Iron Explained Simply

1. What Is Iron?

Iron is a trace element. The body needs it above all for the red blood pigment, which transports oxygen in the blood. It also needs it for the muscle pigment and for many enzymes. Iron is stored as ferritin. The ferritin value in the blood shows how full the iron stores are.

2. Where Is It Found, and What Is It Made From?

Well-absorbable iron is found in meat, liver and fish. Plant iron is found in pulses, wholegrain, seeds and green vegetables. The body absorbs plant iron less well. Together with vitamin C it works better. Preparations for oral intake contain either ferrous iron or ferric iron in complexes. For severe deficiency or intolerance, iron is available as an infusion.

3. What Does Iron Do? What Research Shows

Iron Deficiency and Anaemia

In iron deficiency and anaemia, iron infusions raised the red blood pigment more than a sham treatment or oral iron 515161718. Oral iron lowered iron deficiency and anaemia in pregnancy 213545. Around operations and during chemotherapy, iron infusions reduced the need for blood transfusions 152024252627. In anaemia due to cancer, iron together with blood-forming agents improved the blood count more than these agents alone 33.

Fatigue and Physical Performance

In heart failure with iron deficiency, exercise capacity improved more with iron infusions than with a sham treatment 523. After childbirth, fatigue decreased more with iron infusions than with oral iron 16. Mostly people with iron deficiency and underlying diseases were studied. The studies say nothing about healthy people without iron deficiency.

Heart Failure

In heart failure with iron deficiency, iron infusions reduced hospital admissions due to heart failure in several reviews 567101112. The classification of complaints according to NYHA class also improved in several reviews 51019. For death from cardiovascular disease, the results were inconsistent 671319. In acute heart failure, one review found no difference 18. The benefit in acute heart failure as well as the best amount and the rhythm of administration remain open.

Infants and Children

Birth weight differed neither between iron infusion and oral iron 2940 nor between iron supplementation and a sham treatment 35. Preterm births and small-for-gestational-age newborns were also not less frequent 35. In fully breastfed healthy infants, weight and head circumference increased somewhat less with iron 28. In children with iron deficiency without anaemia, the authors of a study report better growth with liposomal iron 42. It remains open for which groups and administration rhythms a benefit nevertheless exists.

Sleep and Restless Legs

In adults with restless legs, iron, taken orally or as an infusion, improved the complaints more than a sham treatment 3032. Quality of life also improved 3032. For self-rated sleep quality, the studies found differing results 3032. In children with autism and sleep disorders, iron showed hardly any effect on sleep 22. It remains open which iron compound, which amount and which rhythm are most favourable.

Concentration and Cognitive Development

In children with iron deficiency without anaemia, liposomal iron improved developmental scores more than a sham treatment 42. In fully breastfed infants, iron did not change the developmental score at twelve months 28. In women with iron deficiency anaemia in pregnancy, better iron values went hand in hand with better mood 44. Weekly iron with folic acid lowered mental complaints in adolescent girls more than no supplementation 43.

Pregnancy

In healthy pregnant women, low-dose iron bisglycinate led to fewer gastrointestinal complaints and less often to black stool than fumarate or sulfate 41. The highest tested amount of fumarate led more often to constipation than lower amounts 41. For bleeding, transfusions and quality of life, no differences were shown 1735. The certainty of evidence is overall low. Mainly oral iron, infusions and enriched foods were studied.

Other Outcomes

In dialysis patients, high-dose iron as an infusion did not lead to more infections than low-dose iron 37. Before heart surgery, an iron infusion did not reduce transfusions and infections in people without anaemia 46.

4. How Was Iron Taken in the Studies?

Iron is available as a tablet or capsule to swallow and as an infusion into the vein. Iron compounds such as sulfate, fumarate and bisglycinate for oral intake, iron in complexes, liposomal iron, enriched foods and infusions were studied. The studies compared partly infusion with oral intake, partly different amounts or rhythms. Mixed preparations with folic acid, zinc or other micronutrients were often used.

5. Is Iron Safe? Side Effects in the Studies

Several reviews found no more serious adverse effects with iron infusions than with control 101114. With oral iron, dark stool was common 39.

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