While most people think of oranges when discussing vitamin C, it’s important not to overlook pineapples. The high concentration of ascorbic acid makes this fruit a potent source of antioxidants and a key element of our diet. Pineapple juice should be consumed at least once a day if you’ve been infected by swine flu. Vitamin C functions as an antioxidant in the body, to seek our free radicals and ensure a strong immune system. This is in addition to Vitamin C’s role in the production of collagen, which is necessary for repair and regrowth throughout the body, including damage done by infections, like swine flu.