Global food supply may not meet the demands of the rising population in agriculturally-poor countries, according to a University of Virginia study. The researchers said that the effect will be predominantly observed in arid to semi-arid regions like Africa's Sahel that depends on imports for majority of their food supply.

For the study, the researchers used production and trade data for agricultural food commodities collected by the United Nations' Food and Agriculture Organization. They then recreated the global food network in terms of food calories transacted among countries.

The researchers found that most of Africa and the Middle East are not self-reliant, but trade has enhanced access to food in the Middle East and in the Sahel region. However, the trade has not eliminated food insufficiency in sub-Saharan Africa and central Asia.

"We found that, in the period between 1986 and 2009, the amount of food that is traded has more than doubled and the global food network has become 50 percent more interconnected," said Paolo D'Odorico, a U.Va. professor of environmental sciences and the study's lead author, in a press release. "International food trade now accounts for 23 percent of global food production, much of that production moving from agriculturally rich countries to poorer ones."

"Overall, in the last two decades there has been an increase in the number of trade-dependent countries that reach sufficiency through their reliance on trade," D'Odorico said.

D'Odorico said that these trade-dependent countries, however, may become more susceptible during food shortage periods. For example, the governments of Russia, Ukraine and the United States banned or limited food exports in 2008 and in 2011 due to drought conditions as a result of extreme climate events. This triggered food crisis and caused anxiety in trade-dependent countries.

The study also found that 13 agricultural products - wheat, soybean, palm oil, maize, sugars and others - constitute 80 percent of the world's diet and food trade. Plus, there was an increase in consumption of meat in China. Meat production requires significantly more land area than crops.

"Fats and proteins tend to increase with the economic development of emerging countries," D'Odorico said. "An increase in consumption of animal products is further enhancing the human pressure on croplands and rangelands."

The finding is published in the American Geophysical Union journal.