There are two important points about flour to understand. There’s stone-milled flour and roller-milled flour. The first is what it sounds like, two stones that grind together, milling wheat berries between them. That’s the ancient way. The modern way involves factory roller mills that process more flour more effectively. The problem with roller mills is the flour they produce is less nutritious. That niacin, thiamin, iron, and riboflavin on the label is added enrichment because the natural equivalent was removed—it attracts insects and spoils.