases.