Iron(II) gluconate, or ferrous gluconate is a black compound often used as an iron supplement. It is the iron(II) salt of gluconic acid. It is marketed under brand names such as Fergon, Ferralet and Simron. Ferrous gluconate is effectively used in the treatment of hypochromic anemia. The use of this compound compared with other iron preparations results in satisfactory reticulocyte responses, a high percentage utilization of iron, and daily increase in hemoglobin that a normal level occurs in a reasonably short time. Ferrous gluconate is also used as a food additive when processing black olives. It is represented by the food labeling E number E579 in Europe. It imparts a uniform jet black color to the olives.Therefore, regular consumption of blackened olives may help to keep a healthy ferritin level in the blood.