Oranges are among the world’s most popular fruits. Also called sweet oranges, they grow on orange trees (Citrus x sinensis) and belong to a large group of fruits known as citrus fruits. Their true origin is a mystery, but the cultivation of oranges is thought to have started in eastern Asia thousands of years ago. Today, they are grown in most of the warmer regions of the world, and are consumed either as fresh fruits or juice. Oranges are a healthy source of fiber, vitamin C, thiamin, folate and antioxidants. In addition to being really tasty, they have several interesting health properties.
Carbs
Oranges are mainly composed of carbs and water, and contain very low amounts of both protein and fat. They are also low in calories. Simple sugars, such as glucose, fructose and sucrose, are the dominant form of carbohydrates in oranges. They are responsible for the sweet taste. Despite their sugar content, oranges have a low glycemic index, ranging from 31 to 51 (1). This is a measure of how quickly the sugar enters the bloodstream after a meal. Low values on the glycemic index are associated with numerous health benefits (2). The low glycemic index is explained by the fact that oranges are rich in polyphenols and fiber, which moderate the rise in blood sugar (3).
Fiber
Oranges are a good source of fiber. One large orange (184 g) contains around 18% of the daily recommended intake (4). The main fibers found in oranges are pectin, cellulose, hemicellulose and lignin. Dietary fiber has been associated with many beneficial health effects. In general, fibers are renowned for improving the function of the digestive system and feeding the friendly bacteria that reside there (5, 6). Fiber may also promote weight loss (7) and lower cholesterol levels (8).
Bottom Line: Oranges are a good source of fiber, which may promote digestive health.
Vitamins and Minerals
Oranges are a good source of several vitamins and minerals, especially vitamin C, thiamin, folate and potassium.
- Vitamin C: Oranges are an excellent source of vitamin C. One large orange can provide over 100% of the daily recommended intake (4).
- Thiamin: One of the B-vitamins, also called vitamin B1. Found in a wide variety of foods.
- Folate: Also known as vitamin B9 or folic acid, folate has many essential functions and is found in many plant foods.
- Potassium: Oranges are a good source of potassium. High intake of potassium can lower blood pressure in people with hypertension and has beneficial effects on cardiovascular health (9).
Bottom Line: A number of vitamins and minerals are found in oranges. These include vitamin C, thiamin, folate, and potassium.
Other Plant Compounds
Oranges are rich in various bioactive plant compounds. Plant compounds are believed to be responsible for many of the beneficial health effects of oranges. The two main classes of antioxidant plant compounds in oranges are carotenoids and phenolics (phenolic compounds).
Phenolics
Oranges are an excellent source of phenolic compounds, especially flavonoids, which contribute to most of their antioxidant properties.
- Hesperidin: A citrus flavonoid that is one of the main antioxidants found in oranges (10). It is associated with several health benefits (11, 12).
- Anthocyanins: A class of antioxidant flavonoids found in blood oranges, which makes their flesh red.
Carotenoids
All citrus fruits are rich in carotenoids, a class of antioxidants that is responsible for their orange color.
- Beta-cryptoxanthin: One of the most abundant carotenoid antioxidants found in oranges. The body is able to convert it into vitamin A.
- Lycopene: An antioxidant found in high amounts in red-fleshed navel oranges (Cara cara oranges). It is also found in tomatoes and grapefruit and has various health benefits (13).
Citric Acid
Oranges, and other fruits of the citrus family, are high in citric acid and citrates, which contribute to the sour taste. Research indicates that citric acid and citrates from oranges may help prevent kidney stone formation (14, 15).
Bottom Line: Oranges are a rich source of several antioxidants that are responsible for many of their health benefits.
Health Benefits of Oranges
Studies in both animals and humans indicate that regular consumption of oranges is associated with various health benefits.
Heart Health
Heart disease is currently the world’s most common cause of premature death. Flavonoids in oranges, especially hesperidin, may have protective effects against heart disease (11, 16). Clinical studies in humans have found that daily intake of orange juice for 4 weeks has a blood-thinning effect (17) and may reduce blood pressure significantly (11). Fibers also seem to play a part. Intake of isolated fibers from citrus fruits has been shown to decrease blood cholesterol levels (8). Taken together, it is likely that regular consumption of oranges may help lower the risk of heart disease.
Bottom Line: As a good source of antioxidants and fiber, oranges may cut the risk of heart disease.
Prevention of Kidney Stones
Oranges are a good source of citric acid and citrates, which are believed to help prevent kidney stone formation. Potassium citrate is often prescribed to patients with kidney stones. Citrates in oranges seem to have similar effects (14, 15).
Bottom Line: Being a rich source of citric acid and citrates, oranges may help prevent kidney stone formation.
Prevention of Anemia
Anemia, the decrease in the amount of red blood cells or hemoglobin in the blood, is often caused by iron deficiency. Although oranges are not a good source of iron, they are an excellent source of organic acids, such as vitamin C (ascorbic acid) and citric acid. Both vitamin C and citric acid can increase the absorption of iron from the digestive tract (18, 19). Therefore, when eaten with iron-rich food, oranges can help prevent anemia.
Bottom Line: Oranges are not rich in iron. However, when eaten with iron-rich food, they may contribute to improved iron absorption and reduce the risk of anemia.
Whole Oranges vs. Orange Juice
Orange juice is a very popular drink throughout the world. One of the main differences between orange juice and whole oranges, is that juice is much lower in fiber (4). This decrease in fiber seems to increase the glycemic index slightly (1). A cup of orange juice has a similar amount of natural sugar as two whole oranges (4), and is much less fulfilling. As a result, fruit juice consumption can often become excessive and may contribute to weight gain and harmful effects on metabolic health (20, 21, 22). Quality orange juice can be healthy in moderation, but whole oranges are generally a much better choice.
Bottom Line: Eating whole oranges is generally healthier than drinking orange juice. Fruit juices tend to be high in sugar, and not as filling as whole fruit.
Adverse Effects
In short, oranges don’t have many known adverse effects in healthy people. Some people have an allergy to oranges, but this is rare. In people who suffer from heartburn, consumption of oranges may make symptoms worse. This is because oranges contain organic acids, mainly citric acid and ascorbic acid (vitamin C).
Bottom Line: Some people are allergic to oranges, and their acidity may increase symptoms of heartburn.
Summary
Being among the world’s most popular fruits, oranges are both tasty and nutritious. They are a good source of vitamin C, and several other vitamins, minerals, and antioxidants. For this reason, they may cut the risk of heart disease and kidney stones. Simply put, oranges are an excellent addition to a healthy diet.
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