I've been wondering what purpose the juice serves other than to mix with the olive oil. I just cannot hold down the lemon juice/oo mix, it sits there and burns in my stomach all night long. I've tried it 2x just to see if it was something else that caused that. I like grapefruit juice so that's not a problem for me. However, I've tried to get my daughter to do the flush and she cringes at the thought of grapefruit juice and I won't suggest the lemon juice. She just loves orange juice though so maybe there's still hope for her!!!!