Fruit juice, though tasty and refreshing, is not as healthy as whole fruit. When a whole fruit is pressed or squeezed to make juice, some of the nutrients, most notably fiber and the water-soluble vitamins, are lost in the process. While 100% fruit juice is not completely devoid of nutrients, it is undoubtedly less nutrient dense than the whole fruit that it came from. Orange juice makes a good example of the health difference when you focus on the issue of its pulp. The white pulpy part of the orange is the primary source of its flavonoids. Flavonoids are colorful pigments that support numerous metabolic processes in the body. The juicy orange-colored sections of the orange contain most of its vitamin C. In the body, flavonoids and vitamin C often work together, and support health through their interaction. When the pulpy white part of the orange is removed in the processing of orange juice, the flavonoids in the orange are lost in the process. This loss of flavonoids is one of the many reasons for eating the orange in its whole food form (even if you only end up eating a little bit of the white pulpy part).
Additionally, many fruit juices that are sold in supermarkets contain only a small percentage of real fruit juice, and contain added sweeteners (sucrose or high fructose corn syrup). As a result, it is easy to consume a large amount of calories without getting any actual nutrition when you consume these beverages. Make sure you read fruit juice labels carefully! Turn over on the back of the jar or bottle, and look over the ingredient list - you may be surprised to see exactly where the fruit itself fits in!