King Vitamin is a pre-sweetened cereal produced by Quaker Oats and sold in the United States. The cereal entered the marketplace in 1970, and although it has changed mascots over the years, it is still in production. King Vitamin cereal boasts high vitamin and iron content, in addition to a more modest amount of sugar (only 6 grams - such as Cap'n Crunch and Lucky Charms contain 13 grams or more).