Juicing probably is not any healthier than eating whole fruits and vegetables. Juicing extracts the juice from fresh fruits or vegetables. The resulting liquid contains most of the vitamins, minerals and plant chemicals (phytonutrients) found in the whole fruit. However, whole fruits and vegetables also have healthy fiber, which is lost during most juicing.
Proponents say that juicing is better for you than is eating whole fruits and vegetables because your body can absorb the nutrients better and it gives your digestive system a rest from working on fiber. They say that juicing can reduce your risk of cancer, boost your immune system, help you remove toxins from your body, aid digestion, and help you lose weight.
But there's no sound scientific evidence that extracted juices are healthier than the juice you get by eating the fruit or vegetable itself. On the other hand, if you don't enjoy eating fresh fruits and vegetables, juicing may be a fun way to add them to your diet or to try fruits and vegetables you normally wouldn't eat. You can find many juicing recipes online or mix up your own combinations of fruits and vegetables to suit your taste.
If you do try juicing, make only as much juice as you can drink at one time because fresh squeezed juice can quickly develop harmful bacteria. And when juicing, try to keep some of the pulp. Not only does it have healthy fiber, but it can help fill you up. If you buy commercially produced fresh juice from a juicing stand or store, select a pasteurized product. Note that juices from some fruits and vegetables can contain more sugar than you might realize, and this can add unwanted calories and lead to weight gain.
(info from mayoclinic.com)