DUBLIN, Ireland – More than a quarter of children under age 5 worldwide are permanently "stunted" from malnutrition, according to the United Nations Children's Fund, leaving them physically and intellectually weak and representing a scandalous waste of human potential.

Anthony Lake, executive director of UNICEF since 2010, said organized provision of vitamins and clean water and a focus from birth on breast-feeding could have helped these 165 million children achieve ­normal brain and body development. But their lack of proper nutrition means instead they will suffer increased ­vulnerability to illness and early death.

"Stunting is the least understood, least recognized and least acted upon crisis. It is a hidden crisis for these ­children," said Lake, a veteran U.S. diplomat.

Lake said the failure to give children enough vitamin A, iron and folic acid when developing in the womb, and a ­balanced diet with clean drinking water in the first two years of life, doomed most of them in their impoverished societies.

"Stunted doesn't mean simply short," Lake said in an interview. "The child's brain never properly develops. Irrevocably. That's it. You can't fix it later. You can fix being underweight. You can't fix being stunted after age 2."

Lake was in Dublin to present the findings in a report at a global conference focused on combating hunger and ­malnutrition. He showed slides of CT scans of stunted ­children's brains, with weaker cell and nerve development.

"What this means is, for the remainder of that child's life, irrevocably the child will learn less in school, will earn less later, is more vulnerable to ­disease," he said.

The U.N. report found that 24 countries with the highest levels of stunted children were concentrated in sub-Saharan Africa and South Asia. More than half of those under age 5 in Timor-Leste, Burundi, Niger and Madagascar suffered from stunting. The country with the largest number of stunted children is India with 61.7 million, or 48 percent of all Indians under age 5.

Lake said the problem of stunted child development was growing in Syria because of its civil war and widespread disruption to medical care, schools and family life.