im not sure about that but I read a book from the juice master called slim 4 life (you may not want to slim) but he talks about all the stuff that go into this drinks and they really aint good I suggest any one buy the book so you no what you are putting in yours and your childs body. (I have to admit I am not a health freak and I am finding it hard not eating and drinking the stuff) but his juices are so nice and they give plenty of enagy also my 6yr old neice and 9yr old nephew love to drink them you can even make a slush out of them with enough ice. I really do suggest you buy the book he explains so much in it.
If you are referring to the copius amounts of caffiene... then NO. That's just an old-wives tale. Caffeine DOES have other undesirable effects in children, however, and may weaken bones in older people.
In both kids AND adults, excessive consumption of caffeine can cause:
jitteriness and nervousness upset stomach headaches difficulty concentrating difficulty sleeping increased heart rate increased blood pressure