This will probably surprise a lot of people, but fruit juice concentrate, like orange juice and apple juice, is among the health foods to avoid. How many parents think that giving you child orange juice for breakfast is a good way to start the day? How many buy those juice boxes thinking they are healthy. Yeah we are told that orange juice is healthy since you are getting vitamin C, right? Well, maybe you are but it didn't come from the oranges. It has to be added back in after processing.
Fruit juice concentrates are almost always processed by first squeezing the fruit and then cooking the juice to preserve it. Most, if not all of the fiber has been removed, as well as most of the vitamins and minerals. Vitamin C has been removed now, so it has to be added back in. Might as well drink sugar water and take a vitamin C supplement.
It also probably has had something added to it so it can sit on the grocery store shelf for a longer period of time as well as coloring, since the color was lost during the cooking process. Some companies even add flavor agents to put flavor back in since most of it is lost in processing.
Since the fiber and most of the vitamins and minerals have been removed, the juice is absorbed too rapidly, causing a sharp spike in the glucose in the bloodstream. This in turn causes the pancreas to pump out insulin and can lead to diabetes over time. It is also a contributing factor in the increase in child obesity, tooth decay and other problems including gout.
It is just empty calories. Might as well give you kid the empty juice box, at least it would have some fiber and none of the sugar.
So what about fresh squeezed juice? Well, since it hasn't been heat processed it still will retain almost all the vitamins and minerals as well as some of the fiber of the original fruit, which is contained in the membranes and pulp that get removed during heat processing of fruit juice concentrates.
Just remember, fruit juice is not fruit. Most of the benefits of fruits come from the fiber of the fruit or the skins and juicing even by hand usually removes most. There is still a lot of sugar in most fruits juices and sugar is sugar. It will still give you a rise in blood glucose and it should still be consumed in moderation. No more than 6 screwdrivers a day!