Researchers (including at my laboratory) have investigated how the body naturally handles the occasional release of hemoglobin from aging red blood cells and from cells affected by blood diseases, such as hemolytic anemia. They have found that the body’s first line of defense against hemoglobin oxidation is a process of reduction, in which molecules like uric acid or ascorbic acid (vitamin C) impede oxidation by reducing the iron to a less oxidizing species.