Agriculture Reference
In-Depth Information
Zinc ........................................................................................................................ 173
Vitamin A ............................................................................................................... 174
Vitamin B
12
............................................................................................................. 174
Conclusions............................................................................................................ 175
References.............................................................................................................. 175
AbstRAct
This chapter presents the evidence linking inadequate nutrition in children with
poor developmental outcomes. Children are most likely to experience undernutri-
tion in the early years, coinciding with the period of greatest brain development.
Chronic undernutrition can result in linear growth retardation or “stunting,” which
affects about one third of children under 5 years in developing countries. There are
other markers of poor nutrition, including deficiencies of micronutrients and insuf-
ficient breastfeeding, that may also affect children's development. There is very
strong evidence that iodine deficiency causes cognitive deficits, leading to cretinism
as well as less-devastating deficits in development. There is also strong evidence
that chronic undernutrition leading to linear growth retardation and iron deficiency
anemia have long-lasting effects on children's cognitive development and behav-
ior. There is an urgent need for strategies to reduce the numbers of children who
become undernourished and the negative impact on children's development as well
as to strengthen efforts to prevent iodine deficiency in mothers and children. It also
appears important that efforts are made to reduce iron deficiency anemia among
women and children. Most studies suggest that breastfeeding is associated with a
small benefit in IQ, but problems with the study designs and interpretation have not
been fully addressed. Several other nutrients, such as zinc, vitamin A, and vitamin
B
12
, may affect children's development, but the evidence is inconsistent, and further
research is needed.
IntRoductIon
The growth potential of young children is similar across different populations (WHO
Multicentre Growth Reference Study Group 2006). Faltering in linear growth results
from chronic undernutrition and high levels of infections (Waterlow 1992). Reduction
in growth rates occurs early, sometimes beginning in utero, and is most common in
the first 2 years of life. The first years are also the most critical period for child
development; thus, children are most likely to experience undernutrition during the
period when the brain is developing rapidly and can be affected by the quality of the
environment, including nutrition.
Linear growth retardation or stunting is defined as height-for-age less than or
equal to 2 standard deviations (SD) of reference values. One third of children under
5 in developing countries are stunted (UNICEF 2004), with as many as 50% of
children stunted in some countries. Thus, the implications for the development of
children in many countries are enormous. Children's nutritional intake may be inad-
equate in micronutrients as well as energy and protein. In this chapter, we describe
