I know this is a very old post Tony but do you still believe baking soda destroys vitamin C? I haven't found any evidence that it does. What it does seem to do is to convert ascorbic acid it to sodium ascorbate, which of course is highly useable by the body as an antoxidant.
If you know any sources that disagree with this please let me know. I'm no expert chemist but I don't think Linus Pauling would have added baking soda to ascorbic acid without some thought as to whether it made the viatmin C useless or not