Iron Deficiency in Women: Signs, Causes, Sources

Iron deficiency in women — at a glance, here are the most important points to walk away with before you read the deep dive below.

• Women need almost double the iron of men (14.8mg vs 8.7mg daily in the UK) because of menstrual losses, and around one in four women of reproductive age has iron-deficient stores. • Haem iron (meat, fish) absorbs at 15–35 per cent regardless of diet, while non-haem iron (plant foods, eggs) absorbs at only 2–20 per cent and is highly sensitive to what else is on the plate. • Vitamin C is the single most powerful absorption enhancer, capable of increasing non-haem iron uptake two to three times when paired in the same meal. • Tea and coffee are the biggest inhibitors, cutting absorption by up to 60–70 per cent — separate them from iron-rich meals by at least an hour. • Key symptoms include persistent fatigue, breathlessness, brain fog, hair loss, restless legs, and pica (craving ice or non-food items) — ask for a serum ferritin test, not just haemoglobin. • Vegetarians and vegans should aim for roughly 1.8 times the standard iron RNI to offset lower plant-iron bioavailability, using vitamin C pairing and cooking techniques like soaking and fermenting to boost absorption.

Iron requirements vary significantly across life stages and individual circumstances. The UK reference nutrient intake (RNI) for women aged 19 to 50 is 14.8mg per day — nearly twice the male recommendation of 8.7mg. This higher requirement accounts for menstrual losses, which average approximately 1mg of iron per day across the cycle but can be considerably higher in women with heavy periods (menorrhagia).

Women with heavy menstrual bleeding — defined as losing more than 80ml of blood per cycle — lose significantly more iron and may struggle to meet requirements through diet alone. If you experience periods that flood through protection, last longer than seven days, contain large clots, or leave you anaemic despite dietary effort, speak to your GP about both the gynaecological cause and the need for iron supplementation.

During pregnancy, iron requirements increase substantially — the recommended intake rises to approximately 27mg per day in the US and the NHS advises pregnant women to eat iron-rich foods regularly and take a supplement if levels fall. This reflects the expanding blood volume, the needs of the developing foetus, and the building of placental iron stores.

Post-menopausal women, whose menstrual losses have ceased, have iron requirements that drop to 8.7mg per day — comparable to men — and iron deficiency is less common in this group unless there is underlying gastrointestinal blood loss or malabsorption. Unexplained iron deficiency in a post-menopausal woman warrants investigation to rule out gastrointestinal bleeding.

Not all dietary iron is equal. Iron exists in two forms: haem iron (found in animal products) and non-haem iron (found in plant foods and eggs). Understanding the difference is essential for dietary planning, particularly for vegetarians and vegans.

Haem iron, derived from haemoglobin and myoglobin in meat and fish, is absorbed at a rate of approximately 15 to 35 per cent regardless of the body's iron status or the broader dietary context. It is absorbed via a dedicated transport pathway (HCP1) and is minimally affected by other dietary factors. The richest sources are red meat (beef, lamb, liver), dark poultry meat (chicken thighs), and shellfish (particularly oysters and clams). Organ meats such as chicken liver are extraordinarily iron-dense — a 100g serving of chicken liver provides around 13mg of iron alongside a full spectrum of other nutrients.

Non-haem iron, by contrast, is absorbed at a rate of only 2 to 20 per cent, and this absorption is highly sensitive to the dietary context. Enhancers and inhibitors in the same meal can dramatically alter how much iron actually reaches the bloodstream. Non-haem iron must first be converted from its oxidised ferric form (Fe³⁺) to its reduced ferrous form (Fe²⁺) before it can be absorbed — a process facilitated by stomach acid and vitamin C.

The best plant sources of non-haem iron include lentils (3.3mg per 100g cooked), chickpeas (2.9mg), tofu (2.7mg), edamame (2.3mg), spinach (2.7mg cooked), fortified breakfast cereals (often 8–14mg per serving), pumpkin seeds (8.8mg per 100g), quinoa (1.5mg), dried apricots (3.4mg), and dark chocolate (6.3mg per 100g). For vegetarians and vegans, the UK's National Diet and Nutrition Survey recommends consuming around 1.8 times the standard iron RNI to compensate for the lower bioavailability of plant iron.

Dietary iron absorption is not fixed — it is dynamically regulated by the body's iron status and profoundly influenced by what you eat alongside iron-rich foods. Strategically pairing iron sources with absorption enhancers, and separating them from inhibitors, can meaningfully increase the iron your body actually uses.

The most powerful absorption enhancer is vitamin C (ascorbic acid). Vitamin C converts non-haem iron from its poorly absorbed ferric form to the more soluble ferrous form, and simultaneously counteracts the effects of inhibitors such as phytates. Studies show that consuming as little as 50mg of vitamin C (roughly half a red pepper or a small glass of fresh orange juice) with a plant iron source can increase absorption by two to three times. Practical pairings: squeeze lemon juice on lentil soup, add bell peppers to a tofu stir-fry, eat a kiwi alongside fortified cereal, or serve chickpea curry with a tomato-based sauce.

Tannins in tea and coffee are among the most potent inhibitors of non-haem iron absorption. A cup of tea consumed with a meal can reduce iron absorption by 60 to 70 per cent; coffee by 40 per cent. The advice for those with low iron is to separate tea and coffee from iron-rich meals by at least one hour — ideally drinking them between meals rather than with them.

Phytates, found in wholegrains, legumes, and seeds, bind to iron and form insoluble complexes that cannot be absorbed. Soaking legumes before cooking, sprouting grains and seeds, and choosing fermented products (sourdough bread, fermented soy) all reduce phytate content and improve iron bioavailability significantly.

Calcium competes with iron for absorption — both use similar transport pathways. Consuming large quantities of dairy or calcium supplements with iron-rich meals reduces absorption. This is worth noting for those taking both iron and calcium supplements — they should be taken at separate times of day.

Iron deficiency occurs on a spectrum, from depleted iron stores (low ferritin but normal haemoglobin) through iron-deficient erythropoiesis (impaired red blood cell production) to frank iron deficiency anaemia. Symptoms can appear at any stage, even before anaemia is detectable on a standard blood count.

The classic symptoms of iron deficiency include persistent fatigue and weakness — often disproportionate to exertion — breathlessness on mild activity, heart palpitations, pale skin and mucous membranes, cold hands and feet, frequent headaches, difficulty concentrating (often described as 'brain fog'), and poor short-term memory. More specific signs include a sore or smooth tongue (glossitis), cracked corners of the mouth (angular cheilitis), brittle or spoon-shaped nails (koilonychia), and unusual food cravings such as ice, clay, or dirt (pica) — the latter being a recognised symptom of severe deficiency.

Hair loss is a particularly distressing symptom for many women. Iron is essential for the cell division that drives hair follicle activity. When stores are depleted, the body prioritises iron for vital functions and hair growth is depressed, often resulting in diffuse thinning across the scalp rather than patchy loss.

Restless legs syndrome — an uncomfortable urge to move the legs, particularly at rest or during sleep — is strongly associated with iron deficiency and often responds dramatically to iron repletion.

If you suspect iron deficiency, ask your GP for a full blood count and serum ferritin test. Ferritin below 30 micrograms per litre is generally considered deficient for functional purposes, and many symptoms improve significantly when ferritin is raised above 50 micrograms per litre. Supplementation with ferrous sulphate, ferrous fumarate, or ferrous gluconate is the standard treatment — typically taken on alternate days on an empty stomach with vitamin C to enhance absorption.

Putting iron nutrition into practice is about building meals where multiple iron sources appear alongside absorption enhancers. Here are some practical, everyday meal ideas that maximise dietary iron:

Breakfast: Fortified porridge oats topped with pumpkin seeds, dried apricots, and a glass of fresh orange juice is an excellent iron-rich start to the day. Alternatively, two eggs on sourdough toast (fermentation reduces phytates) with a side of spinach sautéed in olive oil provides haem iron from eggs and non-haem from spinach.

Lunch: A lentil and tomato soup (the tomatoes provide vitamin C, the lentils provide iron) with wholegrain bread, followed by a kiwi fruit. Or a quinoa bowl with chickpeas, roasted red peppers (high in vitamin C), cucumber, and tahini dressing — tahini is made from sesame seeds and provides additional iron alongside calcium.

Dinner: A beef stir-fry with broccoli, pak choi, and bell peppers — the haem iron from beef is highly bioavailable, and the vegetables provide vitamin C. Alternatively, a tofu and spinach curry with tomatoes and lemon — avoiding tea or coffee afterwards allows maximal iron absorption.

Snacks: A small handful of pumpkin seeds, a couple of squares of dark chocolate (at least 70 per cent cocoa), or hummus (made from chickpeas) with crudités all contribute meaningful iron between meals.

For women who are vegetarian or vegan, consciously including an iron source and a vitamin C source at every meal — and separating tea and coffee from meals — makes a significant cumulative difference to daily iron intake and absorption.

The guidance in this article draws on peer-reviewed nutrition and food-science literature as well as guidance from major public-health bodies. Key reference sources we have consulted while writing and updating this piece include:

• Harvard T.H. Chan School of Public Health, *The Nutrition Source*, 2024. • U.S. National Institutes of Health (NIH), Office of Dietary Supplements, fact sheets, 2024. • World Health Organization (WHO), Healthy Diet fact sheet, 2024. • Cochrane Database of Systematic Reviews — relevant systematic reviews, 2020–2024. • British Dietetic Association (BDA) Food Fact Sheets, 2024.

These references are provided so that motivated readers can verify claims and explore the underlying evidence directly. Where a specific trial, meta-analysis, or named author is referenced in the body of the article, that citation takes precedence over the general sources listed here. The article is reviewed periodically against newly published evidence and updated when meaningful new findings emerge.