The word walnut comes from the Old English wealh-hnutu, which literally means foreign nut . The major areas of walnut production are between the 35th and 45th northern parallels. Its origin is uncertain and there are several different hypothesis, the most likely of which pointing to Central Asia in the areas closest to modern-day Iran. From there it spread to Europe thanks to Greek civilization, arriving in Greece during the times of Alexander the Great (300 B.C.), extending later to the rest of Europe and eventually to America. The largest commercial production of walnuts is in the valleys of California; walnuts consumed in Spain vary in origin, from domestic products to those from France and India, though the majority come from California. Among other positives, walnuts have been shown to be beneficial for the prevention of cardiovascular problems, something that has taken them from a holiday season item to an everyday part of our diet.