Grapefruit is a tangy fruit which looks like an orange or sweet lime in its appearance. It’s a citrus fruit with a little hint of sweetness. It is named grapefruit due to the way it grows – in bunches like grapes grapefruit is an excellent source of vitamin C, a vitamin that helps to enhance the immune system. Vitamin C – rich foods like grapefruit may help reduce cold symptoms and the severity of cold symptoms.