Five sections on iron: the route through the small intestine, the cells that keep it in reserve, the sensors that read its supply, intake tables, and, at the end, the text of the EU claim itself.
Food supplies iron in two chemically different forms. Heme iron comes from animal tissue and is taken up by the cells of the intestinal lining in a comparatively direct way. Non-heme iron comes mainly from plant foods and needs an extra step: an enzyme at the intestinal wall first converts it into a charge state it can absorb, before a dedicated channel protein moves it into the cell.
How much of that actually ends up in the body also depends on what else is in the meal. Vitamin C clearly favors the absorption of non-heme iron, while phytic acid from grains and legumes, along with tannins from coffee or black tea, tend to slow it down. Leaving some time between an iron-rich meal and a cup of coffee can measurably raise absorption as a result.
| Food | Iron |
|---|---|
| Lentils, cooked (1 cup) | approx. 6.6 mg |
| Beef, lean (150 g) | approx. 3.0 mg |
| Pumpkin seeds (30 g) | approx. 2.5 mg |
| Whole-grain bread, two slices of 40 g each | approx. 1.8 mg |
| Spinach, cooked (100 g) | approx. 2.7 mg |
The EU reference value for daily intake is 14 mg for adults. It's meant for package labeling, not as an individual's personal requirement.
Red blood cells renew themselves continuously: after about 120 days, older ones are recognized and taken up by specific cells in the spleen, liver, and bone marrow. The iron bound inside them gets released in the process, instead of simply disappearing.
Part of this released iron leaves the receiving cell again and reaches a carrier protein in blood plasma, which passes it on to other tissues. Another part stays stored inside that same cell for the time being — more on that in the next section.
A liver-hormone axis continually fine-tunes this process to the current supply: when the amount available in the blood rises, a peptide hormone made by the liver pushes back against release from the storage cells; when it falls, that signal eases off, and more iron leaves the storage cells. This interplay is purely cell physiology and stands apart from the authorized wording.
The spleen and the bone marrow are also places where immune cells arise or come together. This double role — a building site for immune cells and a spot for iron reprocessing in one — forms part of the research background against which the claim quoted at the start was reviewed.
Free iron is chemically restless: it reacts readily with oxygen and can form byproducts that attack cell components in the process. To keep that risk small, the body binds most of its iron to proteins instead of letting it circulate freely.
The most important storage protein of this kind is ferritin: a spherical shell made of 24 subunits, inside which several thousand iron ions can settle in a chemically calm form. Ferritin turns up in practically every cell type, but in especially noticeable amounts in the cells that break down older red blood cells — in other words, exactly the cells of the spleen, liver, and bone marrow described in the previous section.
Europe's food-safety regulator, EFSA, weighed the scientific evidence on iron and the subject covered in this section. The European Commission then added the wording below to its list of authorized claims:
“Iron contributes to the normal function of the immune system”
EU-authorized wording · Regulation (EU) No 432/2012
The wording itself names neither ferritin nor any single organ. It records only the reviewed overall result — the sections above simply provide the biological background against which that review took place.
How much ferritin and how much uptake protein a cell makes at any given moment isn't a fixed quantity. Two related sensor proteins inside the cell continually check how much iron is freely available right now, and adjust which messenger RNA gets read as a result.
When little free iron is available, these sensor proteins dock onto specific sections of the messenger RNA for ferritin and slow down its translation — at that moment, the cell makes less storage protein because there's less to store. At the same time, they leave the messenger RNA for the surface uptake protein untouched, so more of it gets made and the cell can pull in extra iron from the blood. When the free iron supply rises again, this pattern reverses.
This process works on the same basic principle in nearly every cell in the body, including the cells described earlier in the Cornerstones. It's scientific background from cell biology, and it supplements the official wording without being part of it.
Iron also has several other claims, each reviewed and authorized separately, covering other body functions. Those remain legally separate cases; the Cornerstones stick strictly to the claim on the immune system.
The wording addresses the adult population as a whole; it doesn't set any age cutoff within that group. An assessment for children or teenagers belongs with a doctor or a registered dietitian.
The claim doesn't name a specific cell type, a single organ, or any amount above ordinary needs. It makes no statement about a state that departs from ordinary supply, and it doesn't describe this process being stepped up through a particularly high intake.
No. The Cornerstones put published research into context for a general audience. Testing, results, and advice remain the job of medical professionals.
The ferritin level in blood is sometimes used in medical labs as one factor among several to help gauge iron status. Interpreting a result like that remains the job of medical professionals and isn't the subject of this page.
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This page brings together generally available knowledge about iron and is meant as nutrition information, not as a remedy or a diagnostic tool. A supplement can't recreate a varied, well-rounded diet; the amount stated on a package should be read as an upper limit, not as a target. Products like this belong somewhere children can't reach.
Anyone with a medical condition, who is pregnant, nursing, or taking medication is best off discussing their own diet in person with a doctor or a registered dietitian before changing anything about it. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
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