Iron Deficiency in Women and Vegetarians: A Practical Clinical Guide

Iron deficiency is the most prevalent micronutrient deficiency in the world and a leading cause of anaemia in the UK.[1] In women of reproductive age the prevalence of iron-deficiency anaemia is around 9–12% in higher-income countries; iron deficiency without overt anaemia is much higher still.[2] The clients I see most often in this category are menstruating women — particularly those with heavy periods, recent pregnancy, or a vegetarian or vegan pattern of eating — alongside endurance athletes and adolescents going through growth spurts.

There are two numbers worth understanding on a blood test. Haemoglobin (Hb) tells you whether you currently have anaemia (in adult women, the WHO threshold is <120 g/L; in adult men, <130 g/L).[3] Serum ferritin tells you about your iron stores — and stores can be low long before haemoglobin drops, which is why people often feel exhausted while their "blood count is fine". NICE Clinical Knowledge Summaries recognise a serum ferritin <30 µg/L as consistent with iron deficiency in most adults, with a higher threshold (around <100 µg/L) used in the presence of inflammation or chronic disease.[4]

Symptoms are easy to dismiss because they are non-specific: persistent fatigue, breathlessness on stairs you used to take in your stride, brittle hair or nails, restless legs at night, an unusual craving to chew ice or other non-foods (pica), and reduced exercise tolerance. If several of these are creeping in, ask your GP for a full blood count plus serum ferritin — not just haemoglobin alone.

On the dietary side, iron comes in two forms. Haem iron — found in red meat, poultry, and fish — is absorbed at around 15–35%. Non-haem iron — found in pulses, dark leafy greens, fortified breakfast cereals, tofu, nuts and seeds — is absorbed at around 2–20%, with the percentage strongly affected by what you eat alongside it.[5] For vegetarians and vegans, the practical implication is not "you must eat meat"; it is "the way you combine plant-based iron sources matters a lot."

Three combinations consistently improve plant-iron absorption. Vitamin C alongside the meal — peppers, citrus, kiwi, tomatoes — can increase non-haem iron uptake severalfold. A small amount of haem iron in the same meal increases absorption from non-haem foods. And, perhaps most importantly, separating tea and coffee from iron-rich meals by 60–90 minutes prevents tannins and polyphenols from blunting absorption — this single change shifts ferritin trajectory in many of my clients.

When supplementation is indicated — usually when ferritin is well below threshold or anaemia is established — the current best evidence supports alternate-day rather than daily dosing. Stoffel and colleagues showed that taking 60–120 mg of elemental iron every other day produces higher cumulative iron absorption than daily dosing, with fewer gastrointestinal side effects, because daily dosing increases hepcidin and shuts down the next day's uptake.[6] This finding has changed routine UK practice; if your GP has prescribed daily ferrous sulphate and you are getting nausea or constipation, ask about alternate-day dosing.

A final word on heavy menstrual bleeding. If your periods last longer than seven days, you flood through pads or tampons hourly, or you pass clots larger than a 10p coin, the iron deficiency is downstream of the bleeding. NICE recommends investigation of menorrhagia in primary care — treating the iron alone without addressing the underlying cause is a leaky bucket.[7] Dietetic support and medical workup go hand in hand here.

If your ferritin has been low for a while and dietary tweaks alone are not getting you back up, it is worth working through a proper plan together. Bring your most recent FBC and ferritin results and a typical week of eating to the discovery call.