What is anemia?
Anemia happens when your blood cannot carry enough oxygen to meet your body's needs. This is usually because you have too few red blood cells, or because those cells contain too little haemoglobin — the iron-rich protein that binds oxygen. With less oxygen reaching your tissues, you can feel tired, weak and short of breath.
Anemia is not a single disease but a sign that something is affecting your blood. It ranges from mild and easily corrected to severe, and identifying the underlying cause is an important part of treating it effectively.
Symptoms of anemia
Mild anemia may cause few or no symptoms. As it becomes more pronounced, common signs include:
- •Tiredness and a lack of energy
- •Shortness of breath, especially on exertion
- •Pale skin
- •Heart palpitations or a noticeably fast heartbeat
- •Dizziness or lightheadedness
- •Headaches
- •Cold hands and feet
- •Brittle nails or hair loss, with long-standing iron deficiency
What causes anemia?
There are many causes, but they generally fall into three groups: not making enough red blood cells, losing blood, or destroying red blood cells too quickly. Iron-deficiency anemia, the most common type worldwide, occurs when the body lacks enough iron to make haemoglobin.
Frequent causes include:
- •Iron deficiency — from blood loss, low dietary iron, or poor absorption
- •Heavy menstrual periods
- •Pregnancy, which increases iron demands
- •Deficiency of vitamin B12 or folate
- •Slow internal bleeding, for example from the stomach or bowel
- •Chronic diseases, such as kidney disease
- •Inherited conditions, such as sickle cell disease or thalassaemia
How it's diagnosed and treated
Anemia is diagnosed with a blood test called a full blood count, which measures your haemoglobin and red blood cells. Further tests, such as checking your iron, B12 or folate levels, help identify the cause. Because anemia can occasionally be a sign of internal bleeding or another underlying problem, finding the cause is as important as correcting the anemia itself.
Treatment depends on the cause. Iron-deficiency anemia is often treated with iron-rich foods and iron supplements. B12 or folate deficiency is treated by replacing those nutrients. Where anemia results from blood loss or an underlying condition, treating that source is essential. Most people respond well once the cause is addressed.
Iron-rich foods and diet
Since iron deficiency is the most common cause of anemia, diet plays an important role in both prevention and recovery. There are two types of dietary iron: haem iron, found in animal foods and absorbed more easily, and non-haem iron, found in plant foods and absorbed less readily. Including a variety of both helps maintain healthy iron levels.
Good sources of haem iron include red meat, poultry and fish. Plant sources of non-haem iron include beans, lentils, tofu, dark leafy greens such as spinach, fortified cereals, nuts and seeds, and dried fruit like apricots. An important tip is that vitamin C improves the absorption of non-haem iron, so pairing plant iron sources with vitamin-C-rich foods — such as citrus fruit, peppers or tomatoes — boosts how much iron your body takes up.
Some substances reduce iron absorption, including the tannins in tea and coffee and the calcium in dairy, so it can help to avoid drinking tea or coffee with iron-rich meals. For people diagnosed with iron-deficiency anemia, diet alone is often not enough to correct it quickly, and supplements prescribed by a doctor are usually needed alongside dietary improvements.
Anemia in pregnancy and specific groups
Certain groups are more prone to anemia and may need particular attention. Pregnancy substantially increases the body's iron requirements, as iron is needed to support the growing baby and the increase in the mother's blood volume. Mild anemia is common in pregnancy, which is why iron levels are routinely checked and supplements are often recommended; significant anemia in pregnancy should always be managed with medical guidance.
Women with heavy menstrual periods are also at higher risk, as regular blood loss depletes iron stores over time. Infants, young children and adolescents have higher iron needs during periods of rapid growth. Older adults can develop anemia for several reasons, including poorer diet, reduced absorption, or underlying conditions, and anemia in this group always warrants investigation of the cause.
Because the right treatment depends on both the type and the cause of anemia, anyone in these groups who develops symptoms such as persistent tiredness, breathlessness or pallor should see a doctor rather than simply starting supplements, which could mask an underlying problem that needs attention.
The different types of anemia
Although iron-deficiency anemia is by far the most common, anemia is actually a group of conditions with different underlying causes, and knowing the type matters because it guides treatment. Broadly, the causes fall into three groups: not producing enough healthy red blood cells, losing blood, or destroying red blood cells faster than they can be replaced.
Beyond iron deficiency, vitamin-deficiency anemia results from a lack of vitamin B12 or folate, both needed to make red blood cells, and is treated by replacing those nutrients. Anemia of chronic disease can accompany long-term conditions such as kidney disease, inflammatory disorders or cancer. Inherited anemias, such as sickle cell disease and thalassaemia, are caused by genetic differences in haemoglobin and need specialist care.
Some anemias are caused by the body destroying its own red blood cells too quickly, known as haemolytic anemia. Because the treatment differs so much between these types — from simple iron or vitamin supplements to managing an underlying disease or specialist care for inherited conditions — diagnosing the specific type and cause is an essential part of treating anemia properly, which is why blood tests look beyond just the haemoglobin level.