Iron in infant and child development
by Dr Geoffrey Cleghorn
Iron is one of the most ubiquitous minerals in the environment.
The amount needed by humans for proper health and well-being is relatively minute.
Despite these, lack of iron in the diet remains the most prevalent nutritional deficiency
in both developing and developed countries, particularly among infants and young
children, adolescents and expectant mothers.
Iron deficiency anaemia, a consequence of iron deficiency, is known to adversely
impair growth and development of infants and young children. The good news is that
it is preventable and with awareness and knowledge, parents and caregivers are able
to take the necessary steps to prevent it.
To share his views and expertise in the area of iron and its role in infant and
child growth and development is Dr Geoffrey Cleghorn, an Associate Professor and
Head of the Department of Paediatrics and Child Health at the University of Queensland,
Australia. He is currently the Clinical Director of the Children's Nutrition Research
Centre and the Department of Paediatric Gastroenterology at the Royal Children's
Hospital in Brisbane.
Dr Cleghorn has published more than 80 manuscripts and book chapters and is a seasoned
lecturer and public speaker on a number of infant related issues including perinatal
and paediatric nutrition. His research interests include the use of energy expenditure
and body composition analysis in a number of disease states including chronic liver
disease, cystic fibrosis, and general nutritional rehabilitation.
The Role of Iron in Infant and Child Growth and Development
Interview with Dr Geoffrey Cleghorn
by Lauren F. Ho
Nutrition Manager/Dietitian
Q1) Is iron deficiency regarded a global medical concern
among children and what is its prevalence in the world and in Asia?
Iron deficiency remains the commonest micronutrient deficiency throughout
the world. There is approximately 4 billion people throughout the world who have
iron deficiency and almost half of them have iron deficiency anaemia. WHO regards
it as the major problem in respect to micronutrient deficiency throughout the world.
Q2) What are the major causes of iron deficiency in children?
Clearly, the major problem of iron deficiency in children is one
of dietary insufficiency. There's either inadequate iron in the diet or inappropriate
use of iron-poor foods, such as pasteurised or unprocessed milk. Many areas in the
world, including Asia and the developing world have cereals as a source of iron.
Cereals are a poor source of iron because of their high phytate levels and other
inhibitors to iron absorption.
Q3) Infants aged 4 months and above are at risk of developing
iron deficiency. Why is that so?
The principle reason for this is that during the second six months
of life continuing into the second year of life, there is a dramatic increase in
the requirement for iron in children's diets. This is primarily because there is
a disproportionate increase in brain growth and iron is preferentially laid down
in the brain during this time. Iron is essential for the development of myelin and
also for the development of the neurotransmitters such as dopamine. Without an increasing
amount of iron in the diet, particularly after four months of age, infants will
inevitably become iron deficient.
Q4) What strategy would you recommend for the prevention
of iron deficiency in infants and young children?
Clearly, the most important strategy for the prevention of iron
deficiency in this age group is to ensure an adequate amount of iron in the diet.
This could be the use of iron-fortification of cereals as weaning foods and also
the early introduction of iron-rich foods such as meat in the diet even in the first
foods.
A balance of iron in the diet would ensure that iron-deficiency would not occur.
Q5) Some studies have shown a correlation between vitamin
C intake and iron status, while others have not. What's your opinion on this?
Vitamin C is an important adjuvant for iron absorption. Studies
have clearly shown a direct relationship between vitamin C intake and iron absorption.
Vitamin C enhances non-heme iron uptake in the small intestine. It is important
that vitamin C is consumed in the form of food, rather than in the form of tablets,
as dietary vitamin C is more effective than pharmacological Vitamin C.
Q6) What are the consequences of iron deficiency in the
growing child?
Iron deficiency anaemia is common in a growing child, particularly
in the second six months of life and through the third six months of life. As a
result, there are significant and perhaps irreversible effects on brain growth and
development. This is most likely due to inadequate and insufficient myelination,
which may result in neurotransmission and neuroconduction problems.
Many studies have shown poor neurodevelopmental and fine motor indices appearing
in these young infants - longstanding deficiencies that are present right through
to at least the age of ten years.
Most of these deficiencies occur in the form of speech and language problems, and
also in areas of gross motor deficiencies.
Q7) Are the symptoms of iron deficiency reversible?
It appears that the symptoms of iron deficiency are irreversible,
in children with iron deficiency anaemia who demonstrate signs of psychomotor problems.
Studies by Tomas Walter and Betsy Lozoff from Chile and Costa Rica respectively,
have shown that deficiencies occurring in young infants seem to become profound
and irreversible, even throughout the age of ten years. One would interpret this
as a permanent deficiency.
Q8) What are the roles of iron in brain development?
Iron is an important micronutrient in neurological physiology. It
is an important nutrient for myelin development and without iron in adequate amounts
in the diet, there would be inadequate myelination in the brain.
The Myelin sheath is an essential part of the neurological architecture that allows
for rapid nerve conduction and all of the functions that we know. The majority of
iron in the brain is deposited in the hippocampus and the extrapyramidal tracts
and the basal ganglia.
Iron-deficiency has been shown to be associated with problems with dopamine synthesis
and therefore neurotransmission. Both of these would result in inadequate nerve
conduction and would inevitably lead to deficiencies in language and speech as well
as in gross motor skills development.
Q9) It is believed that the high iron contents of iron-fortified
infant formulas and cereals promote constipation in infants. What are your views
on this?
I believe that this is in fact a fallacy as there is no real evidence
to support this view. The constipation one sees in infants is most likely as a result
of calcium rather than iron and I do not believe that iron fortification of food
in any way has a role in constipation.
Q10) Iron is also known to play an important role in strengthening
our body's immune function. Does this mean iron deficient children are more prone
to infections and illnesses?
Studies on immune function in children with iron deficiency show
that cellular immune response, including the various types of hypersensitivity and
the bactericidal functions of neutrophils are most consistently depressed during
iron deficiency.
The defects are developed due to a deficiency in iron-containing enzymes, such as
nucleotide reductase, and the differences in iron-storage capacity of various immune
cell types.
However, children with iron deficiency seem to have normal antibody production after
immunization.
Q11: Apart from the symptoms of iron deficiency anaemia
eg. pallour, fatigue, etc., how would parents and caregivers detect iron deficiency
in children?
The symptoms of iron deficiency such as behaviour disturbances,
fatigue and pallor are very difficult to detect. They can in fact be very vague
and nondescript. Moreover, these symptoms can be due to other reasons as well.
It is more important that parents and caregivers think about iron deficiency and
anticipate when this would become a problem as a result of inadequate iron in an
infant's diet, rather than screening all infants as a routine.