Living at higher altitude is associated with greater rates of stunting, even for children living in what are deemed to be ideal-home environments, according to a new study.
Researchers from the International Food Policy Research Institute (IFPRI) and Ethiopia’s Addis Ababa University (AAU) analysed height-for-age data for more than 950,000 children from 59 countries compiled through the Advancing Research on Nutrition and Agriculture (AReNA) project.
Children were classified as living in an ideal-home environment if they were born to highly educated mothers and 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. But that is not always the case.
“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 Organisation (WHO), but only until about 500 metres above sea level,” says the IFPRI’s Kalle Hirvonen.
“After 500 [metres], average child height-for-age significantly deviated from the growth curve of the median child in the reference population.”
The research also shows that these estimated growth deficits are unlikely to be due to common risk factors such as poor diet and disease.
More than 800 million people actually live at or above 1500 metres, two-thirds of whom are in Sub-Saharan Africa or Asia – the regions with most of the world’s stunted children
“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,” Hirvonen says.
The study suggests the effects of altitude are most pronounced during the perinatal period – the time leading up to and immediately after birth.
There is some evidence to suggest living at 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. “[I]t may take more than a century before such adaptions are developed”, says AAU’s Kaleab Baye.
The study is published in the Journal JAMA Pediatrics.
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