- Energy value (calories per serving): Low
- Protein: Low
- Fat: Low Saturated fat: Low Cholesterol: None
- Carbohydrates: High
- Fiber: High
- Sodium: Low
- Major vitamin contribution: Folate, vitamin C
- Major mineral contribution: Potassium
About the Nutrients in This Food
Oranges are high in sugars and soluble dietary fiber (pectins), one of the best sources of vitamin C, which is concentrated in the white tissue just under the skin, and an excellent source of the B vitamin folate.
One cup fresh orange juice (with pulp) has 0.5 g dietary fiber, 74 mcg folate (19 percent of the RDA), 124 mg vitamin C (1.5 times the RDA for a woman, 1.4 times the RDA for a man), and 496 mg potassium.
One small orange, 2.4-inch diameter, has 2.3 g dietary fiber, 29 mcg folate (7 percent of the RDA), 51 mg vitamin C (68 percent of the RDA for a woman, 57 percent of the RDA for a man), and 178 mg potassium.
The Most Nutritious Way to Serve This Food
Freshly sliced, quartered, or squeezed.
Buying This Food
Look for: Firm fruit that is heavy for its size; the heavier the orange, the juicier it is likely to be. The skin on juice oranges (Valencias from Florida)
should be thin, smooth, and fine-grained. The skin on navel oranges, the large seedless “eat- ing orange,” is thicker; it comes off easily when you peel the orange.*
Storing This Food
Refrigerate oranges if you plan to keep them for longer than a week or two.
Refrigerate fresh orange juice in a tightly closed glass bottle. The key to preserving vitamin C is to protect the juice from heat and air (which might seep in through plastic bottles). The juice should fill the bottle as high as possible, so that there is very little space at the top for oxygen to gather. Stored this way, the juice may hold its vitamin C for two weeks. Frozen juice should be kept frozen until you are ready to use it; once reconstituted, it should be handled like fresh juice.
Preparing This Food
Oranges may be waxed to prevent moisture loss and protect them in shipping. If you plan to grate orange rind and use it for flavoring, scrub the orange first to remove the wax. Do not grate deeper than the colored part of the skin; if you hit the white underneath, you will be getting bitter-tasting components in with the rind.
Orange peel contains volatile fragrant oils whose molecules are liberated when the skin is torn and its cell walls ruptured. These molecules are also more fragrant at room tem- perature than when cold. “Eating oranges” have a much truer aroma and flavor if you let them come to room temperature before peeling and serving.
What Happens When You Cook This Food
Heat destroys the vitamin C but not the flavoring oils in an orange. When oranges or orange peel are cooked, they add flavor but no noticeable amounts of vitamin C.
How Other Kinds of Processing Affect This Food
Commercially prepared juices. How well a commercial orange juice holds its vitamin C depends on how it is prepared, stored, and packaged. Sealed cans of orange juice stored in
* Oranges look most appetizing when they are a deep, vibrant orange, but on the tree a mature orange is usually green-skinned. It will turn orange only if it is chilled and the cold temperature destroys green chlorophyll pigments, allowing the yellow carotenoids underneath to show through. In a warm climate, like the Mideast, oranges are always green, but in the United States oranges are green only if they are picked in the fall before the first cold snap or if they are picked early in the spring when the tree is flooded with chlorophyll to nourish the coming new growth. Green oranges will also change color if they are exposed to ethylene gas which, like cold, breaks down the chlorophyll in the orange’s skin. (Ethylene is a natural chemical found in all fruits that encourages them to ripen.) Oranges may also be dyed with food coloring.
the refrigerator may lose only 2 percent of their vitamin C in three months. Prepared, pas- teurized “fresh” juices in glass bottles hold their vitamin C better than the same juice sold in plastic bottles or waxed paper cartons that let oxygen pass through. Oranges are not a natural source of calcium, but some orange juices are calcium-fortified.
Canned oranges and orange juice retain most of their vitamin C. As soon as the can is opened, the oranges or juice should be removed and transferred to a glass containers to prevent the fruit or juice from absorbing lead used to seal the can. The absorption of lead is triggered by oxygen, which enters the can when the seal is broken. No lead is absorbed while the can is intact.
Since 2000, following several deaths attributed to unpasteurized apple juice contami- nated with E. coli O157:H7, the FDA has required that all juices sold in the United States be pasteurized to inactivate harmful organisms such as bacteria and mold.
Drying. Orange peel may be dried for use as a candy or flavoring. Dried orange peel may be treated with sulfites (sodium sulfite, sodium bisulfite, and the like) to keep it from darkening. In sensitive people, sulfites can trigger serious allergic reactions, including potentially fatal anaphylactic shock.
Medical Uses and/or Benefits
Lower cholesterol levels. Oranges are high in pectin, which appears to slow the body’s absorption of fats and lower cholesterol levels. There are currently two theories about how this happens. The first is that the pectins dissolve into a gel that sops up fats in your stom- ach so that your body cannot absorb them. The second is that bacteria in the gut digest the fiber and then produce short chain fatty acids that slow down the liver’s natural production of cholesterol.
Possible lower risk of heart attack. In the spring of 1998, an analysis of data from the records for more than 80,000 women enrolled in the long-running Nurses’ Health Study at Harvard School of Public Health/Brigham and Women’s Hospital, in Boston, demonstrated that a diet providing more than 400 mcg folate and 3 mg vitamin B6 daily, either from food or supple- ments, might reduce a woman’s risk of heart attack by almost 50 percent. Although men were not included in the study, the results were assumed to apply to them as well.
However, data from a meta-analysis published in the Journal of the American Medical Association in December 2006 called this theory into question. Researchers at Tulane Univer- sity examined the results of 12 controlled studies in which 16,958 patients with preexisting cardiovascular disease were given either folic acid supplements or placebos (“look-alike” pills with no folic acid) for at least six months. The scientists, who found no reduction in the risk of further heart disease or overall death rates among those taking folic acid, concluded that further studies will be required to determine whether taking folic acid supplements reduces the risk of cardiovascular disease.
Lower risk of stroke. Various nutrition studies have attested to the power of adequate potas- sium to keep blood pressure within safe levels. For example, in the 1990s, data from the long-running Harvard School of Public Health/Health Professionals Follow-Up Study of male doctors showed that a diet rich in high-potassium foods such as bananas, oranges, and plantain may reduce the risk of stroke. In the study, the men who ate the higher number of potassium- rich foods (an average of nine servings a day) had a risk of stroke 38 percent lower than that of men who consumed fewer than four servings a day. In 2008, a similar survey at the Queen’s Medical Center (Honolulu) showed a similar protective effect among men and women using diuretic drugs (medicines that increase urination and thus the loss of potassium).
Protection against some cancers. According to the American Cancer Society, a diet high in foods rich in antioxidant vitamin C may reduce your risk of some cancers, such as cancer of the respiratory tract. In addition, oranges contain D-limonene, an aromatic compound found in citrus oils. D-limonene is a monoterpene, a member of a family of chemicals that appears to reduce the risk of some cancers, perhaps by preventing the formation of carcinogens in your body or by blocking carcinogens from reaching or reacting with sensitive body tissues or by inhibiting the transformation of healthy cells to malignant ones.
Lower risk of some birth defects. Up to two of every 1,000 babies born in the United States each year may have cleft palate or a neural tube (spinal cord) defect due to their mothers’ not having gotten adequate amounts of folate during pregnancy. The current RDA for folate is 180 mcg for a woman and 200 mcg for a man, but the FDA now recommends 400 mcg for a woman who is or may become pregnant. Taking a folate supplement before becoming preg- nant and through the first two months of pregnancy reduces the risk of cleft palate; taking folate through the entire pregnancy reduces the risk of neural tube defects.
Potassium benefits. Because potassium is excreted in urine, potassium-rich foods are often recommended for people taking diuretics. In addition, a diet rich in potassium (from food) is associated with a lower risk of stroke. A 1998 Harvard School of Public Health analysis of data from the long-running Health Professionals Study shows 38 percent fewer strokes among men who ate nine servings of high potassium foods a day vs. those who ate fewer than four servings. Among men with high blood pressure, taking a daily 1,000 mg potas- sium supplement—about the amount of potassium in two cups orange juice—reduced the incidence of stroke by 60 percent.
Antiscorbutics. All citrus fruits are excellent sources of vitamin C, used to cure or prevent the vitamin C–deficiency disease scurvy. Your body also needs vitamin C in order to convert the amino acid proline into hydroxyproline, an essential ingredient in collagen, the protein needed to form skin, tendons, and bones. People with scurvy do not heal quickly, a condition that can be cured by feeding them foods rich in vitamin C. Whether taking extra vitamin C speeds healing in healthy people remains to be proved. Oranges and other citrus fruits also contain rutin, hesperidin, and other natural chemicals known collectively as flavonoids (“bioflavonoids”). In experiments with laboratory animals, flavonoids appear to strengthen capillaries, the tiny blood vessels just under the skin. To date this effect has not been dem- onstrated in human beings.
Enhanced absorption of iron from plant foods. Nonheme iron, the inorganic form of iron found in plant foods, is poorly absorbed by the body because it is bound into insoluble compounds by natural chemicals in the plants. Vitamin C appears to make nonheme iron more available to your body, perhaps by converting it from ferric iron to ferrous iron, which is more easily absorbed. Eating vitamin C–rich foods along with plant foods rich in iron can increase the amount of iron you get from the plant—the nutritional justification for a breakfast of orange juice and cereal or bread. (See also beans, bread, flour, oats, wheat cereal.)
Adverse Effects Associated with This Food
Flare-up of aphthous ulcers. In sensitive people, eating citrus fruits may trigger an attack of aphthous ulcers (canker sores), but eliminating citrus fruit from the diet neither cures nor prevents canker sores.
Contact dermatitis. Although there is ample anecdotal evidence to suggest that many people are sensitive to natural chemicals in an orange’s flesh or peel, the offending substances have never been conclusively identified.
Aspirin and other nonsteroidal anti-inflammatory drugs (ibuprofen, naproxen, and others). Tak- ing aspirin with acidic foods and drinks such as oranges or orange juice may make the drugs more irritating to the stomach.
False-negative test for hidden blood in the stool. The active ingredient in the guaiac slide test for hidden blood in feces is alphaguaiaconic acid, a chemical that turns blue in the presence of blood. Citrus fruits or vitamin supplements containing more than 250 mg ascorbic acid may produce excess ascorbic acid in the feces, which inhibits the ability of alphaguaiaconic acid to react with blood may produce a false-negative test result that fails to disclose the presence of a tumor in the colon.