Iron deficiency is the most common nutritional deficiency worldwide and one of the most frequently missed causes of fatigue in the UK. It is particularly prevalent in women of reproductive age, teenage girls, pregnant women, and vegetarians/vegans. The good news: it is straightforward to diagnose with a blood test and highly treatable with iron supplementation.
Why Iron Matters
Iron has two primary roles in the body. Haemoglobin: iron is the central component of haemoglobin, the protein in red blood cells that carries oxygen to every cell. Iron deficiency anaemia — insufficient haemoglobin — impairs oxygen delivery throughout the body. Cellular function: iron is required for mitochondrial electron transport chain function (ATP production), immune cell proliferation, neurotransmitter synthesis, and thyroid hormone metabolism. This is why iron deficiency causes symptoms even before haemoglobin falls enough to diagnose anaemia — depleted iron stores (low ferritin) affect cellular function before red blood cells are affected.
Common Causes
Insufficient dietary intake: haem iron (from meat and fish) is 3–4× more bioavailable than non-haem iron (from plants, eggs, fortified foods). Vegetarians and vegans need approximately 1.8× the iron intake of meat-eaters. Increased demand: heavy menstrual bleeding (the most common cause in premenopausal women), pregnancy (iron demand increases substantially, particularly in the 2nd and 3rd trimesters), and rapid growth in adolescence. Malabsorption: coeliac disease, inflammatory bowel disease, previous gastric surgery, helicobacter pylori infection. Chronic blood loss: GI bleeding (from NSAIDs, peptic ulcer, bowel cancer — iron deficiency anaemia in a man or postmenopausal woman always requires GI investigation to exclude occult bleeding). Donations and phlebotomy: regular blood donors are at risk.
Recognising Iron Deficiency
Classic anaemia symptoms: fatigue and reduced exercise tolerance, pallor, breathlessness on exertion, palpitations, headaches. Pre-anaemia deficiency signs (low ferritin without anaemia): fatigue, poor concentration and brain fog, restless legs, hair loss (telogen effluvium — particularly common with ferritin below 30–40 ng/mL), brittle nails, reduced immune function, cold intolerance, low mood. Severe iron deficiency: pica (craving non-food items — ice, clay), angular stomatitis, glossitis, koilonychia (spoon-shaped nails).
Testing and Treatment
Testing: full blood count (FBC) for haemoglobin and red cell indices; serum ferritin for iron stores. Normal ferritin range varies by lab but ≥30 ng/mL is generally considered minimum for functional adequacy; ≥70–100 ng/mL is optimal for women with symptoms. Treatment: iron-rich diet plus oral iron supplementation. Ferrous sulphate 200mg (65mg elemental iron) is first-line — take on an empty stomach with Vitamin C for maximum absorption; expect black stools. If poorly tolerated: ferrous gluconate (lower elemental iron, fewer GI side effects). Duration: typically 3 months after haemoglobin normalises to replenish stores.
Frequently Asked Questions About Iron
Why does my iron keep being low despite supplementing?
Persistent iron deficiency despite supplementation suggests: inadequate dose, poor absorption (take on empty stomach with vitamin C, avoid with tea/coffee/calcium within 2 hours), ongoing blood loss exceeding replacement (heavy periods may need gynaecological assessment), undiagnosed malabsorption (coeliac disease — worth testing if not done), or H. pylori infection (impairs iron absorption). GP review is appropriate for persistent deficiency.
Can I get enough iron from a plant-based diet?
Yes, with attention to both quantity and absorption. Best plant sources: lentils (6mg per 100g cooked), tofu (3mg per 100g), quinoa (2mg per 100g), fortified cereals, dark leafy greens, pumpkin seeds. Always consume with vitamin C (inhibits phytate iron inhibition). Avoid tea, coffee, and calcium-rich foods within 1–2 hours of iron-rich meals (all reduce absorption).
Browse iron supplements at Huncoat Pharmacy. Related: B12 Deficiency, Vegan Nutrition.
At Huncoat Pharmacy: IV iron infusion service, Browse iron supplements, Anaemia home testing kit.