I recently gave up caffeine in an attempt to alleviate another condition I have.Consequently I've found that my fingers have not gone white despite my playing golf on Saturday mornings in low to freezing temperatures. ( I used to have to suffer for 20-30 mins until my circulation kicked in, which is painful reaction) Mindful that everyone is different, I would suggest that anyone with this debilitating condition do the same for a few months and make note of any improvement or otherwise.
Let me know if you try it and your thoughts on any changes in your symptoms. Good luck