Food security has become an important issue for many countries
The issue of food security has become a key issue for many governments and organisations in recent months.
There have been riots, price controls and bans on the export of staple foodstuffs such as rice, as governments have sought to maintain a stable supply of food
Yet official data on food prices is often months out of date, so in this real-time experiment, the BBC is using its global network of reporters to monitor food prices in cities around the world.
Since July 2008, BBC reporters have been monitoring food prices in seven cities for the BBC's World Food Price Index.
Each week our reporters head to the shops and record the prices for five of that country's staple foods. Every basket of goods has been set to a cost of 100 in the first week of this experiment.
How much it would cost to buy the same basket in later weeks is then reflected in the rise or dip above or below 100.
Reflecting the growing importance of food security, the United Nations has set up a task force headed by UN secretary general Bang Ki-moon.
Its aim is to promote a unified response from global agencies to the challenge of achieving world food security.
Nearly two-thirds (60%) of people in a 26-nation poll commissioned by the BBC World Service last year said they had been feeling the burden of recent rises in the cost of food and energy.
They said that the rising cost of food, fuel and electricity has affected them and their family "a great deal".
The survey found that many people, especially in the developing world are cutting back on what they eat because food is more expensive.
Most people were not satisfied with what their governments have done to contain the problem. There were very high levels of dissatisfaction in both developed and developing countries.
The figure was more than 80% in Egypt, the Philippines and Lebanon, and more than 70% in France and Italy.
The survey questioned a total of more than 27,000 people in 26 countries. It was conducted by the international polling firm GlobeScan, together with the Program on International Policy Attitudes (PIPA) at the University of Maryland.