Drinking pineapple juice benefits your body due to its manganese content. Manganese helps fight the aging process by protecting your cells from free radicals toxins that cause cellular damage associated with aging and disease. It also helps your skin produce new collagen to allow for healing after injury. Men need 2.3 milligrams of manganese daily, and women should consume 1.8 milligrams. Canned pineapple juice contains 0.63 milligram of manganese per 4ounce serving, and freshsqueezed pineapple juice contains 1.3 milligrams.