Here is an interesting article suggesting, somewhat indirectly, that the amount of money needed to feed the world's poor is underestimated, primarily because it does not account for the needs of individuals to have diverse sources of nutrients (
article). As a result, the amount of money required to prevent absolute starvation is quite low, since it does not likely determine nutritional needs.
More than 20 million children suffer from severe, acute malnutrition in the developing world. Half of the 9.7 million deaths of children under five each year are caused by the condition, according to the World Health Organisation (WHO). It will cost $5 billion a year alone to feed children under the age of three in developing countries, MSF said.