The cure to white tongues is quite simple, a non-congested non-toxic system.
The reason you have a white tongue is because your body is detoxing. Depending on which part of your tongue is coated will tell you which part of your body is congested. Bragg's book "The Miracle of Fasting" points of different parts of the tongue and what it means. Chinese medecine also uses the tongue to help diagnose, the tongue doesn't lie.
After fasting for a while, your tongue will also be clear, but it's because your body is not congested with mucus and toxins. This takes time and several fasts obviously.
So there is no easy way until your body is healthy again. My tongue has gone from all white to just the back now (intestines), but this will take time obviously to fix.