The history of nitrite in human nutrition: a contribution from German cookery books. In order to settle the question of when saltpetre (nitrate) came in use as an additive to human food, a number of historic cookery books from Germany and Austria were reviewed. Obviously, the change from vegetable dyes to saltpetre for the coloring or color preservation, respectively, of meat occurred between 1600 and 1750, probably near 1700. The addition of sugar which favours the reduction of nitrate to the active agent nitrite became common practice during the 19th century. Thus some historic parallels to the appearance of colorectal cancer, multiple sclerosis and rheumatoid arthritis in the medical literature became apparent. 