While many parents now days are well educated about the danger of giving their children sodas to drink, many do not know the dangerous levels of sugar many fruit juices contain. Fruit juice is not a good alternative to sodas as many of us believe it to be. This even includes juices that are labeled "no added sugar".
Fruit in its purest form contains as much or more sugar than colas as you will see in this comparison. In a 12 ounce serving of cola, there are 40 grams of sugar (10 tsp). The same amount of orange juice contains 39 grams (8 tsp), apple juice has 42 grams (10 tsp), and grape juice has 60 grams (15 tsp). You must remember that in these comparisons, it is the juice without added sugar. In many of the juices we consume we see on the label that in contains 10% or 20% real juice or reads "made from concentrate". In these cases, the liquid is replaced with water and high fructose corn syrup which adds even more sugar. Of course as a rule the less percent of juice, the more fructose is added. Our bodies can not distinguish between regular sugar and fruit sugar, as they are both processed in the same way. Over consumption of these beverages can lead to diabetes and weight gain. It can also lead to an early addiction to sugar for children, especially if introduced in a bottle or a sippy cup, along with early tooth decay.
This is not to say that children should never drink fruit juice, because it has many good qualities. Before 1970, juice was a special treat with breakfast and a small glass a day was all for the entire day. Slowly the juice industry started marketing juice as the safe alternative to sodas and we started consuming more and more. In some researches it was discovered that children 3 and 4 years old who consumed 2 or more glasses of fruit juice a day, were double the risk of becoming overweight one year later. It is recommended by the American Academy Of Pediatrics that preschoolers should be limited to 4 to 4 ounces of juice per day.
The obvious best thing for thirsty kids is water. The younger a child learns to quench their thirst without a sugary drink, the more likely they will drink water the rest of their lives. The best way to get the benefit of fruit is to eat the fruit.