... China in the 7th century when the king of Nepal sent it as a gift to this ... country. Spinach is known as a rich source of iron and calcium. According to the USDA, a ... steamed, or quickly boiled. Spinach is an excellent source of vitamin K, vitamin A, manganese, folate, magnesium, iron, ... , and vitamin B6. It is a very good source of dietary fiber, copper, protein, phosphorus, zinc and vitamin E. ...