Ferrous gluconate
Ferrous gluconate suppliers and sourcing guide
Ferrous gluconate is the iron (II) salt of gluconic acid, usually sold as the dihydrate. It is made by reacting calcium or barium gluconate with ferrous sulfate, or by heating ferrous carbonate with gluconic acid, and then crystallizing and drying the product. It is a fine yellowish-gray or pale greenish-yellow powder with about 12% iron that dissolves in water, and it is also used to darken ripe olives.
- Category
- Vitamins and minerals
- Also known as
- Iron (II) gluconate · Ferrous gluconate dihydrate · E579
- Facts checked
- November 2026
Forms and grades of ferrous gluconate
Suppliers sell different products under the same name. Specify the one you need.
Dihydrate powder
The standard USP or FCC grade, used in tablets, capsules and soluble fortification.
Granulated
Granules made for direct compression on tablet presses.
Food color grade
Ferrous gluconate supplied for color retention in ripe olives.
What to check on the COA
Compare each result with your own specification when the lot arrives.
- Assay
- Ferrous gluconate on the dried basis by ceric sulfate titration, against the USP or Food Chemicals Codex specification.
- Ferric iron
- A limit on oxidized iron, which rises with air and moisture exposure.
- Loss on drying
- Water content consistent with the dihydrate.
- Reducing sugars, chloride and sulfate
- Compendial limit tests for process impurities.
- Lead, arsenic and mercury
- Heavy metals by ICP-MS.
Storage, lots and expiry
Storage and shelf life
Store ferrous gluconate in tightly closed, light-resistant containers in a cool, dry place, because moisture and air turn it brown as ferrous iron oxidizes. Solutions oxidize faster than the powder. Shelf life is set by the supplier's specification, and older lots are retested for assay and ferric iron.
Lots and expiry dates
Record the assay, ferric iron result and color for each lot. Iron content is low compared with other iron salts, so confirm the dose math whenever a formula switches between iron sources.
Regulatory status
Facts from regulators and standards bodies, each linked to its source.
21 CFR 184.1308 affirms ferrous gluconate as GRAS for use in food as a nutrient supplement with no limitation other than current good manufacturing practice.
Source: ecfr.gov (opens in a new tab)21 CFR 73.160 lists ferrous gluconate as a color additive exempt from certification for the coloring of ripe olives.
Source: ecfr.gov (opens in a new tab)Health Canada's List of Food Additives with Other Accepted Uses permits ferrous gluconate as a color retention agent in ripe olives.
Source: canada.ca (opens in a new tab)Health Canada's Multi-Vitamin/Mineral Supplements monograph for natural health products lists iron (II) gluconate and its dihydrate among the source ingredients for iron (Table 2).
Source: webprod.hc-sc.gc.ca (opens in a new tab)
This is general information, not regulatory advice. Status differs by country and by how the ingredient is used, so check the rules for your product and market.
Ferrous gluconate suppliers
Manufacturers and distributors whose own websites say they sell it.
We are checking ferrous gluconate suppliers now
Every listing is checked against the supplier’s own website before it goes live, so this list fills in over the coming weeks. The specs and COA checklist above are ready today.
Sell ferrous gluconate? Request a listingFrequently asked questions
What forms of ferrous gluconate can brands buy?
Common forms include dihydrate powder, granulated and food color grade. Ask each supplier for the specification sheet of the exact grade they quote.
What should the COA for ferrous gluconate include?
Expect assay, ferric iron, loss on drying, reducing sugars, chloride and sulfate and lead, arsenic and mercury, each with its method, specification and result for that lot.
How should ferrous gluconate be stored?
Store ferrous gluconate in tightly closed, light-resistant containers in a cool, dry place, because moisture and air turn it brown as ferrous iron oxidizes. Solutions oxidize faster than the powder. Shelf life is set by the supplier's specification, and older lots are retested for assay and ferric iron.
What is the regulatory status of ferrous gluconate?
21 CFR 184.1308 affirms ferrous gluconate as GRAS for use in food as a nutrient supplement with no limitation other than current good manufacturing practice. 21 CFR 73.160 lists ferrous gluconate as a color additive exempt from certification for the coloring of ripe olives. Health Canada's List of Food Additives with Other Accepted Uses permits ferrous gluconate as a color retention agent in ripe olives. Health Canada's Multi-Vitamin/Mineral Supplements monograph for natural health products lists iron (II) gluconate and its dihydrate among the source ingredients for iron (Table 2).
More vitamins and minerals
- Magnesium GlycinateMagnesium bisglycinate · Magnesium bisglycinate chelate
- Vitamin CL-ascorbic acid · Ascorbic acid
- Vitamin D3Cholecalciferol · Colecalciferol
- ZincZinc citrate · Zinc gluconate
- Vitamin A palmitateRetinyl palmitate · Retinol palmitate
- Vitamin A acetateRetinyl acetate · Retinol acetate
- Beta-caroteneβ-Carotene · all-trans-beta-carotene
- Vitamin D2Ergocalciferol · Calciferol
- Vitamin E (d-alpha tocopherol)d-alpha-tocopherol · RRR-alpha-tocopherol
- Mixed tocopherolsTocopherols concentrate, mixed · Mixed tocopherol concentrate
- Vitamin K1Phylloquinone · Phytonadione
- Vitamin K2 (MK-7)Menaquinone-7 · MK-7
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