Iron deficiency is the most common nutritional deficiency in the world. It disproportionately affects women of reproductive age - particularly women with heavy menstrual bleeding - and within that group, African and Black women are at particularly high risk.
What concerns me most in clinical practice is not the deficiency itself - it is treatable - but how long it goes unrecognised. I regularly see women who have been running on empty for two, three, five years. Who have accepted their fatigue, their breathlessness on exertion, their inability to concentrate, their intolerance of cold as simply the way they are. Who have been told their blood tests are fine - when what has been tested is haemoglobin, which can remain within the normal reference range long after iron stores are critically depleted.
Why African women are particularly at risk
Heavy menstrual bleeding: The most common cause of iron deficiency in pre-menopausal women. Fibroids and endometriosis - both more prevalent and more severe in Black women - cause significant blood loss every menstrual cycle. Blood contains iron. Losing 80ml or more per period (clinically defined as heavy menstrual bleeding) can deplete iron stores faster than dietary intake can replenish them.
Dietary factors: Traditional African diets can be lower in haem iron (from red meat - the form absorbed most efficiently) and higher in plant foods. Plant iron (non-haem iron) is absorbed at 2-10% efficiency compared to 20-30% for haem iron. The phytate content of staple foods including beans, grains, and some vegetables further inhibits non-haem iron absorption.
Tea: One of the most common and most underappreciated causes of reduced iron absorption. Tannins in tea bind to iron in the gut and prevent its absorption. Taking tea with meals or within an hour of eating can reduce iron absorption by 60-70%. This is particularly relevant in communities where tea is drunk with every meal.
Pregnancy: Pregnancy substantially increases iron requirements. Women with marginal iron stores before pregnancy commonly become significantly iron-deficient during it.
Vitamin C deficiency: Vitamin C dramatically increases non-haem iron absorption by converting it to a more absorbable form. Diets low in fresh fruit and vegetables may limit this absorption-enhancing effect.
Symptoms - the full picture
Iron deficiency produces symptoms at every stage, not just when anaemia develops.
Fatigue: Often the most prominent symptom. Disproportionate to activity levels. Not resolved by sleep. Iron is required for cellular energy production in every tissue in the body.
Breathlessness on exertion: Climbing stairs, walking briskly, or exercising causes breathlessness that feels out of proportion to fitness level.
Poor concentration and brain fog: Iron is required for optimal neurotransmitter synthesis, particularly dopamine and serotonin pathways. Cognitive effects of iron deficiency are well documented.
Hair loss: Diffuse shedding, often most noticeable as increased hair in the shower or on the hairbrush. Iron is essential for hair follicle cell division and keratinisation.
Brittle nails: Including koilonychia (spoon-shaped nails) in severe deficiency.
Pica: Craving for non-food substances - most commonly ice, but also chalk, clay, or starch. Not imagined. Neurological manifestation of iron deficiency.
Cold intolerance: Feeling cold disproportionately, cold hands and feet even in warm environments.
Restless legs syndrome: An urge to move the legs at rest, particularly in the evening, associated with uncomfortable sensations. Iron deficiency is a major reversible cause.
Reduced immune function: Iron is essential for normal immune cell function.
The ferritin problem - the test your GP may be missing
Ferritin is the protein that stores iron in the body. It is the earliest and most sensitive marker of iron depletion - it falls significantly before haemoglobin begins to drop.
Many GPs request a full blood count to check for anaemia and consider the investigation complete if haemoglobin is normal. This misses iron deficiency without anaemia entirely - a stage that is symptomatic and treatable but invisible to a blood count.
Ask your GP specifically for a serum ferritin test.
Reference ranges for ferritin vary between laboratories and are often set at a minimum threshold (above 10-15 mcg/L in many labs). However, symptoms of iron deficiency are common at ferritin levels well above this - most women with fatigue and iron-related symptoms do not feel well until ferritin is above 70-100 mcg/L.
Case study: Blessing running on empty for three years
Blessing, 34, a healthcare assistant from Nigeria based in Sheffield, came to me for a routine health check. She mentioned chronic fatigue she had accepted as normal. She was sleeping 8-9 hours per night and waking unrefreshed. She had significant hair shedding over the past two years. She was cold most of the time.
A previous full blood count (done by another GP 18 months earlier) had shown haemoglobin of 11.8 g/dL - flagged as mildly low but not acted upon. Ferritin had never been checked.
I checked her ferritin. It was 6 mcg/L - severely depleted.
She had been symptomatic for at least three years.
I prescribed ferrous sulphate 200mg twice daily and referred her for investigation of the cause - she had heavy periods and an ultrasound revealed a 4cm uterine fibroid.
At her six-week review: "I feel like a completely different person. The fatigue I had accepted as just part of my life - it is almost gone. I did not realise how bad I felt until I started feeling better."
Her ferritin at 12 weeks: 48 mcg/L - improved but not yet optimal. She continued supplementation.
Treatment - iron supplementation that actually works
First-line: Ferrous sulphate 200mg: Standard NHS treatment. Contains approximately 65mg of elemental iron per tablet. Take once or twice daily.
Alternate-day dosing: Research published in Blood (Moretti et al., 2015) demonstrated that taking iron on alternate days produces greater absorption than daily dosing, because hepcidin (a hormone that inhibits iron absorption) rises for 24 hours after an iron dose and blocks absorption of the next daily dose. Alternate-day dosing allows hepcidin to clear before the next dose.
With vitamin C: Taking a glass of orange juice or a vitamin C supplement with your iron tablet increases absorption by 30-40%.
Away from inhibitors: Take iron at least 1-2 hours away from tea, coffee, calcium supplements, antacids, and dairy products. These all inhibit iron absorption.
Intravenous iron: For people who cannot tolerate oral iron, or whose absorption is significantly impaired (e.g. inflammatory bowel disease, coeliac disease), IV iron infusion provides rapid and complete iron repletion. A single infusion can restore iron stores completely within 1-2 weeks. Available on the NHS in appropriate circumstances.
Monitor and continue: Recheck ferritin at 3 months. Continue supplementation until ferritin is above 70 mcg/L. Address the underlying cause of iron loss simultaneously.
Sources: WHO - Iron Deficiency Anaemia: Assessment, Prevention and Control 2001; Camaschella C, NEJM 2015 (iron deficiency anaemia review); Moretti D et al, Blood 2015 (alternate-day dosing); British Society of Gastroenterology - UK guidelines on iron deficiency anaemia 2021; Goddard AF et al, Gut 2011; Tolkien Z et al, PLOS ONE 2015 (ferrous sulphate side effects).
