Unlike oranges or lemons, it's difficult to squeeze an eggplant by hand to get juice. Instead, you'll need a juicer or masher to extract liquid. Juicing the vegetable removes much of the natural fiber content found in the pulp. Nonetheless, eggplant juice contains valuable nutrients including vitamin C, folate, phosphorus and potassium. If you can stomach the taste, drink eggplant juice raw -- it retains more nutrients than boiled juice.