Nano Iron vs FFE3 Iron – What’s the Difference?
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Iron supplements come in a number of different forms, and the differences between them are not just marketing — they reflect genuinely different chemistry, different absorption pathways, and different practical experiences for the person taking them. This post focuses on two forms that often come up in the same conversation: nano iron and ferric iron (Fe3+).
First: The Two Types of Dietary Iron
Before comparing specific supplement formats, it helps to understand the two fundamental categories of dietary iron.
Haem iron comes from animal sources — it is derived from haemoglobin and myoglobin in meat, poultry, and fish, and exists as ferrous iron (Fe2+). It is absorbed relatively efficiently by the body.
Non-haem iron comes from plant sources and iron-fortified foods, and exists as ferric iron (Fe3+). It is less efficiently absorbed than haem iron, and its absorption is more affected by other compounds in the diet — phytates in cereals and grains, and polyphenols in tea and coffee, can reduce non-haem iron absorption by 33–50%.
Most iron supplements — whether tablets, capsules, or liquids — are based on non-haem iron in compound form.
Understanding Iron Supplement Labels: The Two Numbers
When you read the label of a standard iron supplement, you will typically see two numbers. This causes a great deal of confusion and is worth understanding clearly.
The larger number is the total weight of the chemical compound — for example, ferrous sulphate or ferrous gluconate. Iron in these supplements is bonded to a salt or carrier molecule, and the compound as a whole is heavier than the iron it contains.
The smaller number is the elemental iron — the amount of actual iron the body can potentially use. This is the number that matters. But even this elemental iron is not simply absorbed as-is: it must first be liberated from the compound within the gastrointestinal tract before the body can take it up. That liberation process occurs throughout the digestive system, primarily in the upper gut.
Most liquid iron supplements contain ferrous gluconate, which is only 12% elemental iron. Compound iron supplements generally contain between 12–15% elemental iron in compounded form. In healthy individuals, absorption from these supplements is typically 10–15% of the elemental iron present. In those with iron-deficiency anaemia, the body can upregulate this to around 50%. In people with malabsorption conditions, it may be considerably lower.
It is also worth noting that compound iron supplements — including tablets, capsules, powders, and liquids — can contain fillers, residues, additives, excipients, and adulterants in addition to the iron compound itself.
What Is Ferric Iron (Fe3+)?
Ferric iron is the oxidised form of iron — iron with three positive charges (Fe3+). It is the form found in most plant foods and in many supplement compounds. Because the body absorbs ferrous iron (Fe2+) more readily than ferric iron, ferric iron supplements typically require conversion to the ferrous form in the gut before absorption can occur. This adds an additional step to the absorption process and is one reason ferric iron supplements are generally considered less bioavailable than ferrous formats.
Newer ferric iron formulations have improved on this — some use carrier molecules designed to improve stability and tolerability — but the fundamental requirement for gut-based liberation and conversion remains.
The side effect profile of ferric iron supplements is generally better than older ferrous sulphate formats, but unabsorbed iron passing into the lower gut can still disrupt the gut microbiome balance in some individuals, particularly at higher doses.
What Is Nano Iron?
Nano Iron is structurally different from both ferrous and ferric compound supplements. It is 100% elemental iron — iron in its pure, uncombined form, not bonded to any salt, compound, or carrier molecule. The iron exists as perfectly spherical particles measuring between 0.5 and 7 nanometres, suspended in ultra-purified water. Those are the only two ingredients.
Because it is elemental and not a compound, there is no liberation process required in the gut. The body does not need to break anything down or convert anything before the iron can be used.
More importantly, nano iron is not primarily absorbed through the gut at all. When held in the mouth and swished gently, the nanoparticles are absorbed directly through the oral mucosa — the soft tissue lining of the mouth including the gums, cheeks, and lips. The particles bypass the digestive tract entirely. This is why nano iron does not carry the gastrointestinal side effects associated with compound iron supplements — there is simply no unabsorbed iron passing into the lower gut to cause disruption.
The particles are also under 10 nanometres in size — small enough to pass through the blood brain barrier, the membrane that restricts access to the central nervous system based on particle size.
How Do They Compare?
| Feature | Nano Iron | Ferric Iron (Fe3+) |
|---|---|---|
| Iron form | 100% elemental (Fe⁰) — unbound | Ferric iron bound to a compound |
| Ingredients | Iron + purified water only | Iron compound + typically fillers, excipients |
| Absorption route | Oral mucosa (mouth tissue) | Gastrointestinal tract |
| Gut liberation required? | No | Yes |
| Conversion required? | No | Yes (Fe3+ → Fe2+ in gut) |
| Gut side effects | None — bypasses gut | Possible at higher doses |
| Taste | Tasteless and odourless | Often metallic |
| Additives | None | Varies by product |
| Suitable from | 0 years (whole family) | Varies by product |
| Pregnancy/breastfeeding | Yes — follow HCP guidance | Varies — follow HCP guidance |
Which Is Right for You?
This is a question best answered with your GP or healthcare professional, particularly if you have been prescribed a specific iron intake or are managing a health condition. What the comparison above shows clearly is that the two formats work in fundamentally different ways — they are not simply different doses of the same thing.
Nano Iron is available from us in 500 ml and 1000 ml bottles. The 1000 ml offers better value for regular use or households where more than one person is taking it.
References
- Oral iron supplementation: new formulations, old questions — haematologica.org
- The Effects of Nanoparticles Containing Iron — pmc.ncbi.nlm.nih.gov
- Nanoparticulate iron(III) oxo-hydroxide delivers safe iron — pmc.ncbi.nlm.nih.gov
- A metal-polyphenol network-based iron supplement — sciencedirect.com
Further Reading
For the full science behind how nano iron works — including oral mucosa absorption, the Miron glass, and how to read the two numbers on iron supplement labels — see our nano iron science overview. For practical guidance on dosing, timing, and method, our complete guide to using nano iron covers everything. Both are part of our natural supplements range.
