Which iron is right for you?

What is iron?

Iron (Fe) is an essential trace element. It is the main component of hemoglobin (oxygen transport in the blood) and myoglobin (oxygen in muscles), and a cofactor in many enzymes. The body cannot produce iron itself and must obtain it from food or supplements.

An adult human contains about 3-4 grams of iron—a minuscule amount for such a crucial function. Most iron (approx. 70%) is found in hemoglobin, the oxygen-binding protein in red blood cells. The rest is stored in the liver, spleen, and bone marrow as a reserve form (ferritin and hemosiderin), or is found in myoglobin and a large number of enzymes involved in energy metabolism, immune function, and DNA synthesis.

Food provides two types of iron. Heme iron is found in animal tissue (especially meat, liver, fish) and is absorbed at a rate of 15-35%—a high efficiency because the iron is already bound in an easily absorbable structure. Non-heme iron is found in plant-based sources (legumes, leafy green vegetables, grains, seeds) and in most supplements. Its absorption is lower (2-20%) and highly dependent on what you eat with it. Check out our vitamin C category—vitamin C increases non-heme iron absorption by a factor of 2-4.

Iron is a mineral where both deficiency and excess can be problematic. A deficiency leads to anemia with symptoms such as fatigue, shortness of breath on exertion, concentration problems, feeling cold, and pale skin. An excess—especially in genetic disorders such as hemochromatosis—can cause long-term organ damage. Therefore, iron supplementation without a proven deficiency is less straightforward than many other supplements. If in doubt: first have ferritin and hemoglobin levels measured in the blood.

Iron and EFSA – what is scientifically recognized?

Iron has an extensive range of recognized EFSA claims, included in EU Regulation 432/2012. The following formulations may be used literally – provided the threshold is met:

"Iron contributes to the normal function of the immune system."

"Iron contributes to normal energy-yielding metabolism."

"Iron contributes to the normal functioning of the nervous system."

"Iron contributes to normal psychological function."

"Iron contributes to normal formation of red blood cells and haemoglobin."

"Iron contributes to normal oxygen transport in the body."

"Iron contributes to the reduction of tiredness and fatigue."

"Iron has a role in the process of cell division."

"Iron contributes to normal cognitive development in children."

Threshold: claims apply for a daily intake of at least 15% of the Reference Intake (RI) – which is 2.1 mg of iron per serving. Our iron supplements typically provide 14-25 mg of iron per dose, well above the threshold.

First measure, then supplement – why iron supplementation is not something to take lightly

For most vitamins and minerals, a maintenance dosage is relatively non-committal—what the body doesn't need, it excretes. Iron is different. The body does not have an active excretion pathway for iron; it is primarily lost through blood loss (menstruation, injuries, blood donation).

Therefore, long-term high-dosing without a proven deficiency is not self-evident. With a genetic predisposition to hemochromatosis (1-2% of the population has this mutation), excessive iron intake can even be harmful in the long term.

The advice: for fatigue symptoms or suspected deficiency, first have a ferritin test (the iron-storage marker) and possibly hemoglobin. The GP can request this. Only based on the results is it sensible to determine whether supplementation is necessary, and at what dosage.

The iron forms at Plenthera

Iron bisglycinate

Iron bound to two glycine molecules—a chelate with high absorption and gentle gastric tolerability. Many people who react to classic iron supplements (sulfate) with stomach complaints or constipation can tolerate bisglycinate well. Our first-line recommendation.

Heme iron (animal-based)

Iron derived from pig blood, in the natural heme form as it occurs in meat. High absorption (15-35%), hardly affected by phytates or tannins. Not suitable for vegetarians or vegans, but a logical choice for those who prefer the natural route.

Iron fumarate

Classic form with a high elemental iron content (approx. 33%). Suitable for those who want to achieve higher dosages with limited capsule size. Gastric tolerability is average—less gentle than bisglycinate, but less harsh than sulfate.

Iron + vitamin C (combined)

Iron with a vitamin C component for optimal absorption of non-heme iron. Ideal for vegans and vegetarians. Can be more practical than two separate supplements.

Liquid iron (herbal preparations)

Liquid formulas often combined with herbs, bee honey, vitamin B and C. Mild taste, popular for those who don't want capsules and for children.

How do you use iron?

Simple basic approach for iron supplementation:

1. If in doubt or experiencing fatigue: first have ferritin and hemoglobin levels measured in the blood.
2. Choose a tolerable form: bisglycinate is the best first choice for most people.
3. Preferably take iron on an empty stomach for maximum absorption—if you experience stomach discomfort, take it with a light meal.
4. Combine with vitamin C (orange juice, bell pepper) for 2-4x higher absorption of non-heme iron.
5. Avoid coffee, tea, and dairy within 1 hour of intake (absorption inhibitors).
6. Build up gradually and re-evaluate after 6-8 weeks with a new ferritin test.
7. For genetic predisposition to hemochromatosis: only under medical supervision, in accordance with the advice of the NVWA.

Myths and misconceptions about iron

Myth 1: "Spinach is an excellent source of iron—just look at Popeye."

Spinach contains about 3.6 mg of iron per 100g (cooked)—not bad, but not exceptional. Furthermore, spinach contains a lot of oxalates, which inhibit iron absorption. The Popeye myth stems from an error in a German food table from the 1930s—spinach's iron content was accidentally listed 10 times too high. The error has since been corrected, but the myth lives on.

Myth 2: "All iron causes stomach problems—you just have to get through it."

Classic iron supplements (sulfate) are indeed known for causing stomach issues. Modern forms—especially bisglycinate—are much better tolerated by most people. So, if you experience stomach problems, you don't have to "tough it out"—changing the form often solves the problem.

Myth 3: "Vegetarians and vegans automatically have an iron deficiency."

Not automatically. With careful nutrition (legumes, seeds, whole grains, dark vegetables) plus vitamin C with meals, a plant-based diet can provide sufficient iron. However, the absorption efficiency is lower, so more conscious attention is required than with a meat-containing diet. If in doubt: have ferritin levels measured.

Myth 4: "The more iron, the faster your deficiency will be corrected."

The body can only absorb a limited amount of iron at a time—and with daily high dosages, an increased hepcidin value can actually inhibit absorption. Recent research suggests better effectiveness of dosing every other day for adults, compared to daily high dosing.

Combining iron with other supplements

Iron works synergistically with various other nutrients. Commonly chosen combinations:

• Vitamin C: increases non-heme iron absorption 2-4x – essentially indispensable for vegans and vegetarians.
• Vitamin B12: relevant together for fatigue and plant-based diets (both potentially lower in vegans).
• Folic acid: together with B12 and iron, forms the basis for red blood cell production – especially important during pregnancy.
• Copper: plays a role in iron absorption and transport in the blood.
• Multivitamins for pregnant women: standardly combine iron, folic acid, B12, vitamin D.

Frequently Asked Questions

What is iron?

Iron (Fe) is an essential trace element, the main component of hemoglobin and myoglobin. Crucial for oxygen transport, energy, and immune function.

Which iron is best?

Bisglycinate: high absorption and stomach-friendly – the first choice for most. Heme iron: very high absorption (animal-based). Fumarate: for higher dosages. Sulfate is cheap but often causes stomach complaints.

What is the difference between heme iron and non-heme iron?

Heme iron (animal-based) is absorbed at 15-35%. Non-heme iron (plant-based and most supplements) is absorbed at 2-20%, highly dependent on what you eat with it.

How much iron per day?

EU-RI: 14 mg/day. Adult men and post-menopausal women: 8-9 mg. Menstruating women: 16-18 mg. Pregnant women: 27 mg. With proven deficiency, often higher by prescription.

When to take iron?

On an empty stomach for optimal absorption. If you experience stomach discomfort: with a light meal. Combine with vitamin C, avoid coffee/tea/dairy around intake.

Does iron help with fatigue?

EFSA recognizes that iron contributes to the reduction of tiredness and fatigue. The effect is greatest with a proven deficiency. Have ferritin levels checked before long-term supplementation.

What are iron deficiency symptoms?

Fatigue, shortness of breath on exertion, concentration problems, feeling cold, pale skin, brittle nails, hair loss, restless legs. No single symptom is definitive.

Can you take iron and coffee together?

No, coffee and tea contain tannins that inhibit iron absorption. Maintain at least 1 hour between coffee/tea and iron supplementation or iron-rich meals.

Iron for vegans – which one should I choose?

Bisglycinate or a combined formula with vitamin C. Plant-based capsule form. Conscious combination with vitamin C-rich foods doubles or quadruples absorption.

Does vitamin C help with iron absorption?

Yes. Vitamin C reduces non-heme iron (Fe³⁺ → Fe²⁺), leading to 2-4x better absorption in the intestine. Especially relevant for non-heme iron (plant-based + supplements).

Sources

• EFSA Regulation (EU) 432/2012 – iron claims.
• EFSA NDA Panel – Scientific Opinion on Dietary Reference Values for iron (2015).
• Stoffel NU. et al., "Iron absorption from oral iron supplements given on consecutive versus alternate days", Lancet Haematol (2017).
• Hurrell R. & Egli I., "Iron bioavailability and dietary reference values", Am J Clin Nutr (2010).
• WHO/FAO – Vitamin and Mineral Requirements in Human Nutrition (2nd ed., 2004).
• Health Council of the Netherlands – Dietary reference intakes for iron (2018).