Iron: Understanding the world’s #1 micronutrient deficiency
Iron is essential to human health, playing a crucial role in oxygen transport throughout the body and supporting the synthesis of amino acids, collagen, hormones, neurotransmitters, and bone marrow. Despite being abundant on earth, iron deficiency remains the most common micronutrient shortfall globally. Iron demands significantly increase during growth phases—particularly infancy, childhood, adolescence—and are especially critical for menstruating women due to regular blood loss. During pregnancy, increased blood volume elevates iron needs dramatically, with deficiency linked to anaemia, compromised maternal immunity, birth complications, and developmental issues in infants.
Recommended iron intake
Iron needs vary depending on age, sex, and life stage, rising notably during adolescence, pregnancy, and breastfeeding. Requirements jump at puberty, with recommendations increasing from 8 mg/day to 15 mg/day, due to higher blood volume and menstrual blood loss (females). Pregnancy further increases these requirements to support maternal and foetal health, while lactation demands iron to support infant neurodevelopment, providing long-lasting health benefits for the child.
Understanding iron excess and toxicity
Excessive iron intake can lead to toxic accumulation in organs such as the liver, heart, and joints, causing severe oxidative damage. Symptoms of iron toxicity include abdominal pain, vomiting, diarrhoea, lethargy, and fatigue. Iron toxicity often results from supplement overdoses but can also arise from haemochromatosis—a genetic condition leading to uncontrolled iron absorption. Chronic fatigue and joint problems are common symptoms reported by patients with haemochromatosis. Other contributing factors include excessive alcohol consumption and repeated blood transfusions. Chronic iron overload can escalate to severe complications, including haemorrhage, acidosis, coma, and liver failure.
Recognising and preventing iron deficiency
Iron deficiency remains the world’s leading micronutrient deficiency, disproportionately affecting pregnant women, infants, children, adolescents, and vegetarians or semi-vegetarians. Deficiency manifests as reduced blood iron levels, fatigue, weakness, headaches, pale skin, and decreased motivation. Adolescents commonly experience concentration difficulties and tiredness linked to iron deficiency. Even when dietary iron requirements are met, certain dietary components—such as phytates, polyphenols, calcium, and peptides from partially digested proteins—can hinder iron absorption, emphasising the importance of mindful dietary planning.
Dietary sources of iron
Dietary iron is categorised as haem iron (animal sources) and non-haem iron (plant and animal sources). Haem iron boasts higher bioavailability, with an average absorption rate of 18% compared to 10% for non-haem iron. To maximise iron intake, diets should incorporate iron-rich foods, recognising the differences in bioavailability to effectively address iron needs across all life stages.
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