Iron is needed to form the haem part of haemoglobin, the substance which carries oxygen around the body. Iron is mainly carried in the blood when bound to a protein called transferrin. Prolonged iron deficiency will lead to anaemia, symptoms of which include fatigue, pallor, breathlessness on exertion, feeling dizzy on standing, mood changes and depression. A chronically low iron level is also associated with hair loss, brittle nails, Plummer-Vinson syndrome (painful mucous membrane covering the tongue, mouth and throat) and a weakened immune system.
Causes of iron deficiency
- Bleeding (including excessive menstrual bleeding)
- Recent surgery or trauma
- Bleeding from the GI tract (ulcers or cancer of the gullet, stomach, bowel)
- Bleeding from nose, throat or lungs
- Poor diet
- Substances (in diet or drugs) interfering with iron absorption
- Malabsorption syndromes (Crohn’s disease, bowel surgery)
- Prolonged fever
Treatment of iron deficiency
Before any treatment can begin, there needs to be a definitive diagnosis of the underlying cause for iron deficiency, particularly in non-menstruating females and men. This typically involves a blood test measuring iron and other vitamin levels such as vitamin B12 and folate. If there is a definite and unexplained iron deficiency, patients are generally required to have an endoscopy and colonoscopy to exclude cancer of the gut. Once an iron deficiency has been diagnosed, it can be treated with iron supplements in the form of ferrous sulphate or gluconate tablets, although there are concerns with long-term iron supplementation (see below). Dietary measures can help restore iron levels or prevent recurrence after initial treatment.
Food sources of iron
Mild iron deficiency can be prevented or corrected by eating iron-rich foods. Because iron is a requirement for most plants and animals, a wide range of foods contain iron. Good sources of dietary iron include:
- Liver and liver pate
- Red meat, poultry, game
- Lentils, beans, chickpeas, black-eyed peas and other pulses
- Fish, particularly tinned sardines, tuna, swordfish and salmon
- Leafy green vegetables such as kale
- Green cruciferous vegetable such as broccoli and Brussel sprouts
- Tofu, fortified bread and breakfast cereals
Iron from different foods is absorbed and processed differently by the body. For instance, iron in meat (haem iron source) is more easily broken down and absorbed than iron from grains and vegetables (“non-haem” iron source). Minerals and chemicals in one type of food may also inhibit absorption of iron from another type of food when eaten at the same time.
The following are known to improve iron absorption and are recommended to those with a diagnosed deficiency:
Vitamin C – reduces the effect of phytic acid and enhances the absorption of iron
Probiotics (e.g. lactobacilli) – can create a more favourable PH and environment for oxalic acid excretion, increasing iron absorption
Conversely, there are a number of substances which can impair iron absorption, namely:
Oxalates – these form insoluble complexes which bind iron in the gut before it can be absorbed. Foods rich in oxalates include spinach, Swiss chard, fat hen, sorrel, rhubarb, buckwheat, quinoa and star fruit
Phytic acid – forms insoluble complexes which bind iron in the gut before it can be absorbed. Phytic acid is used as a preservative with E number E391
Cadmium – encourages the transformation of vitamin C into oxalic acid, reducing iron absorption. This can be a problem for people exposed to high levels of cadmium through diet, workplace conditions or smoking
Caution with Iron supplements
Because free iron is needed for bacteria to grow, there is a theory that iron supplementation can increase free iron bioavailability and, consequently, bacterial growth. Therefore, it may be sensible to stop iron supplements in the presence of a systemic bacterial infection.
In summary, if you are iron deficient consider consuming red meat once or twice a week and ensuring a higher intake of dark fish, dark green vegetables and beans. Avoid intake of oxalate-rich foods such as spinach, quinoa or buckwheat, and consider adding live yoghurts, probiotics and foods containing vitamin C to your diet.