A course of broad-spectrum antibiotics is like a forest fire. It burns down the infection, but it also incinerates the "old growth forest" of your beneficial microbiome. Species like Bifidobacterium and Lactobacillus are often collateral damage.

In the world of baking, the word "yeast" is used carelessly. We treat the beige granules in a packet and the wild population in a sourdough starter as if they are the same organism just living at different speeds. They are not.