Lemon is a fruit that is rich in vitamin C. When stricken with flu, lemon is a good choice to re-increase the body's resistance to disease (but this has not been proven by bird flu or swine flu). But it is true, lemon is a good fruit to be consumed by people who are suffering from disease because of the fall of endurance. This may be one of the reasons why lemon is the fruit most people bring while visiting patients in the hospital. Besides because it is good to increase endurance, lemon is also the most widely sold fruit.