Iron deficiency: symptoms, causes, and natural solutions

Unexplained fatigue, pallor, hair loss, shortness of breath during exertion… These very common symptoms are often blamed on stress or lack of sleep. However, an iron deficiency is frequently the culprit—and it affects millions of people in France without them even knowing.

📑 Table of Contents

1. Difference between iron deficiency and iron-deficiency anemia
2. Symptoms of iron deficiency: how to recognize them
3. Who is most at risk of iron deficiency?
4. Diagnosis: how to confirm an iron deficiency?
5. Diet and supplementation to restore iron reserves

🔬 Difference between iron deficiency and iron-deficiency anemia

Iron deficiency progresses through several successive stages, and it is important to understand this progression so as not to confuse two distinct realities.

📉 Iron deficiency (stages 1 and 2)

Iron deficiency refers to a state where the body's reserves are dwindling, without hemoglobin production being compromised yet. At stage 1, only iron stores (ferritin) drop. At stage 2, ferritin continues to fall and the saturation of transferrin—the iron transport protein—decreases. Symptoms at these stages can be subtle or absent, but diffuse fatigue, lower endurance, and mild cognitive issues may already appear.

It is during these early stages that nutritional intervention and supplementation are most effective in preventing further deterioration.

🔴 Iron-deficiency anemia (stage 3)

Iron-deficiency anemia occurs when the lack of iron is severe enough to compromise hemoglobin synthesis and red blood cell formation. The red blood cells become smaller (microcytosis) and less colored (hypochromia). It is at this stage that the classic symptoms of anemia appear in all their intensity: profound fatigue, palpitations, dyspnea, and pallor of the mucous membranes.

The World Health Organization (WHO) estimates that iron-deficiency anemia is the most widespread nutritional deficiency in the world, affecting approximately 1.62 billion people (WHO, 2008). In France, according to data from the Esteban study (Santé publique France, 2016), the prevalence of anemia remains significant in vulnerable groups, particularly women of childbearing age and the elderly.

😣 Symptoms of iron deficiency: how to recognize them

Iron deficiency manifests through a spectrum of symptoms that can vary in intensity depending on the stage of the deficiency and individual characteristics.

⚡ Fatigue and lack of energy

This is the most common symptom and often the first to appear. Iron contributes to normal energy metabolism and the reduction of fatigue (EU Regulation No. 432/2012). When iron stores are depleted, cell energy metabolism is disrupted, leading to a persistent feeling of fatigue that does not improve with rest.

😮‍💨 Shortness of breath and palpitations

Iron contributes to the normal transport of oxygen in the body via hemoglobin. When iron reserves are insufficient, the ability to transport oxygen decreases. The heart and lungs compensate by speeding up their rhythm, which causes shortness of breath during exertion and palpitations, particularly noticeable during activities that would normally have little impact.

💆 Cognitive symptoms and concentration difficulties

The brain is a high oxygen-consuming organ. A decrease in oxygen-carrying capacity affects cognitive functions: difficult concentration, memory lapses, irritability, and even mild depression. These symptoms, often attributed to stress or overwork, may actually indicate an iron deficiency, especially in women of childbearing age.

💅 Physical manifestations: skin, hair, nails

Iron deficiency can also be seen in physical appearance:

• Pallor: particularly visible in the mucous membranes (inside the eyelids, gums), the palms of the hands, and the nail beds.
• Hair loss: the hair follicle is a rapidly renewing tissue that is very sensitive to iron availability. A deficiency can lead to diffuse hair loss (telogen effluvium).
• Brittle or spoon-shaped nails (koilonychia): a classic but later sign of severe deficiency.
• Sore tongue (glossitis) and cracked corners of the mouth (angular cheilitis): mucosal signs of severe deficiency.

🍦 Pica and atypical food cravings

Some people with iron deficiency develop a compulsive attraction to non-food substances like crushed ice (pagophagia), dirt (geophagia), or chalk. This phenomenon, called pica, is a recognized symptom of iron deficiency, the mechanism of which is not fully understood.

👥 Who is most at risk of iron deficiency?

👩‍🦰 Women of childbearing age

Menstruation is the primary cause of iron deficiency in non-menopausal women. Women with heavy periods (menorrhagia) are particularly at risk. Recommended dietary allowances (RDA) in France for women aged 15 to 50 are 16 mg of iron per day, a recommendation difficult to achieve solely through diet, especially in the case of a low-meat diet.

🤰 Pregnant women

Pregnancy significantly increases iron requirements: fetal development, expansion of the mother's blood volume, and the buildup of the newborn's hepatic stores. RDA during pregnancy reaches 25 to 35 mg of iron per day depending on the trimester. Iron deficiency during pregnancy is associated with risks for the mother (increased fatigue, reduced immunity) and the baby (low birth weight, premature birth).

🌿 Vegetarians and vegans

A vegetarian or vegan diet relies exclusively on non-heme iron, which has a low absorption rate (2-20%) and is strongly influenced by the composition of the meal. Phytates in whole grains and legumes, oxalates in spinach, tannins in tea, and polyphenols in coffee further reduce this absorption. Vegans have iron needs that are 1.8 times higher than general recommendations, according to reference nutritional data.

🏃 Intensive athletes

Athletes who practice endurance sports lose iron through multiple pathways: sweating, gastrointestinal micro-bleeding, and mechanical hemolysis during repeated impacts (especially in running). Athlete's anemia is a well-documented clinical reality, particularly in female long-distance runners and triathletes.

👴 The elderly

Aging is often accompanied by a reduction in food intake, lower gastric acidity (which reduces non-heme iron absorption), and sometimes occult bleeding linked to common digestive pathologies (ulcers, colorectal cancers). Iron deficiency in the elderly is often multifactorial.

🩺 Diagnosis: how to confirm an iron deficiency?

🔬 Key biological tests

Confirming an iron deficiency relies on blood tests:

• Serum ferritin: this is the reference marker for iron stores. Ferritin below 30 µg/L indicates depletion of iron stores, even in the absence of anemia. A result below 12 µg/L confirms a severe deficiency.
• Hemoglobin: measured in a complete blood count (CBC), it only drops in the case of established anemia (stage 3). Hemoglobin below 12 g/dL for women and 13 g/dL for men defines anemia according to WHO criteria.
• Transferrin saturation: a reflection of available circulating iron, it drops before anemia is established.
• MCV (Mean Corpuscular Volume): a lowered MCV (microcytosis) is characteristic of advanced stages of iron deficiency.

It is recommended to consult a doctor to prescribe these tests and interpret the results within their overall clinical context.

🥗 Diet and supplementation to restore iron reserves

🥩 Optimizing your dietary iron intake

To increase iron intake through diet:

• Sources of heme iron (better absorbed, 15-35%): red meat, poultry, fish, seafood (oysters, mussels).
• Sources of non-heme iron (plant-based): legumes (lentils, chickpeas, white beans), tofu, fortified cereals, pumpkin seeds, spinach.
• Promote absorption: consume foods rich in vitamin C with the same meal as non-heme iron sources (bell peppers, citrus fruits, kiwi, broccoli).
• Reduce inhibitors: do not drink tea or coffee within 2 hours of iron-rich meals; limit dairy products with the same meal as plant-based iron sources.

💊 Iron bisglycinate supplementation: the gentle and effective solution

When diet alone is not enough to cover needs or restore depleted reserves, supplementation becomes essential. Iron bisglycinate is particularly recommended as a dietary supplement for several reasons:

• Superior absorption to conventional ferrous salts, even when taken with meals.
• Excellent digestive tolerance: significantly fewer instances of nausea, constipation, and abdominal cramps than ferrous sulfate.
• Compatibility with a vegetarian or vegan lifestyle.

✅ Our iron bisglycinate at Pure Lab Nutrition: a gentle and highly bioavailable formula to help reduce fatigue, support normal red blood cell formation and energy metabolism.

👉 Discover our entire range of supplements here.

✅ In summary

1️⃣ Iron deficiency evolves in three stages: depletion of reserves, functional deficiency, and then iron-deficiency anemia with a drop in hemoglobin.
2️⃣ The most frequent symptoms are fatigue, shortness of breath, pallor, hair loss, and concentration issues.
3️⃣ The most exposed populations are women of childbearing age, pregnant women, vegetarians, athletes, and the elderly.
4️⃣ Diagnosis relies on measuring serum ferritin, hemoglobin, and transferrin saturation—to be done with your doctor.

Pure Lab Nutrition — The art of nourishing your well-being.

Scientific sources:

1. World Health Organization (2008). Worldwide prevalence of anaemia 1993-2005. WHO Global Database on Anaemia. Geneva: WHO Press.
2. Santé publique France (2019). Étude Esteban 2014-2016 — Volet nutrition : apports nutritionnels et indicateurs du statut en fer dans la population adulte française.
3. Camaschella C. (2015). Iron-deficiency anemia. New England Journal of Medicine, 372(19):1832-43.
4. Pawlak R, Berger J, Hines I. (2016). Iron Status of Vegetarian Adults: A Review of Literature. American Journal of Lifestyle Medicine, 12(6):486-498.
5. Commission Regulation (EU) No 432/2012 of 16 May 2012 establishing a list of permitted health claims made on foods. Official Journal of the European Union, L 136/1.