UN Secretary General Ban Ki-moon has said he is deeply concerned about the sharp rise in global food prices.
Rising prices have hit many poor people across the globe
Mr Ban said the trend would hinder progress towards the millennium development goals (MDGs), which aim to halve extreme poverty by 2015.
The UN World Food Program (WFP) and other agencies may be forced to ration food aid, he said in a BBC interview.
He said shortages might be eased by a "green revolution" to transform farming methods in Africa.
Global food prices have risen by 40% in nine months and food reserves are at their lowest for 30 years.
The WFP is facing a $500m (£248m) shortfall in its attempts to feed 73 million people this year.
Mr Ban said that "many countries in particular in Africa they now have to pay double or triple the price for their bread," and warned that this would lead to increased malnutrition.
"This will all affect our MDG programmes - I am very much seriously concerned about this," he said.
The change has been blamed on poor harvests, population growth, rising energy and grain prices, the effects of climate change, and a shift to biofuel crops.
Although one UN official has called the increasing use of crops for fuel rather than food a crime against humanity, Mr Ban said there was a need to balance the positive and negative aspects of biofuels.
Among possible solutions, he said that "there is broad consensus that more resources should be provided to help an African green revolution".
But he cautioned that transforming commitments into action would be a "huge political challenge".
"We need to rededicate and commit ourselves by galvanising political will, by mobilising necessary recourses."