The nutritional value of rice can vary, depending on variety. White rice is usually considered to have a significantly reduced nutritional value, because the process of polishing the rice removes most of its nutrients and fatty acids. Even when white rice is enriched with vitamins B1 and B3 and iron, it still has lost much of its nutritional value. Rice is, however, considered an important world crop, since it is a staple food for about half of the world's people. Brown rice is considered far more nutritious than white rice, since it usually undergoes far less processing, and is generally allowed to retain most of its nutrition.
While both brown and white rice contain about 170 calories per serving of 0.25 cups (0.06 liters), the nutritional value of rice of each type can be significantly different. Brown rice is generally considered a good dietary source of vitamins B1, B6, and B3, as well as phosphorous, manganese, dietary fiber, iron, and essential fatty acids. Brown rice is also considered a good source of tryptophan, selenium, and magnesium. The nutritional value of rice that has not been polished during processing makes it a good source of fatty acids, dietary fiber, and complete protein.
White rice loses many of these vitamins and minerals in processing. The hulling and polishing of white rice can reduce its vitamin B1 content by up to 80 percent, its B6 content by up to 90 percent, and its B3 content by more than 60 percent. White rice also typically loses about 60 percent of its iron content, along with all of its fatty acids and dietary fiber, in processing. Vitamins and minerals are often added to white rice after processing, but this process of enrichment does not generally replace most of the nutrients lost from the rice during processing.
White and brown rice alike are considered very low in fat, cholesterol, and salt. The nutritional value of rice of both types may rest on the large amounts of complex carbohydrates they provide. Rice's nutritional value as a source of carbohydrates has made it a dietary staple for much of the global populous. A diet based on whole grains like rice is said to help maintain healthy body weight, support cardiovascular health, lower cholesterol, and prevent type 2 diabetes.