The Ingredients
Flour, water, salt, time. That's the whole list.
Wild starter, fed with whole flours, naturally leavened.
The wild yeast and bacteria do the heavy lifting (read: they pre-digest the bread for you). Phytic acid drops, and your gut sends a thank-you note.
That long, cold ferment is why sourdough sits gentler on the belly than the sliced stuff, and why it tastes like something.
No commercial yeast. No additives. No shortcuts. Just patience.