Raw chicken Copyrighted image Credit: BBC

With the increasing globalisation of the food trade, market stalls, grocers and supermarkets now offer us a bewildering choice of affordable products. But the food we eat has often travelled thousands of kilometres and passed through scores of hands to get to our plates. So can we be sure where it's been and what's happened to it in the meantime? This week's Big Question with Emma Joseph is: Can we trust what we eat?

Felipe Fernandez Armesto Copyrighted image Credit: Used with permission "One needs to be quite sceptical and extremely careful about the health of our food, not because we need regulation, but because where it's produced far from the consumer, there is no community control on the producers to produce good food", says Felipe Fernandez Armesto, Professor of Global Environmental History at Queen Mary College, in London. As food has become increasingly mass-produced, says Professor Armesto, its cost may have been reduced, but so has its quality.

So how safe is the food we eat?

"The incidence of food-borne diseases has clearly been going up", says Jorgen Schlundt, director of the Food Safety Department at the World Health Organisation.

"In all parts of the world a lot of people everyday get sick and even die from unsafe food. In the developed countries it's estimated that one third of the population every year gets a diarrhoea case from micro-organisms in food. In developing countries this number is probably a lot higher."

Food contaminated by harmful micro-organisms can cause diseases like diarrhoea as well as other illnesses affecting the joints, the liver and other organs. It kills some 2 million people every year.

The most common bacteria found in food (usually poultry and eggs) is Salmonella, which causes salmonellosis. It is killed by the heat when the food is cooked.

Why are there more cases of food poisoning?

There are many explanations, says Jorgen Schlundt.

"We've had changes in the production system, there are very big herds now, which means that the bacteria can spread more quickly. There are issues about how we treat our food ourselves in the kitchen, issues about the long food chain and things that happen in slaughterhouses, issues about the change in our population… and all of these things could have some influence in how we get the bacteria into our bodies."

So how can we protect ourselves?

"What you can really do at home is rinse your food to take out some of the chemicals that might be there, and make sure that you heat treat everything. Don't mix what you have cooked with anything that's raw", advises Mr Schlundt.

How can we know where our food has been?

Michiel Korthals Copyrighted image Credit: Used with permission "A piece of meat or chicken that we buy already packed in the supermarket is likely to have passed at least ten stages before reaching the shelves", says Michiel Korthals, Professor of Food Ethics at Wageningen University, in Holland. And, he says, something can go wrong at every one of those stages.

The movement of food from the fields to the plate is often referred to as the "food chain" - and today, the food chain is longer than ever. But Professor Korthals is sceptical about the term itself. "It is rather optimistic, because it sounds as if the whole food business is organised very well, like a chain with links. But that's not the case. It looks more like several plates of pasta with very unclear ways of supplying and transporting food. It's one big mess," he says.

So, how do we know what is in our food?

To protect the health of consumers, 170 countries have made a commitment to stick to food standards set down under international treaties -- known as the Codex Alimentarius. The Codex covers issues like the nutritional quality of food, additives, contaminants and labelling.

"By law, in Europe, the label has to be accurate," says Tim Lang, professor of Food Policy at the City University in London. The labels show the nutritional breakdown of a product, with the biggest ingredient first.

So, do we trust it?

Tim Lang Copyrighted image Credit: Used with permission "Trust in food goes up and down," says Tim Lang. "It dropped dramatically in Britain over the period of the food scandals. It began over additives, in the late '70s. Most additives were purely cosmetic, they served no function, just made the food look ok. But in the case of a colouring for yellow, tartrazine, it became a very big issue, because it was associated with hyper-activity."

Concerns over "Mad Cow disease clearly hit the public. But BSE wasn't deliberately put into food. It raised the whole question about the methods of production -- had the intensive production system put in place since the '60s really got out of control? It became a deeply philosophical issue that went way beyond additives and contaminants."