Orange fruit is low in calories, contains no saturated fats or cholesterol, but is rich in dietary fiber, pectin, which is effective in persons with excess body weight. Oranges, like other citrus fruits, is an excellent source of vitamin C. Consumption of foods rich in vitamin C helps body create resistance against infectious agents and scavenge harmful, pro-inflammatory free radicals from the blood. Oranges also are an excellent source of vitamin A. Consumption of natural fruits rich in flavonoids helps body to protect from lung and oral cavity cancers. Oranges also are an excellent source of B-complex vitamins such as thiamin, pyridoxine, and  folates. These vitamins are essential in the sense that body requires them from outside sources to replenish.