Why trade in refined grains like white flour and white rice for their whole-grain versions? Here’s 5 good reasons. 1. You don’t miss out on nutrients in the whole grain. Refining grains—turning whole wheat berries into white flour, for example—removes the nutrient-rich bran and germ in the whole grain. That slashes the grain’s vitamins and minerals. Some (like iron and a B-vitamin called folate) get added back to “enriched” white flour. But others (like vitamin B-6, magnesium, and zinc) don’t.