Five-year-old Nikita and her mother Nagamani writing with chalk on the floor. Photos: Save the Children/PA

Chronically malnourished children struggle to read and write simple sentences regardless of their level of schooling, according to research by Save the Children.

A report by the charity Food for Thought shows that eight-year-olds who are stunted by malnutrition are 19 per cent more likely to make a mistake reading simple sentences like “the sun is hot”.

Stunted children are 12.5 per cent more likely to make a mistake writing a simple sentence and do seven per cent worse on basic maths questions.

Save the Children chief executive Justin Forsyth said: “These findings confirm our very worst fears – that poor nutrition is cap-able of seriously damaging a child’s life chances before he or she even sets foot in a classroom.

“We have made huge progress in tackling child deaths, but having a quarter of the world’s children at risk of under-performing at school will have grave consequences for the fight to end global poverty.

Having a quarter of the world’s children at risk of under-performing at school will have grave consequences for the fight to end global poverty

“World leaders must take the opportunity to change this in London on June 8 and commit to tackle the scourge of malnutrition for good. We want to see funding for countries suffering the highest burden so that millions of child-ren’s lives can be transformed.”

The findings, based on research with thousands of children in Ethiopia, India, Peru and Vietnam, come 10 days before a global nutrition summit in London and before this year’s G8.

The global economic impact of malnutrition could be up to £80bn, according to Save the Children.

Shambel, a 12-year-old from Ethiopia, said: “Those children who come to school after having their breakfast do well. This is difficult for me as I don’t get enough to eat.”

Gatluak, a 10-year-old from South Sudan, said: “When I was going to school I used to struggle with lessons because I had often gone without any food.”

One in four children worldwide are believed to be stunted, and Save the Children’s research points to a literacy and numeracy crisis in the developing world.

Although one of the most cost-effective forms of development assistance, nutrition programmes are just 0.3 per cent of global development spending.