Pieces of broken shells of walnuts have been found at archeological sites of places that had been inhabited 7000 BC. It is an incredibly versatile type of nut that was used as medicine in ancient Greece, and walnut extract was used even as an antidote to treat poisoning. Green walnuts contain forty times as much vitamin C as orange. It is rich in vitamins A and E, contains various types of vitamin B, e.g. thiamine, which protects the nerves and muscles and stimulates growth.