'Nearly 60 percent of children who die of common diseases like diarrhea and malaria could have ultimately survived had they not been malnourished in the first place,' said Jean-Louis Sarbib, World Bank's senior vice president for human development.

In a report, the bank cites a medical consensus that damage to physical growth and brain development during this period is extensive.

"Therefore interventions must focus on this window of opportunity," the report said. "Any investments after this critical period are much less likely to improve nutrition."

Food Production May Not Be Most Important

Meera Shekar, the report's lead author and a senior bank nutrition specialist, said, "If we miss this window, we have missed the opportunity to address an entire generation of children."

In many countries where malnutrition is widespread, the report said, food production is not the limiting factor unless there is famine.

Some of the most important factors are:

Nutrition Investment a 'Best Buy'

According to the report, "Repositioning Nutrition as Central to Development," malnutrition long has been known to undermine economic growth and perpetuate poverty. Yet over previous decades, international aid organizations and most governments in developing countries have failed to tackle nutrition, even though well-tested approaches for doing so exist.

"The unequivocal choice now is between continuing to fail, as the global community did with HIV/AIDS for more than a decade, or to finally put nutrition at the center of development so that a wide range of economic and social improvements that depend on nutrition can be realized," the report said.

A group of the world's leading development economists, including three Nobel laureates, concluded in a 2004 study know as the Copenhagen Consensus that nutrition investments were one of the best buys that developing countries could make in reducing poverty and improving economic growth.

"For example, nearly 60 percent of children who die of common diseases like diarrhea and malaria could have ultimately survived had they not been malnourished in the first place," said Jean-Louis Sarbib, the bank's senior vice president for human development.

He said improving nutrition can add 2 percent to 3 percent to the gross domestic product of developing countries and drive their economic growth.

Highest Malnutrition Rates in South Asia

Contrary to common perceptions, malnutrition prevalence rates in the heavily populated South Asian countries -- India, Bangladesh, Afghanistan and Pakistan -- are much higher, 38 percent to 51 percent, than in sub-Sahara Africa, where it is 26 percent. Malnutrition is rising there, however.

In East Asia, Latin America and Eastern Europe, many countries have serious problems of malnutrition. Among them are Cambodia, Indonesia, Laos, the Philippines and Vietnam in Asia and Guatemala, Haiti and Honduras in Latin America.

The report said donor countries must reverse the current situation where far too little money is devoted to fighting nutrition. To help achieve this, development organizations will need to co-finance a grant fund to start action and complement a recent World Bank grant of $3.6 million (€3 million) for nutrition programs.