I was wondering the same thing when shopping for my Liver Flush ingredients. I read all posts on curezone that had "malic acid" in them and I found only few people advising against it. I can't find these posts I initially read but these may be helpful links: //www.curezone.org/forums/m.asp?f=263&i=18
Malic acid is cheap and can be easily ordered online. I wouldn't take any chances with this. The flush may work in either case.
You may want to read more about malic acid on curezone and maybe you'll find a more satisfying explanation.