Poor nutrition in school years has helped create a height gap of as much as 20 centimetres between children in different parts of the world, according to a new study.
Researchers led by Imperial College London (ICL) analysed data on 65 million children, aged five to 19, in 193 countries, and found enormous differences in height and weight – both indicators of health and quality of diet.
The 20-centimetre difference for 19-year-olds represented an eight-year growth gap for girls, and a six-year gap for boys. The average 19-year-old girl in Bangladesh and Guatemala (which have the shortest girls) is the same height as an average 11-year-old girl in the Netherlands, which has the tallest boys and girls.
Analysis also revealed that, in many nations, children at age five have a height and weight in the healthy range defined by the World Health Organisation (WHO). However, after this age some experience too small an increase in height, and gain too much weight, compared to the potential for healthy growth.
“This shows that there is an imbalance between investment in improving nutrition in pre-schoolers, and in school-aged children and adolescents,” says ICL’s Majid Ezzati, senior author of a paper in the medical journal The Lancet.
“This issue is especially important during the COVID-19 pandemic when schools are closed throughout the world, and many poor families are unable to provide adequate nutrition for their children.”
The nations with the tallest 19-year-olds in 2019 were in northwest and central Europe, and also included Montenegro, Denmark and Iceland. The shortest were mostly in south and southeast Asia, Latin America and East Africa, including Timor-Leste and Papua New Guinea.
The largest improvements in average height of children over the 35-year study period were seen in emerging economies such as China, South Korea and some parts of southeast Asia.
For example, 19-year old boys in China in 2019 were eight centimetres taller than in 1985, with their global rank changing from 150th tallest in 1985 to 65th in 2019. In contrast the height of children, especially boys, in many sub-Saharan African nations has stagnated or reduced over these decades.
The study also assessed children’s Body Mass Index (BMI), a measure of height to weight ratio and thus an indicator of healthy weight. The analysis found that 19-year-olds with the largest BMI were found in the Pacific islands, the Middle East, US and New Zealand.
The BMI of 19-year-olds was lowest in south Asian countries such as India and Bangladesh. The difference between the lightest and the heaviest BMIs in the study was around nine units of BMI (equivalent to around 25 kilograms of weight).