Their condition leaves them increasingly exposed to infection, susceptible to illness and account for nearly 53% of deaths that could be otherwise prevented.
"Malnutrition has been the silent crisis for too long," said Susan Grant, country director for Save the Children in Nigeria, noting that it is an underlying cause in at least 2.6 million annual deaths worldwide.
"It is time world leaders invest in tackling child malnutrition and ensure all children have a life free from hunger."
In a new global report A Life Free From Hunger, Save the Children said malnutrition also affected physical and cognitive growth.
Among an estimated 60 million children stunted in Africa, one in every five lives in Nigeria.
The group called on Nigerian government to deploy more nutritionists to deliver quality nutrition services, as well as update its national policy on food and nutrition.
It also wants government to ensure its commitment to better child nutrition are implemented through well funded and transparent institutions.
The government could also "implemented a combination of effective social protection, food fortification, support and education for mothers, as well as support for the growth of the agricultural sector to improve food security," said Save the Children.
Hungry adults: Malnourished childhood found detrimental to later adult life
The report highlights that recent withdrawal of fuel price subsidy by the Nigerian government has pushed up food prices and could worsen the malnutrition crisis by making it difficult for many of the poorest children in the country to access basic food staples.
The report remarked a serious link between malnutrition and poverty, noting that poor children were twice more likely to be stunted and face tougher economic situations in later life.
It said adults who were malnourished as children earn at least 20% less than on average than those who were not.
An additional 2.4 million children could become physically and mentally stunted over the next 15 years, the group warned, adding that Nigeria may not meet 2015 deadlines on Millenium Development Goals regarding children if immediate steps are not taken to address hunger and malnutrition in women and children.
Seven countries are projected to see an increase in stunted children by 2015--the same deadline for the goals.
David Olayemi, the group's senior adviser on governance and policy, says malnutrition is beyond a social problem for families alone.
"If the family is unable to care of itself, then the country is in trouble," he noted.
"Most interventions being canvassed are simple. Exclusive breastfeeding costs nothing but we are not doing it."
Practical and affordable
The launch of the report comes shortly after the first ever nutrition summit held in Abuja in February.
Grant said the solutions required were "practical, available and affordable".
The group pledged to "prioritise nutrition in 2012 and beyond" through an ongoing project, Working to Improve Nutrition in Northern Nigeria (WINNN).
A partnership with Action Against Hunger and UNICEF, WINNN is a six-year project to scale up nutrition interventions targeting over six million children.
The project started last year in Jigawa and Zamfara and will expand to three other states this year.
Source: Daily Trust (Abuja, Nigeria)