Citrus fruit is said to be very cleansing to the body including the liver. I have read anecdotal articles that lemon juice causes the gallbladder to contract. (I don't know if this is a scientific fact or not) My Naturopath gave me an article that suggested eating the fresh juice of a lemon every morning to cleanse the gallbladder and keep it free of stones.
I have done several very successful flushes using apple juice. In fact last night I flushed with apple juice, a little lemon juice and olive oil, then drank a few ounces of Coke. The Coke has phosphoric acid that is supposed to soften stones and it cuts the oily feel in my mouth. This morning I passed hundreds of stones. This is by far the most productive flush I've done since I went on maintanence flushing. As I wrote earlier stress, pain medication and bad diet have produced more stones.