The origin of citrus is not clearly documented, although most researchers agree on South East Asia, 4000 years BC. There are many different claims and legends surrounding citrus in general, from the Moors to the Chinese, the Egyptians to the Spanish, either way, the spread of citrus fruits from Asia to Europe was slow.   Citrus were taken to North Africa to the markets and bazaars of exotic locations, and then via the fall of the Roman Empire, they entered southern Europe and flourished in the Middle Ages.   Citrus were brought to America by the Spaniards (Columbus took seeds in his second trip) and the Portuguese in their exploration trips to the New World around 1500. International trade in fresh citrus began almost two centuries ago and it was instrumental in the containing of the terrible scurvy disease suffered by sailors during long voyages through lack of vitamin C.   The story of vitamin C began hundreds of years ago before the beginning of modern chemistry. Many people suffered from a disease called "spring sickness" or scorbutus. Today, this disease is known as scurvy. Sailors were particularly susceptible. In the last part of the eighteenth century, sauerkraut and citrus fruit were taken along on English ships bound on long voyages. Captain James Cook was a pioneer in the maintenance of citrus fruit during his marvellous voyages of discovery and the British Admiralty was quick to establish the regime.   Capt Arthur Phillip also insisted on citrus during the arduous First fleet trips to Sydney town and it was noted that scurvy was virtually eliminated even though the convicts suffered terrible conditions. Now you can realize why British sailors are called "limeys". But it wasn't until 1932 that the chemical in these foods, named ascorbic acid, was purified in a laboratory. It is found in many fresh fruits and vegetables; citrus is an excellent source.   Ascorbic acid, or vitamin C, is now known to be extremely important for the body's manufacturing of collagen, the protein responsible for keeping cells, muscles, and bones connected to each other.   The health benefits of consuming citrus are well known and today it is among the most preferred and consumed fruit in the world.