I hate to do this, but I'm always saying that I'm not a Dr and you need to find proof for yourself.  We do a lot of research before we comment on dietary and health information.

Many people find sourdough easier to digest than bread made with commercial yeast. The long fermentation gives the wild yeasts and bacteria time to break down some of the starches and proteins in the flour, including a portion of the gluten.

That long ferment also gives sourdough its tangy flavour and chewy crumb. And because the dough has had hours to develop, the finished loaf tends to keep better than a quick-yeast loaf.

Sourdough is not gluten-free. If you have coeliac disease, this bread is not for you. But for many people who feel a bit heavy after eating regular bread, a properly fermented sourdough loaf is much kinder on the gut.