Fermentation occurs in your gut (large intestine) when food is not digested fully. The undigested food passes into the large intestine where bacteria break it down. Gases like hydrogen are produced as a by product of this process.
Experiencing high fermentation levels is not necessarily a problem. However, a high amount of fermentation in people suffering with digestive issues can cause uncomfortable and distressing symptoms (e.g. pain, bloating, diarrhea, constipation) so in those cases it can be a good idea to manage the level of fermentation.
Scientists have known for thousands of years about the benefits of fermentation. Even back in the 1800s, the French pediatrician Henry Tissier gave fermentable bacteria to infants suffering from diarrhea. Today, we have learned (and are still learning!) a great deal about the benefits of colonic bacteria.
For more information on how to read your Fermentation Scores from AIRE, please see our website here: foodmarble.com/fscores