Iron deficiency remains a common condition in children, with research suggesting many negative effects on the developing child, writes Siobhan O’Sullivan
Iron deficiency is the most common and widespread nutritional disorder in the world.1 The World Health Organisation (WHO) estimate that iron deficiency accounts for 40-50% of anaemia in children and up to 80% in preschool children (2-5 years old) worldwide.1 High-risk groups for iron deficiency have been identified as preterm infants, children aged 1½-3½, and girls aged 11-18 years.2
Irish research shows that iron intake is a concern among all age groups. These concerns are outlined below:
Consequences of iron deficiency in children
Iron is an essential nutrient. It is a component of haemoglobin and myoglobin which transport and store oxygen around the body. It is also a component of many enzymes which are involved in the metabolism of energy and protein.2 Requirements for iron are highest during periods of rapid growth due to its role in cell development. Therefore, children are at greater risk of iron deficiency than full grown adults.
Iron deficiency results in defective erythropoiesis leading to a normocytic or microcytic hypochromic anaemia. Studies suggest that iron deficiency anaemia is a cause of poor motor development in children in the first three years of life. This may be explained by the role of iron in brain development or may be due to behavioural issues.
The amount of iron in the brain increases throughout childhood and early adult life. Suggested roles of iron in the brain include a role in myelin sheath production and acting as a catalyst in the synthesis of neurotransmitters such as dopamine and serotonin. It is thought that iron deficiency may impair certain pathways and this may be a cause of cognitive impairment. Another potential role is the functional isolation which can be associated with iron deficiency due to symptoms such as poorer concentration and less energy to move around and play, thereby reducing cognitive stimulation.
In older children, iron deficiency is thought to effect cognitive development, with studies suggesting that treatment of iron deficiency in this age group (older than three years) can improve school achievement.2 However, the long-term implications of these findings are unknown, as are thresholds at which these complications occur. The aim would be to maintain iron stores within the range outlined by the WHO (see Table 1).
|Haemoglobin and serum ferritin levels*|
|* The World Health Organisation threshold for adequate haemoglobin and serum ferritin concentration|
Studies suggest that iron deficiency may also have an effect on physical growth. Improved growth is noted when iron supplementation is commenced in children with iron deficiency anaemia.1
Identifying iron deficiency in children
Common symptoms of iron deficiency children include paleness, tiredness, irritability and poor appetite. If iron deficiency is suspected it is important that it be diagnosed with a blood test prior to iron supplementation to prevent iron overload, which is associated with its own complications.
The WHO threshold for adequate haemoglobin and serum ferritin concentration (see Table 1) can be used as a reference guide.8 Serum ferritin can be a useful marker of iron stores which may be deplete before the development of iron deficiency anaemia.
Recommended iron intake for children
The Food Safety Authority of Ireland’s recommended dietary allowances (RDA) 1999 for iron9 are described in Table 2. The RDA’s describe the amount of iron that should meet the nutritional needs of practically all healthy individuals.
|Recommended daily allowance of iron*|
|Age group (years)||Male (mg/d)||Female (mg/d)|
|* Food Safety Authority of Ireland’s (FSAI) recommended dietary allowances (RDA) 1999|
Iron requirements for toddlers and children are higher than those of adults (per kg of body weight) due to the high requirements for growth. These high intakes can be difficult to achieve, so particular attention needs to be paid to iron during weaning and childhood/adolescent years.
Dietary management of iron deficiency
Treatment of iron deficiency usually involves taking iron supplements to replace the missing iron and treating any underlying causes (eg. low dietary intake, blood loss). Dietary iron exists in two forms: haem (found almost exclusively in meat) and non-haem sources. Haem iron is two to six times more available for absorption from the diet than non-haem iron.
Sources of haem iron include:
As children’s iron stores are usually depleted by the age of six months, it is essential to include sources of haem iron in the weaning diet from six months. For toddlers and older children haem sources of iron should be included in the diet daily, with red meats being given a minimum of three times per week.
Non-haem iron can also contribute to dietary iron intake. Non-haem iron absorption capacity will be improved if taken with a source of vitamin C. This is likely due to prevention of the formation of insoluble iron compounds and the reduction of ferric to ferrous iron, which seems to be a requirement for the uptake of iron into the mucosal cells.
Good sources of non-haem iron include:
Good sources of vitamin C include:
For example, the amount of iron absorbed from a bowl of fortified breakfast can be increased if taken with a glass of orange juice.
Tannins found in tea and coffee may reduce iron absorption as they bind to the iron forming insoluble complexes. Tea is not a suitable drink for young children and is not recommended for those under 12 years old. However, studies suggest that 12% of toddlers are given tea as a main drink. In teenagers, tea should not be given with/directly after a meal.
Excessive cow’s milk intake is also a known contributor to iron deficiency anaemia. This is because cow’s milk is a poor source of iron and when taken excessively can displace other good sources of iron in the diet (eg. a toddler having a bottle in place of their dinner). Toddlers should limit their intake of cow’s milk to no more than one pint per day (full fat milk only should be used in those under two years old due to their high energy needs for growth).
Another concern is the early introduction of cow’s milk into the diet. The FSAI recommend that cow’s milk is not suitable as
a main drink in children less than one year old,3 partly due to its insufficient iron content. Breast milk or infant formula (which is fortified with iron as per EU guidelines) should be used in conjunction with the weaning diet until the child is one year old.
Iron deficiency remains a common condition in children, with research suggesting many negative effects on the developing child. Many children continue to fail to meet their daily iron requirements, however, simple dietary adjustments, along with supplementation where indicated, can help alleviate this problem.
Siobhan O’Sullivan is a dietician at Our Lady’s Children’s Hospital in Crumlin
|Continuing Education - Child Health - Iron deficiency: The developing child at risk|