Betacarotene and vitamin A help in maintaining eyesight as they prevent macular degeneration which is the primary reason behind loss of vision at the old age. The vitamin C found in pineapple juice helps the body to fight against the bacteria and the toxins that invade the human gum tissues. Quite often the extracts of pineapple fruit are used by many as dietary supplements. It has also been found that pineapple juice helps strengthen the human bones. This is mainly because of the manganese that is found in pineapple juice.