Susan, there is no need for me to explain the premise behind Gatorade. However, one needs to ask what healthy alternative can one use when they lose loads of fluids and electrolytes during prolonged physical activity.
One has to consider health/risk benefits. Is it worth drinking a beverage that is not so healthy if it reduces the risk of dehydration, cardiac arrhythmias, hypernatremia, etc.
If one is using it as an a everyday drink then I can understand why one would consider its health benefits. However, it if is used for the purposed intended, then I truly feel it is promotes good health during prolonged sporting activities where one loses body fluids as well as glucose and electrolytes.