Having enough iron in our bodies is essential for good health. Iron deficiency is the most common nutritional deficiency in the world. Low levels can be due to not taking in enough iron from your diet, not absorbing enough into your system or losing too much from your body. Treatment will depend on the cause.
What is iron and why do we need it?
Iron is a metal found widely in nature but it is also essential to a healthy body. It is used by the body to make haemoglobin which carries oxygen around the body in red blood cells and myoglobin which delivers oxygen to our muscles. It is also important for the healthy growth of hair, skin and nails. Experts are increasingly discovering how important iron is for the normal transmission of signals in the brain as well.
We get iron in our diet in two forms:
- Haem iron, which is found in meat and fish.
- Non-haem iron, which is found in vegetables and grains.
What causes iron deficiency?
You become short of iron for one (or a combination of) the following reasons:
- You need more than your diet is providing.
- You are losing more than your diet is providing.
- You are not absorbing enough even though there is enough in your diet.
Your intake is not enough for your needs
This can happen if:
- You are growing fast - so, for example, this is common in children and young people. Breast milk contains iron in a form that is extremely easy for a baby to absorb. However, once the baby is older than 4-6 months, breast milk simply doesn't contain enough iron for them anymore.
- You are pregnant so need more iron than normal, as you have to make the cells for the developing infant.
- Your diet doesn't contain enough iron. This is more likely to be the case if you don't eat any meat. However, vegetarians and vegans who have a well-balanced diet should be able to avoid iron deficiency. Even in meat eaters, the majority of iron in the diet comes from non-meat sources.
- You diet frequently to try to lose weight.
You are losing iron from your body
For example, this can happen if:
- You are having periods, particularly if they are heavy.
- You have digestive problems such as acid reflux or a stomach ulcer.
- You have a disease that causes your gut (bowel) to become very inflamed, such as Crohn's disease or ulcerative colitis.
- You regularly take anti-inflammatory painkillers, such as ibuprofen.
- You have frequent nosebleeds (epistaxes) or bleed from piles (haemorrhoids).
- You have bleeding from your bowel that you can't see, such as is caused by colon cancer (although cancer usually also makes you anaemic).
- You have worms in your gut - for example, hookworms.
- You donate blood.
- You have blood in your urine.
- You have a skin condition that causes your skin to be shed much more than normal.
- You are en endurance athlete.
Your body isn't able to absorb iron properly from your gut
This can happen if:
- You eat or drink foods or beverages that interfere with the way iron is absorbed from your gut, such as phytates (found in high-fibre foods) and phenols (found in tea and coffee).
- Calcium (which is contained in some medicines) also interferes with the absorption of iron.
- You don't have enough acid in your stomach - for example, because you regularly take medicines to reduce stomach acid (such as medicines called proton pump inhibitors) or because you have had surgery to remove part of your stomach.
- You have coeliac disease.
What other problems affect how your body deals with iron?
Some diseases can make you short of iron because the way that the body uses iron and moves it about in the body is altered by the disease, such as:
What are the symptoms of iron deficiency?
The symptoms of iron deficiency may be very vague, particularly if isn't bad enough to have caused you to have developed iron-deficiency anaemia as well.
Some common symptoms are:
- Struggling to concentrate at work or college.
- Memory problems.
- Reduced ability to exercise.
- Hair losing its condition, and possibly hair loss.
- Nails becoming brittle and breaking or splitting easily. They may even change shape, becoming concave or spoon-shaped, or may develop ridges.
- Cuts and grazes taking a long time to heal.
- A sore tongue.
- Sores at the corners of your mouth.
- Restless legs syndrome.
- Infants with iron deficiency may not develop as quickly as normal.
- Pica syndrome: the craving or eating of substances not normally eaten, such as clay, chalk or coal.
When should I see a doctor?
Many of the symptoms of iron deficiency are also the symptoms of the busy, and sometimes stressful, lives we live. Tiredness and struggling to focus at work, for example, are very common and not usually due to iron deficiency. They usually just get better on their own after a week or two.
If you have had one or more of the symptoms listed above, for more than a few weeks, you should arrange to see a doctor or nurse. You can then have investigations carried out, which will include looking to see if iron deficiency is causing your symptoms. If you are short of iron, it is important to get medical advice.
How is iron deficiency diagnosed?
A blood test is taken to look for the levels of iron (ferritin) in your blood and to make sure that you aren't also anaemic. If you are short of iron, your ferritin level will usually be low. A full blood count (FBC) will also be taken. This looks at the number, size and colour of your red blood cells. If you have iron deficiency, your red blood cells will be smaller and paler than normal. If there are also not as many red blood cells as normal then you also have iron-deficiency anaemia.
Will I need any other tests?
Sometimes it isn't possible to be absolutely certain that you are iron-deficient from the results of these two blood tests. In that case other tests may be needed, such as:
- A blood film, in which blood is looked at down a microscope.
- Measurement of vitamin B12 and folate.
- Other tests of the body's iron stores - serum iron, transferrin (carries iron around the body), iron-binding capacity (IBC), for example.
- Bone marrow biopsy.
Occasionally a trial of iron treatment will be recommended and the tests then repeated after a few weeks.
Whether or not you need other tests will also depend on whether the reason for you being short of iron is obvious. For example, if you are a woman in your twenties with heavy periods, it is unlikely you will need any other tests to confirm the reason for you having iron deficiency (although you would, of course, benefit from treatment to help your periods). If, however, you are in your sixties and also have indigestion as well as iron deficiency, your doctor will want to make sure that you don't have a condition such as a stomach ulcer or oesophagitis. Therefore, you may need further tests to look for such conditions.
How is iron deficiency treated?
Iron deficiency is usually treated either by increasing the amount of iron in your diet or by taking a medicine with iron in it.
Which foods contain iron?
Haem iron is the form of iron most easily absorbed by the body and is found in meat and fish. Meat also improves the absorption of non-haem iron, which is found in vegetables. A well-balanced diet that contains some meat or fish should contain adequate iron for a healthy person - supplements should not be necessary.
If you do not eat meat or fish, it is even more important to ensure that you include some or all of the following food groups in your diet:
- Pulses: chickpeas, lentils, kidney beans, and soy beans, including tofu.
- Dark green leafy vegetables: cabbage, broccoli and kale. (Beware spinach and chard though, as they contain oxalic acid which is thought to interfere with iron absorption.)
- Cereals, such as breakfast cereals (may also have added iron).
- Grains: brown rice and wholemeal pasta.
- Dried fruit: especially apricots, raisins, dates and prunes.
- Nuts: cashews and almonds.
The following table shows some examples of the iron content of foods. It has been taken from the 'Iron Fact Sheet' produced by the United States National Institutes of Health, Office of Dietary Supplements:
|Food||Mg per serving||% daily value (DV)*|
|Breakfast cereal, fortified with 100% of the DV for iron, 1 serving||18||100|
|Oysters cooked with moist heat, 3 oz/85 g||8||44|
|White beans, canned, 1 cup/250 ml||8||44|
|Dark chocolate, 45-69% cocoa solids 3 oz/85 g||7||39|
|Beef liver, pan-fried, 3 oz/85 g||5||28|
|Lentils, boiled and drained, ½ cup/125 ml||3||17|
|Tofu, firm, ½ cup/125 ml||3||17|
|Kidney beans, canned, ½ cup/125 ml||2||11|
|Sardines. canned in oil, drained solids with bone, 3 oz/85 g||2||11|
|Chickpeas, boiled and drained, ½ cup/125 ml||2||11|
|Tomatoes, tinned, stewed, ½ cup/125 ml||2||11|
|Beef, braised, trimmed of fat, 3 oz/85 g||2||11|
|Potato, baked, flesh and skin, 1 medium potato||2||11|
|Cashew nuts, oil-roasted, 18 nuts (1 oz/28 g)||2||11|
|Green peas, boiled, ½ cup/125 ml||1||6|
|Chicken, roasted, meat and skin, 3 oz/85 g||1||6|
|Enriched white long-grain rice, boiled ½ cup/125 ml||1||6|
|Bread, wholewheat, 1 slice||1||6|
|Bread, white, 1 slice||1||6|
|Raisins, ¼ cup/60 ml||1||6|
|Spaghetti, wholewheat, cooked, 1 cup/250 ml||1||6|
|Tuna light, canned in water, 3 oz/75 g||1||6|
|Turkey roasted, breast meat and skin, 3 oz/75 g||1||6|
|Pistachio nuts, dry-roasted, 1 oz/28 g (about 50 nuts)||1||6|
|Broccoli, boiled, ½ cup/125 ml||1||6|
|Egg, hard boiled, 1 large||1||6|
|Brown rice, cooked, 1 cup/250 ml||1||6|
|Cheddar cheese, 1½ oz/45 g||0||0|
|Cantaloupe melon, diced, ½ cup/125 ml||0||0|
|Mushrooms, white, sliced and stir-fried, ½ cup/125 ml||0||0|
|Cottage cheese 2% fat, 1 cup/250 ml||0||0|
|Milk, 1 cup/250 ml||0||0|
|*Daily value is the amount recommended for daily consumption by the US Food and Drug Administration|
What about iron supplements?
If possible, a dietary deficiency should be treated by improving your diet. However, if your iron deficiency is due to some other cause then you may need to take iron supplements. There are several different forms of iron supplements that are available to treat iron deficiency:
- Ferrous sulfate
- Ferrous fumarate
- Ferrous gluconate
These all have the potential to cause side-effects and are dangerous in overdose, so should always be kept out of the reach of children.
Are there side-effects to treatment?
Side-effects of iron supplements are common: nausea, tummy pain, diarrhoea and constipation. Side-effects may be reduced if lower doses are taken or if the medicine is taken with meals. There are also concerns that excess iron in the gut, over and above what the body needs, may be harmful in the long term, although this is not certain.
There are things you can do to help your body to absorb iron, which may reduce the side-effects of iron tablets, but also help you to absorb as much of the iron in your diet as possible. You can read more about this in the following section on prevention.
New forms of iron supplements have been created as nanoparticles. It is hoped that, in future, nanoparticle iron will be better absorbed and have fewer side-effects than currently available forms.
What is the outlook?
Iron deficiency should resolve with treatment. If iron supplements are required, it is usually recommended that they should be taken for three months.
Iron deficiency will come back if the cause has not been dealt with.
How can I prevent iron deficiency?
Iron deficiency may be difficult to prevent if it is due to disease - for example, bleeding from the bowels. However, it should be possible to prevent iron deficiency that is due solely to not having enough iron in your diet. See the section above on iron-containing foods.
With increasing evidence that we need to limit our intake of meat, particularly red meat, how much iron do we need in our diet? The UK recommended daily intake for an adult man is 8.7 mg. For a woman who has not reached her menopause, this is increased to 14.8 mg. Higher amounts are needed in pregnancy and in children and young people.
Can I do anything to help my body to absorb the iron in my diet?
Vitamin C (also called ascorbic acid) helps the body to absorb non-haem iron from the gut. Vitamin C is found in high amounts in lemons, limes, tomatoes and red peppers - it is partially destroyed by cooking, so these foods will help more if you eat (or drink) them raw with your meal.
Lactic acid fermented vegetables may also aid the absorption of non-haem iron. Sauerkraut and kimchi are examples of lacto-fermented vegetables.
Calcium, which is present in milk, yoghurt and cheese, interferes with the absorption of both haem iron and non-haem iron. So drinking cow's milk is best avoided during mealtimes. However, research has suggested that lactobacillus, such as is used in the production of live yoghurt, may aid in the absorption of non-haem iron.
Tea and coffee are best avoided at mealtimes too. This is because they contain chemicals called phenols which interfere with the absorption of non-haem iron.
Further reading and references
Scientific Advisory Committee on Nutrition Iron and Health Report; Public Health England, February 2011
Micronutrient Deficiencies, Iron Deficiency Anaemia; World Health Organization
Iron Dietary Supplement Fact Sheet; Office of Dietary Supplements, National Institutes of Health
Wheal MS, DeCourcy-Ireland E, Bogard JR, et al; Measurement of haem and total iron in fish, shrimp and prawn using ICP-MS: Implications for dietary iron intake calculations. Food Chem. 2016 Jun 15201:222-9. doi: 10.1016/j.foodchem.2016.01.080. Epub 2016 Jan 21.
Jackson J, Williams R, McEvoy M, et al; Is Higher Consumption of Animal Flesh Foods Associated with Better Iron Status among Adults in Developed Countries? A Systematic Review. Nutrients. 2016 Feb 168(2):89. doi: 10.3390/nu8020089.
Pereira DI, Bruggraber SF, Faria N, et al; Nanoparticulate iron(III) oxo-hydroxide delivers safe iron that is well absorbed and utilised in humans. Nanomedicine. 2014 Nov10(8):1877-86. doi: 10.1016/j.nano.2014.06.012. Epub 2014 Jun 28.
Hoppe M, Onning G, Berggren A, et al; Probiotic strain Lactobacillus plantarum 299v increases iron absorption from an iron-supplemented fruit drink: a double-isotope cross-over single-blind study in women of reproductive age. Br J Nutr. 2015 Oct 28114(8):1195-202. doi: 10.1017/S000711451500241X.
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