Prices city by city
So how hard are people being hit by the world food crisis?
Official statistics can be weeks or months out of date, so BBC World Service is calling on its global network of reporters to keep you in the picture week by week.
The price index is tracking food prices in eight major cities. 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 normalised 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. Check the individual city pages for details of each food 'basket'.
This is how the index currently looks: