Dietary Iron Guide

What's the difference between Haem and Non-Haem Iron?

Two forms of dietary iron with very different absorption: haem iron (from animal products): well absorbed (15-35%). Sources: red meat, poultry, fish, eggs (limited). Non-haem iron (from plant sources): poorly absorbed (2-20%). Sources: legumes, whole grains, dark leafy greens, fortified foods, nuts and seeds. The same 5mg iron: from beef provides ~1mg absorbed iron. From spinach provides ~0.5mg absorbed. Implications: vegetarians and vegans need approximately 1.8 times more iron from their diet to compensate for the lower absorption rate of non-haem iron sources compared to meat.

What do I need to know about Iron Deficiency Anaemia?

Most common nutritional deficiency in the UK and worldwide. NHS data: 23% of UK women aged 19-64 have iron deficiency. Up to 50% of pregnant women. 3-7% of UK men. Symptoms: fatigue (most common). Pale skin. Shortness of breath. Cold hands and feet. Brittle nails. Restless legs syndrome. Hair loss. Difficult concentration. Risk groups: menstruating women (especially heavy periods). Pregnant women (target 27mg/day). Vegetarians and vegans. Endurance athletes (mechanical haemolysis, sweat losses). Anaemia can only be confirmed with a blood test — in the US, HealthLabs.com offers walk-in iron and ferritin panel testing without needing to book a GP appointment first.

What should I know about Maximising Absorption?

Iron absorption enhancers (take with iron-rich foods): vitamin C — single most important enhancer. 100mg vitamin C (orange, pepper, kiwi, broccoli) can quadruple non-haem iron absorption. Cook in iron pans (cast iron) — small amount of iron transfers to food. Iron absorption inhibitors (separate from iron meals by 1-2 hours): tea and coffee — tannins bind iron, reduce absorption by 50-90%. Calcium supplements and dairy — compete with iron absorption. Phytates (whole grains, legumes) — bind iron.

What do I need to know about Supplementation?

When dietary iron is insufficient: ferrous sulphate (200mg = 65mg elemental iron): standard NHS prescription. Effective but causes GI side effects in 20% (constipation, nausea, dark stools). Ferrous fumarate: similar absorption, often better tolerated. Iron bisglycinate (chelated iron): newer form. Better tolerated, fewer GI effects. Less elemental iron per tablet but better absorbed. Liquid iron supplements, such as Floradix and Spatone, are gentler but lower dose — useful for sensitive stomachs but slower to correct a significant deficiency.

Not medical advice. This calculator is for general information and education only. Figures are estimates and may not reflect your circumstances. For decisions, consult your GP or a qualified healthcare professional. See our editorial standards.

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