Fiber in brown rice is a nutrient found in the BRAN layer of the grain. BRAN is the outermost layer of the grain and is rich in dietary fiber, vitamins, minerals, and antioxidants. Brown rice is a whole grain that contains all three parts of the grain: the BRAN, germ, and endosperm. The BRAN layer is the most nutrient-dense part of the grain and is where most of the fiber is found. Fiber is important for digestive health, weight management, and heart health.