In most bread products, we flag ingredients like wheat, barley, or spelt, because they contain moderate to high levels of fructan. In sourdoughs however, we often do not flag these ingredients, because the fructans are reduced to acceptable levels during the fermentation process.
The only exception to this rule is when yeast also appears on a sourdough product ingredient list. Yeast is often added to speed up the fermentation process, which in turn keeps the fructan load relatively high. Thus, if you scan a sourdough and it comes back yellow or red, it is likely because of yeast.
If you’re still confused or need a little extra help finding a green light sourdough, check out this bread post written by FODMAP-trained dietitian, Vanessa Vargas. Lots of great options there!