The milling process determines the nutritional value of the wheat berry: stone-milling preserves the nutritional integrity of the grain as it is crushed in flour in between two granite stones. All goes in, all goes out.
Roller-milling discards the germ and bran- the most nutritionally important aspect of the wheat berry- because it cracks and chaffs the grain through a series of rolling pins. Only the endosperm is retained, which gives the product a longer shelf-life but divorces the nutrition of the germ and bran from the flour. 95% of all wheat products- from breads to cakes, pastas to couscous, pastries to cookies- are made with refined, rolled-milled white flour.