. Oranges are classified as citrus fruits and it has been discovered that they reduce the risk of mouth, larynx, and stomach cancer by 50%. Broccoli when it is chewed or smashed contains small amount of a chemical called sulphorphane that has anti-cancer compound. Researchers found that raw broccoli lacks sulpharpane and has no cancer fighting power, but when broccoli is heated to 60 C it contains the anti-cancer compound at higher ratio.