My colon hydrotherapist has done many Liver Flushes
and recommended apple pectin to replace apple juice. I find that apple juice is too sweet and makes me gain a lot of weight. I tried it, and it worked.
She recommended 500 mg capsules, 5 in the morning and 5 at night, for 9 days preceding the flush.
I know that sounds like a lot, but I've followed that advice for the last 4 flushes and every flush has produced between 200 - 400 stones. The only side effects I noticed were a small rash that has appeared around both nostrils (not the nostrils themselves). This rash might be due to the type of toxins being released or building up in my liver, so the exact origin of the rash is uncertain, but it did appear after I started using the apple pectin.
To be fair, I believe that malic acid would be better. You can get that from health food stores or even wine making stores. Also, with the last flush, I tried eating a whole apple every day for 3 days before the flush, and the rash doesn't seem to be so noticable.
At any rate, apple pectin is safe to use, at least in the short run, and you could easily supplement it with whole apples.