Werner Schultink, Unicef's Associate Director of Nutrition: "This has a big impact on the child mortality figures"
Poor child nutrition still causes major problems in the developing world - despite some progress, experts say.
A third of deaths in children under five in those countries are linked to poor diet, a report by Unicef suggests.
It also reveals 195m children - one in three - have stunted growth, even though rates have fallen since 1990.
Unicef said the number of underweight children also remained high, with many countries struggling to hit official targets to halve the figures.
An estimated 129m children are underweight.
Rates of stunted growth are higher because while some children may be a normal weight - in fact some can even be overweight - the food they are getting is of such poor quality they they have growth problems.
Experts warn that such a condition is often irreversible and effectively condemns children to a lifetime of poor health.
Unicef chief Ann Veneman said: "Undernutrition steals a child's strength and makes illnesses that the body might otherwise fight off far more dangerous.
"Unless attention is paid to addressing the causes of child and maternal undernutrition today, the costs will be considerably higher tomorrow."
HOW TO TACKLE THE PROBLEM
Poor nutrition has traditionally been a problem for Peru
In 1999, the government, in partnership with Unicef and the US International Development Agency, set up the Good Start in Life programme
The project used health staff to provide ante-natal support to mothers, promote breastfeeding and offer food supplements in five mainly rural regions
By 2004, more than 75,000 children under three were benefiting and rates of stunted growth fell from 54% to 37%
A national programme is now being rolled out
The organisation has pinpointed the first 1,000 days of life as the key period in which to tackle the problem.
It said promoting breastfeeding as the exclusive source of nutrition for the first six months and continued breastfeeding until at least two was essential.
But Unicef said providing access to food supplements was also an important part of the solution.
Many aid programmes are focusing on iodised salt to aid brain development and vitamin A supplements, which help bone growth and the body's ability to fight infection.
Such steps, the report suggested, could reduce deaths by a fifth.
Unicef said that together with its partners, which include governments and international aid agencies, it was making progress to improve nutrition for children in the 150 countries it was working in.
Indeed, since 1990 the proportion of children underweight in the developing world has fallen by a sixth, according to figures compiled from Unicef's own monitoring schemes and data provided by other bodies such as the World Health Organization and World Bank.
Millions of children in India are malnourished
And stunted growth rates have dropped by a quarter over the same period.
Nonetheless, just 63 out of 117 countries look like they will meet the Millennium Development Goal of halving the rates of underweight children between 1990 and 2015.
Progress has been particularly poor in Africa. Asia is performing a little better, although India is making little progress, while South America is making some significant strides.
Kitty Arie, a senior policy adviser at the Save the Children charity, also pointed out poor nutrition had long-term consequences, including lower school performance.
"This is an urgent issue that can and must be tackled."
And UK international development minister Mike Foster agreed more could be done.
"We have to work more effectively with our development partners and national governments to make nutrition a priority."
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.