Of course it's fine as long as it's not the one with fruit juice added. . Regular V8 is too although it has too much salt for some of us.
Check out the Phase I Food List in the FAQ.
I got it Ruth, I was looking there just now lol, I gave my book away last year like an idiot, (thought I knew it all) and couldnt remember, I will go get my low sodium v8 right now