The entire part of the bael tree can be eaten by humans. In fact, every single part of the tree has been used for medicinal purposes for a very long time.
One of the main uses that the bael fruit is used for is to treat constipation. It is a natural laxative. When taken as a supplement for a couple of months it is thought to have a very beneficial effect on the digestive system. It cleans old fecal matter out of the intestines.
Mosts parts of the bael tree are thought to be beneficial when treating other ailments such as respiratory infections, diarrhea, and peptic ulcers.