Chelated Iron vs Heme Iron: Comparing Absorption and Stomach Tolerance

Fatigue and iron deficiency: the 2018 meta-analysis

A systematic review of randomised trials in adults with normal haemoglobin but low ferritin found that oral iron supplementation significantly reduced self-reported fatigue, with a standardised mean difference of -0.38. It points to a measurable effect at the "latent" deficiency stage, before anaemia develops.

Source:Efficacy of iron supplementation on fatigue in non-anaemic iron-deficient adults: SR of RCTs (2018)

Three types side by side

• Inorganic salts (ferrous sulfate and similar): cheapest, roughly 5-10% absorption, most reported stomach upset and constipation
• Amino acid chelates (bisglycinate and similar): organic form, generally better tolerated and somewhat better absorbed
• Heme iron: animal-derived, roughly 15-35% absorption, gentler on the stomach, not suitable for vegetarians
• Coatings: enteric or slow-release coatings reduce stomach irritation but shift where absorption happens

Searching this database for "iron", "heme" or "bisglycinate" lets you compare elemental iron content and coating materials across products.

Compare iron products in the databaseFilter by amount, dosage form and brand

This article summarises general health information. It is not intended to diagnose or treat any condition, or to guide changes to medication. If you have a medical condition, are pregnant or breastfeeding, or take prescription medicines, talk to a physician or pharmacist.