Pediatric Nutrition in Practice

Micronutrient Deficiencies in Children 149

3

B 12 ) can also contribute to anemia. Thus, supple-
menting only with iron may not be effective in
correcting nutritional anemia. Therefore, MMN
supplementation in poverty settings may better
address the issue of anemia [5, 11].

Vitamin A Deficiency

An estimated 0.9% or 5.2 million of the world’s
preschool-age population suffers from night
blindness, and approximately 90 million have
subclinical VAD. The prevalence is higher in
Africa than elsewhere [1]. Clinical assessment of
eye symptoms (night blindness and xerophthal-
mia) and biochemical assessment of serum reti-
nol are the two commonest methods for the esti-
mation of VAD prevalence in communities [1,
2]. VAD is most common during childhood. The
reasons are multiple; they include widespread
maternal undernutrition, poor dietary quality
and losses during diarrhea [12, 13]. A Cochrane
review of 43 randomized trials showed that vita-
min A supplementation reduced all-cause mor-
tality by 24% and diarrhea-related mortality by
28% in children aged 6–59 months [14]. The cor-
responding Cochrane review on vitamin A sup-
plementation to neonates showed a 14% reduc-
tion in the risk of infant death at 6 months in
neonates supplemented with vitamin A com-
pared to controls [15]. The prevalence of VAD
has declined over time because of large-scale
vitamin A supplementation programs in many
developing countries.

Zinc Deficiency

More than half of the populations of developing
countries are at an increased risk of low dietary
zinc intake [16]. Zinc is a key micronutrient and
essential for normal functioning of the body. The
biological functions affected by a zinc deficit in-
clude protein synthesis, cell replication and nu-

cleic acid metabolism [1, 16, 17]. Preventive zinc

supplementation is associated with a reduction in

morbidity from childhood diarrhea and decreas-

es the severity of lower respiratory infection; it

may also contribute to an improved linear growth

and weight gain in infants and young children in

populations where diarrhea is prevalent and the

risk of zinc deficiency is higher [18, 19].

A systematic review showed that zinc supple-

mentation resulted in a 9% reduction (RR 0.91,

95% CI 0.82–1.01) in all-cause child mortality

[20]. Another analysis showed a significant 18%

reduction (RR 0.82, 95% CI 0.70–0.96) in all-

cause mortality in children aged 1–4 years [19].

However, there is no convincing evidence that

zinc supplementation to infants and children re-

sults in improved motor or mental development

[8, 21].

Iodine Deficiency

Global estimates suggest that approximately 1.9

billion individuals are iodine deficient [1, 22]. A

large part only suffers from a mild deficiency, but

even a subclinical maternal iodine deficiency is

associated with impaired motor and mental de-

velopment in the fetus and increases the risk of

miscarriage and fetal growth faltering [2, 23]. It

also causes cretinism if the deficiency is severe.

The full extent of mild or moderate iodine defi-

ciency on infant brain development is not fully

established. Iodine fortification is a cost-effective

way of reducing the prevalence of iodine defi-

ciency worldwide.

Provision of MMN rather than Two or Fewer

Micronutrients to Micronutrient-Deficient

Children

Deficiencies in MMN usually co-occur in devel-

oping country settings and are generally associ-

ated with poor-quality diets. Most national sup-

Koletzko B, et al. (eds): Pediatric Nutrition in Practice. World Rev Nutr Diet. Basel, Karger, 2015, vol 113, pp 147–151
DOI: 10.1159/000375276