★★★★★
Don't know about the juice but a good sized portion on fresh, not frozen pineapple is a very effective natural acting laxative.
Pineapples
★★★★★
Pineapples! Fresh pineapple juice works great. I have a juicer and have it every morning. I'm not sure about store bought seeing as they usually have additives in the juice. A juicer is the best investment you'll ever make.