Orange juice is great if it's raw. If it's been pasteurized then it's devoid of enzymes, and therefor your body will not digest it correctly. Without those vital enzymes your body misses out on most of the benefit. You can find raw orange juice sometimes at Trader Joe's or you can make your own orange juice at home.
Orange juice is a popular beverage. It is a source of vitamin C (ascorbic acid), potassium, folic acid (Vitamin B9). Citrus juices also contain flavonoids that are believed to have beneficial health effects. However, if drunk on an empty stomach, orange juice can exacerbate present gastro-intestinal conditions and/or cause mild and temporary stomach upset. Due to the citric acid, orange juice typically has a pH of 3.5. Drinking or sipping orange juice can therefore cause erosion of the tooth enamel, otherwise known as 'acid erosion'. It is recommended to use a straw so that the juice does not come into contact with the teeth. 200 ml (about 7 ounces) of orange juice accounts for 1 of the recommended 5 pieces of fruit a day.