If your need for dietary iron isn’t met, your body’s iron stores will become depleted. This can lead to iron deficiency and, if severely depleted, anaemia.
Iron is an important dietary mineral that is found in every cell of the body.
- Lack of iron is the most common nutrient deficiency worldwide.
- Women and preschool children are most at risk.
- Common causes include poor diet or low intake, vegetarian diet and heavy periods (for women).
- Treatment is with iron supplements and increasing sources of iron in what we eat.
- See your doctor if there is no clear reason for iron deficiency, as sometimes this is a sign of other problems.
What is iron?
Iron is one of 20 minerals found in food. It is stored in your liver, spleen and bone marrow. Your body needs iron for your red blood cells to carry oxygen around your body and for proteins in your muscles. Iron is also needed for many other roles including your immune system to help fight infections, and is vital for normal child growth and intellectual development. If you do not have enough, you may lack energy and get sick often. Iron is needed for optimum brain function in adults and children.
Causes of low iron levels include blood loss, poor diet, or a problem with your gut not absorbing enough iron from foods you eat. You may develop iron deficiency if you do not eat iron-rich foods for a long period of time. Iron deficiency can be due to lengthy illness or losing blood from heavy periods or stomach ulcers – bleeding from some cancers is a rare but important cause.
In New Zealand and Australia, the groups most at risk of low iron are children, menstruating women, pregnant or breastfeeding women and older adults. People need more iron at certain times, such as in adolescence, pregnancy or when exercising a lot.
Drugs, eg, aspirin and some anti-inflammatories can also cause bleeding in the gut which can lead to a deficiency.
Your doctor can check you have no serious cause for iron deficiency.
Girls & women
Women need more iron because of blood loss during their periods. They also need more than double the usual intake of iron during pregnancy. Women (or men) who follow restrictive or fad diets can become iron deficient.
Infants & young children
Iron deficiency in preschool children in New Zealand is a cause for concern, with up to a quarter of those under 3 years of age having low iron. Even though severe iron deficiency, which can cause anaemia, is rare, low iron levels can have a permanent impact on brain development, making such children less able to learn.
Iron-deficient youngsters may also not gain enough weight, have problems with feeding and digestion, get tired easily and be more prone to infections and illness. Children between 6 and 24 months are at greatest risk, especially those from lower-income families.
Teenagers & athletes
Teenagers need extra nutrients to fuel growth spurts, but they are also more likely to have a poor diet. Iron is lost through excessive sweating and some athletes (particularly those for whom weight is an issue) may have unbalanced diets.
Vegetarians & vegans
Iron in plant foods is not as easily absorbed as iron found in meat, so vegetarians and vegans may get too little iron. You should tell your doctor if you have a non-meat diet so he or she can test you for iron deficiency and, if necessary, refer you to a dietitian for advice. If you eat a vegetarian diet, you may need to take iron tablets. Talk to a health professional about this.
There may be no symptoms, or you may lack energy or your skin and the inside of your mouth may be pale. If you go on to develop iron-deficiency anaemia, you’ll feel even more tired because not enough oxygen is getting to your cells.
You may be unable to do very physical tasks, be unable to concentrate and find learning difficult, have headaches, be irritable or be more prone to infections. Older people may get heart pain or angina, as the heart has to work harder to supply enough oxygen to the body.
You may have some of the symptoms already mentioned, or you may only find out if you have a routine blood test that reveals low iron levels or anaemia. More tests may be needed to check for any medical condition causing your iron deficiency.
If there are causes for your iron deficiency other than inadequate intake of iron then these causes need to be treated. However, iron deficiency can most often be corrected by iron supplements and/or changes to your diet. Your blood count may have to be checked regularly to make sure the problem has not returned.
Iron tablets may be prescribed, but if you need a lot of additional iron your doctor may give you an injection. Iron tablets turn your bowel motions black and can cause indigestion, constipation, diarrhoea or nausea. If so, your doctor may change them. Vitamin C also helps you absorb the iron in iron tablets.
A small number of people are at risk of storing too much iron, so iron supplementation should only be done under the supervision of a doctor and reviewed periodically.
Infants & young children
Breast milk contains enough iron for babies until 6 months of age. Meat, where possible, or iron-fortified cereals should be introduced by 6to 8 months. Bottle-fed or weaned babies should have iron-fortified formula until 12 months of age.
- Cow’s milk should not be given in the first year of life. It is not a good source of iron and can cause stomach upsets with some bleeding in the gut and further iron loss.
- Tea should not be given to preschoolers as it prevents iron absorption.
Make sure your child’s diet is well balanced and contains a wide variety of the iron-rich foods mentioned above. Refer to Plunket guidelines on when to introduce different foods. A liquid iron supplement may be necessary if your child has iron deficiency.
Your body absorbs only a small amount of iron at any one time, so it is important to eat a lot of iron-rich foods every day. To get the most out of those foods remember:
- eating foods rich in vitamin C (citrus fruits, leafy green vegetables) will help iron absorption
- drinking milk around meal times or when taking iron tablets can interfere with iron absorption
- drinking tea with meals also reduces iron uptake.
Iron-rich foods for your diet include:
- Meat and fish: beef, lamb (especially kidneys and liver), veal, pork, poultry, mussels, oysters, sardines and tuna.
- Fruits: dried fruits such as prunes, figs, raisins, currants, peaches and prune and blackberry juice.
- Vegetables: greens (spinach, silverbeet, lettuce), beans and peas, pumpkin and sweet potatoes.
- Grains: oatmeal, iron-fortified breakfast cereals and wholegrain breads.
The iron in meat, fish and chicken is called haem iron and is more abundant and more easily absorbed than the iron in vegetables, which is called non-haem iron. It is best to get iron from a variety of sources – protein in meat also helps your gut absorb non-haem iron.
Iron contained in 100g of different foods
|lean beef steak||4.3mg|
|Non-haem iron (harder to absorb)|
- Crampton P, Farrell A, Tuohy P. 1994. Iron deficiency anaemia in infants. NZ Med J 107:60-61.
- Grant CC, Wall CR, Brunt D, Crengle S, Scragg R. 2007. Population prevalence and risk factors for iron deficiency in Auckland, New Zealand. J Paediatr Child Health; 43: 532–8.