Nitrite is a safe food additive that has been used for centuries to preserve meats, fish and poultry. It is also partly responsible for the characteristic flavor, color and texture of some processed meats. Nitrites guard against botulinum. The human body generates much greater nitrite levels than are added to food. Nitrates consumed in foods such as carrots and green vegetables are converted to nitrite during digestion. Nitrite in the body is instrumental in promoting blood clotting, healing wounds and burns, and boosting immune function to kill tumor cells.