Iron Deficiency & Fatigue in Women

This is the most important thing to understand about iron. Your body stores iron as ferritin and uses it to build haemoglobin. When intake or absorption fails to keep pace with losses, stores draw down first. Haemoglobin — the number on a standard complete blood count — is defended until stores are nearly gone. So there is a long window, often years, in which ferritin is low, you feel genuinely awful, and your complete blood count reads entirely normal. This is called iron deficiency without anaemia, and it is extremely common in women. During that window you can have: • Fatigue that sleep does not fix • Breathlessness on stairs, and palpitations • Hair shedding, months after stores fell • Poor concentration and brain fog • Restless legs at night • Low mood and irritability • Unusual cold intolerance • Craving ice — which is fairly specific to iron deficiency and worth mentioning Many laboratories only flag ferritin below about 15 ng/mL, but symptoms commonly appear well above that. A result inside the reference range is not the same as an optimal result. The practical takeaway: ask for a ferritin level by name. Do not accept "your blood count is normal" as an answer to persistent fatigue.

Repleting iron without finding the cause means doing it again in a year — and occasionally means missing something serious. In menstruating women, the usual answer is menstrual blood loss, and it is frequently under-recognised because most women have no reference point for what counts as heavy. Soaking a pad or tampon hourly for several hours, clots larger than a coin, bleeding beyond seven days or waking to change protection all qualify. If that is the cause, the bleeding itself needs addressing. Other common causes: • Inadequate dietary intake, particularly on vegetarian and vegan diets without deliberate planning • Impaired absorption — coeliac disease, gastritis, H. pylori infection, or low stomach acid • Long-term proton pump inhibitor use, which reduces the acid needed to absorb iron • Pregnancy, breastfeeding, and closely spaced pregnancies • Chronic inflammation, which raises hepcidin and blocks both absorption and release • Gastrointestinal blood loss from ulcers, polyps or colorectal pathology That last one matters. Unexplained iron deficiency in a post-menopausal woman, or in anyone without an obvious source of loss, warrants gastrointestinal evaluation rather than supplementation alone.

Most people who say they cannot tolerate iron have been given the wrong form on the wrong schedule. Form: ferrous sulphate is cheap and poorly tolerated, causing nausea and constipation in a large share of people. Iron bisglycinate is considerably gentler at comparable elemental doses. Schedule: this is the part that surprises people. Alternate-day dosing is often better absorbed than daily dosing. Taking iron raises hepcidin for roughly the next 24 hours, which then blocks absorption of the following day's dose. Dosing every other day works with that rhythm instead of against it — and halves your gastrointestinal exposure. Co-factors and inhibitors: • Take with vitamin C, which meaningfully improves absorption • Avoid taking it with calcium, coffee or tea, all of which inhibit absorption • Take away from thyroid medication, which iron interferes with Timeline: energy commonly improves within three to six weeks. Rebuilding ferritin takes three to six months of consistent supplementation, sometimes longer if losses continue. Hair regrowth lags furthest — six months or more — because the hair cycle is slow. The most common mistake is stopping as soon as you feel better. Feeling better means haemoglobin recovered; it does not mean stores are refilled. That is why so many women are deficient again within the year. Retest at around three months and continue until ferritin is genuinely restored, not merely over the laboratory cut-off.

Haem iron, from animal foods, is absorbed considerably more efficiently than non-haem iron from plants. That does not make a plant-based diet unworkable, but it does mean it needs planning. Good non-haem sources include lentils, beans, tofu, tempeh, pumpkin seeds, fortified grains and dark leafy greens. What matters as much as the source is what surrounds it: • Pair iron-rich foods with vitamin C — peppers, citrus, tomatoes — which substantially improves non-haem absorption • Soak, sprout or ferment legumes and grains to reduce phytates, which bind iron • Keep tea and coffee away from meals; the polyphenols are potent absorption inhibitors • Avoid taking calcium supplements alongside iron-containing meals A well-planned plant-based diet can maintain iron status. What it often cannot do is keep pace with heavy menstrual losses — so if you are vegetarian or vegan and bleeding heavily, testing rather than assuming is the sensible approach.