Zinc gluconate is the zinc salt of gluconic acid. It is an ionic compound consisting of two moles of gluconate for each mole of zinc. Zinc gluconate is a popular form for the delivery of zinc as a dietary supplement.

Gluconic acid is found naturally, and is industrially manufactured by the fermentation of glucose, typically by Aspergillus niger, but also by other fungi, e.g. Penicillium, or by bacteria, e.g. Acetobacter, Pseudomonas and Gluconobacter.[1] In its pure form, it is a white to off-white powder. It can also be manufactured by electrolytic oxidation[2], although this is a more expensive process. The advantages are a lower microbiological profile, and a more complete reaction, yielding a product with a longer shelf life.

Zinc gluconate may interfere with the absorption of antibiotics, so combinations may be unsafe.

Ferrous gluconate is a mineral supplement. It is the form of calcium most widely used in the treatment of hypocalcemia. Calcium gluconate contains 9.3% calcium.


Ferrous gluconate is used as a food additive when processing black olives. It imparts a uniform jet black colour to the olives.[3]

Iron(II) gluconate, or ferrous gluconate,^[1] 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.[2] It is also present in the combination supplement dianazene, a vitamin mixture created by L. Ron Hubbard and used in the religion Scientology. Ferrous gluconate is 11.6% elemental iron