Living at higher altitudes associated with higher levels of child
stunting
New global analysis indicates need to tailor nutrition interventions to
high altitude contexts

Date:
August 24, 2020
Source:
International Food Policy Research Institute
Summary:
Children living at high altitudes found to be more stunted, on
average, than peers at lower altitudes. The deficit increases
above 500 meters above sea level, and persists as children age,
indicating the need to tailor nutrition interventions targeted at
children living in high altitudes.



FULL STORY ========================================================================== Residing at higher altitude is associated with greater rates of stunting,
even for children living in "ideal-home environments" according to a new
study from researchers at the International Food Policy Research Institute (IFPRI) and Addis Ababa University. The study provides new insight in
the relationship between altitude and undernutrition and the additional
efforts needed to ensure policy interventions are appropriately tailored
to high altitude contexts.


========================================================================== "More than 800 million people live at 1,500 meters above sea level or
higher, with two-thirds of them in Sub-Saharan Africa, and Asia. These
two regions host most of the world's stunted children so it is important
to understand the role that altitude plays in growth" said IFPRI Senior Research Fellow and co-author of the study, Kalle Hirvonen.

"If children living at altitude are, on average, more stunted than
their peers at sea level, then a more significant effort to address high altitude stunting is needed." The study, "Evaluation of Linear Growth
at Higher Altitudes," co-authored by Hirvonen and Addis Ababa University Associate Professor Kaleab Baye, was published in the Journal of the
American Medical Association (JAMA), Pediatrics. The study analyzed height-for-age data of more than 950,000 children from 59 countries. The
data were compiled through the Advancing Research on Nutrition and
Agriculture (AReNA) project funded by the Bill & Melinda Gates Foundation.

Children were classified as having lived in an ideal-home environment
if they were born to highly educated mothers, had good health-service
coverage and high living conditions. Global tracking of growth rates
relies on the assumption that children living in such environments have
the same growth potential, irrespective of genetic makeup or geographic location.

"The data clearly indicated that those residing in ideal-home environments
grew at the same rate as the median child in the growth standard developed
by the World Health Organization (WHO), but only until about 500 meters
above sea level (masl). After 500 masl, average child height-for-age significantly deviated from the growth curve of the median child in the reference population," said Hirvonen. The research further shows that
these estimated growth deficits are unlikely to be due to common risk
factors such as poor diet and disease.

The study suggests that the effects of altitude were most pronounced
during the perinatal period i.e., the time leading up to, and immediately after, the birth. "Pregnancies at high-altitudes are characterized by
chronic hypoxia, or an inadequate supply of oxygen, which is consistently associated with a higher risk of fetal growth restriction. Restricted
growth in the womb is in turn a leading risk factor for linear growth faltering" said Hirvonen.

There is some evidence to suggest that residing at high altitude
over multiple generations may lead to some genetic adaption, but
these findings did not hold for women with only a few generations of high-altitude ancestry. "Women of high-altitude ancestry were able to
partially cope with the hypoxic conditions through increased uterine
artery blood flow during pregnancy, but it may take more than a century
before such adaptions are developed," said Baye.

Hirvonen and Baye conclude that the WHO growth standards for children
should not be adjusted because growth faltering at high altitudes
is unlikely to be the result of physiological adaptations. Instead,
they call for greater attention and health-care guidance for managing pregnancies in high-altitude settings.

"A first step is to unravel the complex relationship linking altitude,
hypoxia and fetal growth to identify effective interventions. Failing to address altitude-mediated growth deficits urgently can fail a significant proportion of the world population from meeting the Sustainable
Development Goals and World Health Assembly nutrition targets" said Baye.


========================================================================== Story Source: Materials provided by International_Food_Policy_Research_Institute. Note: Content may be edited
for style and length.


========================================================================== Journal Reference:
1. Kaleab Baye, Kalle Hirvonen. Evaluation of Linear Growth at Higher
Altitudes. JAMA Pediatrics, 2020; DOI:
10.1001/jamapediatrics.2020.2386 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/08/200824120038.htm

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