Iron deficiency is the most common nutritional deficiency worldwide, and women are especially vulnerable. Menstruation, pregnancy and breastfeeding all increase iron requirements. Yet early iron deficiency often goes unrecognised because symptoms develop gradually and are easily attributed to something else.
Why women face a higher risk
Menstrual blood loss is the primary reason. The average woman loses 30-40 ml of blood per period, but with heavy periods this can exceed 80 ml. This difference has a significant impact on iron stores over time. Pregnancy increases blood volume by 50%, demanding a rise in daily iron intake from 15 mg to 27 mg. Breastfeeding, puberty and intensive exercise further increase requirements.
Diet also plays a role. If you eat little or no meat, you consume less easily absorbed iron. This need not be a problem, but it requires awareness and planning.
Symptoms: more than just tiredness
Iron deficiency develops gradually and many women adapt to the symptoms without realising how much better they could feel. Common signs include persistent fatigue, paleness of skin and gums, dizziness when standing, palpitations during mild exertion, concentration problems, hair loss, brittle nails, cold extremities, restless legs at night and, in severe cases, pica (cravings for ice or non-food items).
Ferritin versus haemoglobin: know the difference
Haemoglobin is a late indicator: it only drops once iron stores are significantly depleted, meaning you are already in the anaemia stage. Ferritin is far more sensitive. It reflects your iron stores and declines long before haemoglobin falls. You can feel tired and unfocused while your haemoglobin is still within range. This is called latent iron deficiency: empty stores without anaemia, but already with symptoms.
The stages of iron deficiency: (1) depletion of iron stores with falling ferritin, (2) latent deficiency with symptoms but normal haemoglobin, (3) iron-deficiency anaemia with both ferritin and haemoglobin low. A ferritin below 30 µg/L warrants attention, even if haemoglobin is normal.
Transferrin and transferrin saturation
Transferrin is the transport protein that carries iron through your blood. It rises when iron is scarce, like sending more trucks on the road that are running empty. Transferrin saturation shows what percentage of transferrin is actually loaded with iron. A saturation below 20% confirms insufficient circulating iron. Together with ferritin and haemoglobin, these values form the complete iron profile.
Iron-rich foods: haem versus non-haem
Haem iron from animal sources (red meat, poultry, fish, shellfish) has an absorption rate of 15-35% regardless of what else you eat. Non-haem iron from plant sources (legumes, dark leafy greens, nuts, seeds, whole grains) has a 2-20% absorption rate heavily influenced by other nutrients in the meal.
Good plant-based sources include lentils, chickpeas, spinach, kale, pumpkin seeds, sesame seeds, quinoa, oats, tofu, tempeh and dried apricots.
Improving absorption and avoiding inhibitors
Boosters: vitamin C is the most powerful enhancer, increasing non-haem iron absorption by a factor of 2-6. Add bell pepper to salads, squeeze lemon over lentil soup or drink orange juice with meals. Meat and fish in the same meal also improve non-haem iron absorption. Fermented foods like sourdough bread contain less phytic acid, making iron more available.
Inhibitors: coffee and tea tannins reduce absorption by 50-90%, so drink them at least one hour before or two hours after iron-rich meals. Calcium in dairy competes with iron, so avoid combining dairy with your most iron-rich meal. Phytic acid in whole grains and legumes can be reduced by soaking, sprouting and thorough cooking. Oxalates in spinach and rhubarb bind some iron; cooking reduces their effect.
Supplementation: when, which form and for how long
Iron supplements only make sense after a blood test confirms a deficiency. Blind supplementation is unwise because iron overload can damage the liver, heart and pancreas.
Iron bisglycinate is generally better tolerated than iron fumarate or sulphate, with fewer gastrointestinal side effects. Take it on an empty stomach with vitamin C for optimal absorption, or with a light meal if stomach issues occur. Recent research suggests alternate-day dosing may be equally effective and better tolerated. Replenishing stores typically takes three to six months. Do not stop early, even if symptoms improve. Retest ferritin after three months.
Vegetarians and vegans
Plant-based diets can provide sufficient iron, but the recommended daily intake for vegetarians is 1.8 times higher than for omnivores due to lower non-haem iron absorption. Always combine plant-based iron sources with vitamin C. Vary your sources between legumes, greens, nuts and grains. Soak legumes for at least eight hours before cooking. Consider using cast-iron cookware. Cook vegetables rather than eating them raw to reduce oxalates and phytic acid. Test your ferritin one to two times per year.
When to get tested
Consider an iron blood test if you experience persistent fatigue, paleness, palpitations during mild exertion, concentration problems, hair loss, heavy periods, are planning a pregnancy, follow a vegetarian or vegan diet, or do intensive endurance sports. Request a complete iron profile: ferritin, haemoglobin, iron and transferrin saturation for the most comprehensive assessment.
Frequently asked questions
How long does it take to replenish iron stores?
Haemoglobin usually improves within four to eight weeks of supplementation, bringing more energy and less paleness. Replenishing ferritin takes longer: expect three to six months depending on severity and dosage. Continue supplementation until ferritin reaches a healthy level, ideally above 50 µg/L, even if you feel better sooner.
Can you take too much iron?
Yes. Iron overload causes oxidative damage to the liver, heart and pancreas. In haemochromatosis, a hereditary condition affecting roughly 1 in 200 people of European descent, iron supplementation is dangerous. Always confirm a deficiency with a blood test before supplementing.
Which blood test measures iron best?
Ferritin is the most informative single marker. For the most complete picture, a full iron profile (ferritin, iron, haemoglobin and transferrin saturation) shows how much iron you have in stores, how much is circulating and how well it is being transported. This is particularly relevant when ferritin is borderline or previous supplementation did not produce expected results.
Author