Oat flour is made by grinding steel cut oats into a fine powder. It is rich in calcium, magnesium, iron, thiamin, phosphorus and zinc. It is high in fiber and protein. Oat flour is said to reduce cholesterol in people who have high cholesterol. Oat flour has a sweet nutty flavor. It works well in baked goods. Oat flour can be bought in grocery stores or can be purchased online. Store oat flour in an airtight container in a cool dry place and it will stay fresh for 2 to 3 months. You can refrigerate the oat flour for one year.