Interesting about purple grape juice.
Would a glass of dry red wine be better maybe? Seems to have a lot of anti-oxidants in it.
Of course if you don't drink at all then grape juice it is. Although you can get supplements that are made from red grapes and have anti-oxident qualities and very little carbs.

I think the French might have something there. Michael Montignac also (who's diet is almost identical to Sugar Busters) is a proponent of the benefits of red wine.