Steel-cut oats (aka Scotch oats or Irish oatmeal or pinhead oats) is unrefined and most closely resembles the natural oat grain. Rolled oats (regular or old-fashioned) are oat groats that have been steamed and rolled, reducing the cooking time to approximately 15 minutes; but more importantly the digestion and absorption time of the carbohydrates contained in the cereal. Quick oats, are groats that have been cut into pieces and rolled even finer to cook faster, about 5 minutes. Old-fashioned and quick oats can be interchanged in recipes. Instant oats are NOT interchangeable. Instant oats are made with cut groats that have been precooked and dried before being rolled. most instant oatmeal is packaged with salt, sugar and other flavorings. Oatmeal is the only food that naturally contains GLA (gamma linolenic acid) an essential fatty acid critical to the body's production of the favorable eicosanoids (PGE1 - prostaglandins). Oatmeal has been proven to lower cholesterol, reducing the risk for heart disease.