Iron Deficiency, Fatigue, Low Mood and Cognition
Iron is essential for oxygen transport, energy metabolism, muscle function and several brain-related processes. When iron status is low, people may experience tiredness, weakness, poor concentration, breathlessness, palpitations, dizziness and reduced resilience. These symptoms can easily overlap with depression, anxiety, burnout and stress.
This lesson explains the relationship between iron deficiency, fatigue, mood and cognition, with attention to ferritin, anaemia, menstruation, pregnancy, vegetarian diets, supplementation safety and when medical assessment is needed.
On this page
- What iron does
- Iron deficiency and iron deficiency anaemia
- Why it overlaps with mental health symptoms
- Ferritin and iron stores
- Who is at greater risk?
- Menstruation, pregnancy and blood loss
- Food sources of iron
- Iron absorption and meal planning
- Iron supplements and safety
- Red flags and referral points
- A practical framework
- Reflection questions
What Iron Does
Iron is a mineral required for growth, development, oxygen transport, muscle metabolism and several cellular functions. It is a key part of haemoglobin, the protein in red blood cells that carries oxygen around the body, and myoglobin, which helps supply oxygen to muscles.
The NIH Office of Dietary Supplements explains that the body uses iron to make haemoglobin in red blood cells and myoglobin in muscle, and also needs iron to make some hormones. NIH Office of Dietary Supplements
Key idea
Iron deficiency can make ordinary life feel harder because the body’s oxygen transport and energy systems are affected. This can look like poor motivation, low mood, anxiety-like symptoms or burnout, even when the underlying issue is partly physical.
Iron Deficiency and Iron Deficiency Anaemia
Iron deficiency means the body’s iron supply is too low. Iron deficiency anaemia occurs when iron deficiency has affected red blood cell production enough to reduce haemoglobin. A person can have low iron stores before they become anaemic, which is why symptoms may begin before standard anaemia is obvious.
The NHS states that iron deficiency anaemia is caused by lack of iron, often because of blood loss or pregnancy, and is treated with iron tablets and by eating iron-rich foods. NHS
| Term | Meaning | Why it matters |
|---|---|---|
| Low iron intake | The diet may not supply enough absorbable iron. | Can occur with restricted diets, low food intake or poorly planned vegetarian and vegan diets. |
| Low ferritin | Iron stores are low. | Symptoms may occur even before anaemia is clearly established. |
| Iron deficiency anaemia | Iron deficiency has affected haemoglobin and red blood cell function. | Can cause tiredness, breathlessness, palpitations, pallor and reduced capacity. |
| Iron overload | Too much iron accumulates in the body. | Iron supplements should not be taken casually or indefinitely without clinical reason. |
Why It Overlaps With Mental Health Symptoms
Iron deficiency can produce symptoms that resemble or worsen mental health difficulties. Tiredness, brain fog, low motivation, irritability, low mood and reduced exercise tolerance can be mistaken for depression, anxiety, stress, laziness or poor discipline.
NHS Inform lists common symptoms of iron deficiency anaemia including tiredness and lack of energy, shortness of breath, noticeable heartbeats and pale complexion. NHS Inform
Possible iron-related symptoms
Physical and cognitive signs
- Tiredness and lack of energy.
- Shortness of breath.
- Palpitations.
- Dizziness or light-headedness.
- Poor concentration or brain fog.
- Reduced exercise tolerance.
Mental health overlap
Common misreadings
- “I am depressed because I cannot get going.”
- “I am anxious because my heart races.”
- “I am burned out because I am always exhausted.”
- “I am lazy because simple tasks feel difficult.”
- “I cannot focus, so something is wrong with my mind.”
Clinical framing
Iron deficiency does not explain all fatigue, low mood or anxiety. However, where symptoms suggest possible anaemia or low iron stores, physical assessment should be encouraged rather than assuming the issue is purely psychological.
Ferritin and Iron Stores
Ferritin is a protein that stores iron. A ferritin blood test is commonly used to assess iron stores. Low ferritin can indicate depleted iron stores, even before anaemia is severe or obvious.
NICE Clinical Knowledge Summaries states that, in all people, a serum ferritin level of less than 30 micrograms per litre confirms a diagnosis of iron deficiency, while also noting that ferritin levels can be difficult to interpret in inflammatory states. NICE CKS
Why ferritin matters
- Haemoglobin shows whether anaemia is present.
- Ferritin gives information about iron stores.
- A person may feel unwell with low stores before severe anaemia is identified.
- Ferritin can be raised by inflammation, infection or liver disease, which may complicate interpretation.
- Test results should be interpreted by a healthcare professional alongside symptoms and medical history.
Mental health practitioners should not diagnose from ferritin values, but they can recognise that “normal haemoglobin” does not always mean iron status is optimal or irrelevant.
Who Is at Greater Risk?
Iron deficiency can occur when intake is low, absorption is poor, requirements are increased or blood loss is ongoing. It is especially important to consider causes, because treating low iron without finding the reason may miss a significant medical problem.
Higher need
Life stage and physiology
- Menstruation, especially heavy periods.
- Pregnancy.
- Adolescence and growth.
- Endurance training or high physical demands.
Lower intake
Dietary patterns
- Restricted eating or low overall intake.
- Vegetarian or vegan diets without planning.
- Low intake of iron-rich foods.
- Food insecurity.
Loss or absorption
Medical factors
- Gastrointestinal bleeding.
- Coeliac disease or inflammatory bowel disease.
- Recent surgery or blood donation.
- Some medications and chronic illness.
The NIH identifies groups at risk of iron inadequacy including pregnant people, infants and young children, people with heavy menstrual bleeding, frequent blood donors, people with cancer, people with gastrointestinal disorders or surgery, and people with heart failure. NIH Office of Dietary Supplements
Menstruation, Pregnancy and Blood Loss
Blood loss is one of the most common reasons for iron deficiency. Heavy menstrual bleeding can gradually deplete iron stores and lead to anaemia. Pregnancy increases iron requirements, which is why fatigue during pregnancy should not be dismissed as simply “normal”.
In adult men and postmenopausal women, iron deficiency anaemia requires careful assessment because gastrointestinal blood loss can be an important cause. The same is true for anyone with rectal bleeding, black stools, unexplained weight loss, persistent abdominal symptoms or recurrent anaemia.
| Situation | Why it matters | Practical response |
|---|---|---|
| Heavy periods | Ongoing blood loss can deplete iron stores. | Medical review may be needed, especially if fatigue, dizziness or flooding occurs. |
| Pregnancy | Iron requirements rise, and anaemia can affect wellbeing. | Follow antenatal screening and supplement advice from midwife or doctor. |
| Postmenopausal bleeding | Bleeding after menopause is not expected. | Prompt medical assessment is required. |
| Rectal bleeding or black stools | May indicate gastrointestinal blood loss. | Seek medical advice rather than self-treating with iron. |
| Frequent blood donation | Can lower iron stores over time. | Review donation frequency, diet and ferritin if symptoms develop. |
Do not ignore the cause
Iron deficiency is not only a diet issue. Blood loss, malabsorption and medical disease must be considered, especially in men, postmenopausal women and anyone with gastrointestinal symptoms or unexplained weight loss.
Food Sources of Iron
Iron in food is found in two main forms: haem iron and non-haem iron. Haem iron is found in animal foods and is generally more easily absorbed. Non-haem iron is found in plant foods and fortified foods, and absorption is more affected by other dietary factors.
| Type of iron | Food sources | Absorption note |
|---|---|---|
| Haem iron | Red meat, poultry, fish and seafood. | Generally more easily absorbed by the body. |
| Non-haem iron | Beans, lentils, chickpeas, tofu, nuts, seeds, wholegrains, fortified cereals and leafy greens. | Absorption is improved by vitamin C and reduced by some inhibitors. |
Animal sources
- Lean red meat.
- Poultry.
- Sardines and other fish.
- Shellfish.
- Liver, though this is not suitable in pregnancy due to vitamin A content.
Plant sources
- Lentils and beans.
- Chickpeas and hummus.
- Tofu and tempeh.
- Pumpkin seeds and sesame seeds.
- Spinach, kale and other greens.
Fortified sources
- Fortified breakfast cereals.
- Fortified breads or flour products where applicable.
- Some meat alternatives.
- Some fortified plant-based foods.
- Check labels, as products vary.
The NHS lists iron-rich foods including liver, meat, beans, nuts, dried fruit, fortified breakfast cereals and soya bean flour. NHS
Iron Absorption and Meal Planning
Iron intake is not the only issue. Absorption also matters. Vitamin C can improve absorption of non-haem iron, while tea, coffee and calcium-rich foods can reduce absorption when taken at the same time as iron-rich meals or supplements.
Can support absorption
Pair iron with vitamin C
- Beans with tomatoes.
- Lentil soup with peppers.
- Fortified cereal with berries.
- Hummus with salad and lemon juice.
- Tofu stir-fry with broccoli.
Can reduce absorption
Separate from iron when needed
- Tea and coffee with meals.
- Calcium supplements.
- Large amounts of dairy taken with iron supplements.
- Some antacid medication.
- High-bran foods taken with supplements.
Simple food combinations
- Chilli made with beans, tomatoes and peppers.
- Lentil dhal with spinach and lemon.
- Scrambled tofu with peppers and wholegrain toast.
- Sardines on toast with tomato salad.
- Fortified cereal with berries, with tea or coffee taken later.
Iron Supplements and Safety
Iron supplements can be effective when iron deficiency is confirmed or strongly suspected by a clinician. However, iron should not be taken casually, indefinitely or at high dose without medical reason. Too much iron can be harmful, and iron tablets can cause side effects such as constipation, nausea, abdominal discomfort and dark stools.
NICE CKS covers treatment with oral iron supplements and management of underlying causes of iron deficiency anaemia. NICE CKS
Supplement safety
- Do not self-prescribe iron long term without testing or clinical advice.
- Iron overdose is dangerous, especially for children. Store supplements securely.
- Iron can interact with some medicines, including levothyroxine and some antibiotics.
- Side effects may be improved by changing timing, formulation or dose under advice.
- Iron deficiency should trigger consideration of the cause, not only replacement.
The NIH notes that acute high-dose iron ingestion can be corrosive to the gastrointestinal tract and can cause serious systemic toxicity, especially in children. NIH Office of Dietary Supplements
Red Flags and Referral Points
Iron-related symptoms may be mild and gradual, but some presentations require prompt medical assessment. This is especially important where blood loss, pregnancy, severe symptoms or neurological-like symptoms are present.
Refer for medical assessment where there is:
- Persistent fatigue with breathlessness, palpitations, dizziness or fainting.
- Heavy menstrual bleeding, flooding, clots or bleeding between periods.
- Pregnancy with significant fatigue, dizziness or breathlessness.
- Rectal bleeding, black stools, vomiting blood or unexplained abdominal symptoms.
- Unexplained weight loss, loss of appetite or night sweats.
- Iron deficiency in men or postmenopausal women.
- Repeated iron deficiency despite supplementation.
- Restricted eating, rapid weight loss or suspected eating disorder.
The NHS advises seeing a GP if symptoms of iron deficiency anaemia are present, with a blood test used to confirm diagnosis. NHS
A Practical Framework for Mental Health Work
Mental health practitioners do not need to diagnose iron deficiency, but they should recognise when it may be contributing to distress, fatigue or cognitive difficulty.
| Step | Question | Practical response |
|---|---|---|
| 1. Ask about symptoms | Is there persistent fatigue, breathlessness, dizziness, palpitations or poor concentration? | Consider whether physical assessment is needed. |
| 2. Ask about blood loss | Are periods heavy? Is there rectal bleeding, black stools or recent blood donation? | Refer for medical assessment where blood loss is possible. |
| 3. Ask about diet | Is intake low, restricted, vegetarian, vegan or lacking iron-rich foods? | Support iron-rich meals and vitamin C pairing. |
| 4. Ask about testing | Has haemoglobin and ferritin been checked? | Encourage GP review where symptoms or risks are present. |
| 5. Avoid overreach | Is the person also depressed, anxious or traumatised? | Iron assessment can support care but should not replace mental health treatment. |
Example practitioner wording
“The tiredness and brain fog you describe may be part of depression or stress, but they can also overlap with iron deficiency. Given the heavy periods and palpitations, it would be sensible to ask your GP about blood tests, including iron stores.”
“I would not suggest taking iron indefinitely without checking the cause, because iron deficiency can sometimes be due to blood loss or absorption problems.”
Eating Disorders, Restriction and Iron
Iron deficiency may occur where a person is eating too little overall or avoiding many iron-rich foods. However, nutrition advice must be handled carefully if eating disorder risk is present. Encouraging rigid tracking, high-control dieting or fear-based food rules may worsen the problem.
Clinical caution
Where there is rapid weight loss, food fear, purging, laxative misuse, compulsive exercise, amenorrhoea or severe restriction, refer for appropriate eating disorder assessment and care. Iron status may still need assessment, but it should be part of wider clinical support.
Reflection Questions
For students, practitioners or course participants:
- Why can iron deficiency be mistaken for depression, anxiety or burnout?
- What is the difference between low ferritin and iron deficiency anaemia?
- Which groups are at greater risk of iron deficiency?
- Why should iron deficiency prompt questions about blood loss?
- What safety issues should be considered before someone starts iron supplements?
Key Takeaway
Iron deficiency can contribute to fatigue, brain fog, poor concentration, low mood, dizziness, palpitations and reduced resilience. These symptoms can overlap with mental health difficulties, so iron status should be considered where risk factors are present. The safest approach is to identify the cause, use appropriate testing such as haemoglobin and ferritin, support iron-rich eating, and avoid unsupervised long-term supplementation.
References and Further Reading
- NHS. Iron deficiency anaemia.
- NHS Inform. Iron deficiency anaemia: symptoms and treatment.
- NICE Clinical Knowledge Summaries. Anaemia: iron deficiency.
- NICE Clinical Knowledge Summaries. Investigations for iron deficiency anaemia.
- NICE Clinical Knowledge Summaries. Management of iron deficiency anaemia.
- NIH Office of Dietary Supplements. Iron: health professional fact sheet.