If you're looking for non-dairy sources of calcium due to lactose intolerance, dietary restrictions or personal preferences, you can find this essential mineral in many plant-based foods. Dark green vegetables, calcium-fortified tofu, wheat bread and corn or flour tortillas offer calcium, according to the Office of Dietary Supplements, or ODS. Although whole oranges offer fiber, vitamin C and potassium, they aren't particularly high in calcium. If you enjoy the taste of oranges, you can meet or exceed your daily requirements for calcium with fortified orange juice.
Calcium provides structural material for your bones and teeth. Your nerves, muscles and blood vessels require calcium to function normally. One cup of raw navel orange sections offers 71 mg of calcium, according to the U.S. Department of Agriculture, or USDA. This amount represents 7 percent of the daily value, or DV, for calcium, or the amount that a healthy person consuming a 2,000-calorie diet requires daily. Whole oranges fulfill only a small percentage of your daily requirement for this essential mineral. The recommended dietary allowance, or RDA, for calcium is 1,000 mg for males and females ages 19 through 50. The RDA for males over 50 is 1,000 mg per day, and the RDA for women over 50 increases to 1,200 mg per day.
According to the USDA, 1 cup of orange juice fortified with calcium provides 500 mg, or 50 percent of the DV. In a study published in the December 2002 issue of the “American Journal of Clinical Nutrition,” authors Ligia Martini and Richard J. Wood compared the absorption of calcium from calcium-fortified orange juice, calcium carbonate supplements and milk in a group of elderly adults. Blood tests showed that the study participants absorbed as much calcium from fortified orange juice as they did from calcium supplements or milk.
Some brands of orange juice are fortified with both calcium and vitamin D, a fat-soluble vitamin that allows your body to absorb calcium. This combination of nutrients makes fortified orange juice a healthy alternative to milk or cheese fortified with vitamin D. According to the USDA, 1 cup of orange juice fortified with vitamin D offers 137 IU, or international units, of this vitamin, which is 34 percent of the DV.
Both oranges and orange juice are naturally rich in vitamin C, an antioxidant vitamin that strengthens immunity and may counteract the cellular damage that can lead to premature aging or cancer. One cup of orange juice fortified with calcium and vitamin D also contains 84 mg of vitamin C, or 140 percent of the DV for this nutrient. One cup of fresh orange sections provides 98 mg of vitamin C, or 163 percent of the DV. Oranges and orange juice also provide potassium and vitamin A. Whole oranges are a good source of fiber, giving you 4 mg of fiber in each cup of raw orange segments, according to the USDA.