Agriculture Reference
In-Depth Information
s
t u D i e s
of f
t h e
b
e n e f i t s
of f
P
r e v e n t i v e
s
u P P L e m e n t a t i o n
A number of trials have been conducted of the effects of giving iron-fortified formula
to healthy infants compared with usual formula or cow's milk. These have shown no
benefit (Morley et al. 1999), short-term benefits to motor development (Moffatt et al.
1994), or significant benefits to overall developmental scores (Williams et al. 1999).
In a trial of iron supplementation of healthy breast-fed infants, those who received
iron had better visual acuity and motor development at 1 year, but there were no
benefits to mental development (Friel et al. 2003). In Chile, well-nourished infants
who received iron-fortified formula for 6 months from age 6 months had benefits to
recognition memory and social-emotional outcomes compared with infants on non-
fortified formula but had no benefits on the mental and motor scales of the Bayley
Scales of Infant Development (Lozoff et al. 2003).
Four trials of preventive iron supplementation have been conducted in developing
countries among populations at high risk of both stunting and anemia. All studies
showed benefits to children's motor development, although in one this was only when
iron and zinc were both given (Stoltzfus et al. 2001, Black et al.. 2002, 2004a, Lind et
al. 2004). None of the studies showed benefits to mental development, although one
benefited language, and two showed benefits to social emotional outcomes.
IDA is associated with concurrent cognitive delays and behavioral changes, and
follow-up studies indicated that there are long-lasting effects. Some studies of treat-
ment lasting at least 2 months have shown benefits to development, with the findings
from older children being more consistent. Preventive supplementation has also led to
developmental benefits, primarily to motor and socioemotional outcomes. Although
there are some conflicting findings, the body of research on IDA indicates the need
for strategies to reduce the prevalence of IDA in young children.
zInc
Zinc deficiency is thought to be highly prevalent in undernourished children. It has
been linked to reduced activity and play (Sazawal et al. 1996, Bentley et al. 1997)
and may exacerbate undernourished children's poor development. Zinc deficiency
is associated with growth retardation (Brown et al. 1998) and increased rates of
diarrhea and pneumonia in children (Zinc Investigators Collaborative Group 1999),
which could indirectly link zinc deficiency with poor development. However, evi-
dence of associations between zinc and development is inconsistent in young chil-
dren (Hamadani et al. 2002, Black 2003a, Lozoff and Black 2004) and among
school-aged children (Lozoff and Black 2004).
More than a dozen studies have reported the effects of zinc supplementation on
young children's activity, development, or behavior. Unfortunately, the findings vary
considerably, with some studies showing benefits, others no change, and others nega-
tive effects. It is difficult to draw conclusions from such a disparate set of findings.
The only two studies reporting activity levels indicated a benefit with zinc supple-
mentation (Friel et al. 1993, Sazawal et al. 1996). Some aspects of behavior improved
in two of the studies (Ashworth et al. 1998, Black et al. 2004a), but there was no
