As you probably guessed, this is referring to sourdough, also known as natural fermentation or natural leavening. Sourdough is a bread that rises without the use of packaged yeast. You’re probably aware that the way this works is the bread dough undergoes a fermentation that causes it to rise. It begins with a start that is fed and ferments. Then it can be used leaving a little behind to be fed and used again. There are many health benefits to natural leaven.
Natural leavening makes grain flours much easier to digest because the fermentation begins the digestion process before it ever enters the mouth.
Natural leavening enables nutrient absorption in the body. The phytic acid is broken down so that our bodies are better able to absorb the nutrients found in grains.