Does taking iron help, or is it actually a risk?

Pregnant women and people with iron-deficiency anaemia benefit the most from iron supplementation. Daily iron raises haemoglobin levels and reduces the risk of anaemia in infants, school-age children, and both pregnant and non-pregnant women. This has been demonstrated in a large overview of 75 systematic reviews. Preventive supplementation during pregnancy is therefore recommended for all pregnant women, regardless of region.

If you have an iron deficiency without anaemia, supplementation can reduce your fatigue. Four randomised trials involving more than 700 participants found a small to moderate effect on self-reported fatigue. However, iron has no demonstrable effect on athletic performance in that situation: maximum oxygen uptake did not change.

A real drawback is that iron tablets frequently cause gastrointestinal complaints, such as nausea and an unpleasant feeling in the stomach. This sometimes leads people to take them inconsistently, which makes the treatment less effective. For pregnant women who experience daily side effects, taking them less frequently can help, but that in turn raises the risk of anaemia around the time of delivery. It is therefore a trade-off.

For some groups the situation is especially complex. People with chronic kidney disease need iron supplementation, but overly generous use carries risks. In vegan children the risk of iron deficiency is greater, because plant-based iron is absorbed less efficiently. And for premature infants, European guidelines recommend supplementation until at least one year after the original due date. In all these cases, medical supervision is essential.

What you should never do without good reason is take extra iron if you have no deficiency. Healthy adults with adequate iron status gain no benefit from it. Moreover, too little is known about the risks of prolonged excess iron during pregnancy to formulate sound guidelines. Have your iron levels measured before starting supplements.