Is GM food safe to eat?

Doug Gurian-Sherman of the Union of Concerned Scientists on eating GM food in the USA. Source: Horizon © BBC Productions

Some experts fear that people will have allergic reactions to plants with added genes.

Genetically modified food has been on supermarket shelves around the world for 13 years. In America, around 80% of foods contain GM ingredients.

So far, there hasn't been a single reported case of illness from eating GM food. However, critics say there may be harmful long-term effects of eating GM.

Explore the arguments here. Can GM food create new allergies? Will it make us ill? Could GM food even modify our own genes?

Can GM food create new allergies?

After peanuts, brazil nuts are the most common trigger of nut allergies in the UK. Image: Jean Marconi Carvalho

Scientists transferring brazil nut genes into a soybean were concerned that people with nut allergies might react badly to the new bean. When they fed the soybeans to mice in 1996, they found the bean would trigger reactions in nut allergy sufferers. They abandoned their work on the soybean.

So, nut allergies can be set off by nut genes. Surprising? Maybe not. But a 2005 study revealed more worrying health effects of GM foods...

Tiny GM peas could create big allergies. Image: Mihai Simonia/iStockphoto

This study showed that even genes that are completely harmless in one plant can cause allergic reactions when transferred to another. Peas with added bean genes triggered reactions in mice, even though the mice weren't allergic to the peas or the beans.

Also, after eating their diet of modified peas, the mice started having allergic reactions to other foods such as egg white, which had not affected them before.

It turned out the mice reacted differently to the gene when it was transferred to peas.

In 1998 a study that looked at how rats were affected by eating GM potatoes turned out to be controversial. Image: Sergey A Pristyazhnyuk/Fotolia.com

Will GM food make me ill?

When these allergies were discovered, scientists stopped working on the new crops. But GM critics fear a diet of modified genes carries other health risks too.

In 1998 scientist Arpad Pusztai was asked by the UK government to test the effect of GM foods on animals. He found that rats fed a kind of GM potato suffered gut damage. The publication of these results in a top medical journal raised massive public concern in the UK about the possible dangers of eating GM food.

But not everyone agreed with Pusztai...

Pusztai's work became the subject of controversy when some scientists claimed his experiments hadn't been repeated enough or properly controlled. Pusztai eventually lost his job over the matter, but maintains his results are valid.

The journal that published his study said the experiments should be repeated to see if his results were right – but ten years on, this still hasn't been done.

To date, there haven't been any reports of long-term effects of eating GM foods. Is this because GM food is safe – or because its effects haven't been fully researched?

Could GM food modify me?

If cows are fed with GM products, are we drinking GM milk?

Most experts don't believe modified genes can 'escape' into our own bodies, let alone change our own genetic code. A 2007 study on animals fed with GM food supports this view. No evidence of modified genes was found in the animals' bodies, or in their milk or meat.

We eat genes all the time. All food contains them, although most are destroyed during food manufacture and cooking. What we do eat – between 0.1 g and 1 g of genetic material each day – mostly gets broken down in our gut.

However, a small amount survives...

A little genetic material does remain in our digestive system – in the helpful bacteria that aid our digestion. A 2004 study of the guts of human volunteers fed GM food found traces of modified genes in these bacteria. GM critics are concerned that modified genes can escape from food so easily.

Others feel this isn't cause for concern. Bacteria and other microbes exchange genetic material all the time. It isn't only modified genes that move around, but genes from all kinds of food and from other microbes.

Regulation, regulation, regulation

GM food? In the USA, GM products are not labelled.

So far, there is little evidence that today's GM foods are harmful to health. However, the possibility of new allergies means we must not ignore the potential risks.

Food safety regulations vary around the world. In Europe GM food has to pass strict tests before it is licensed. This reduces the risk of a harmful product being sold. Some people even think the extra testing makes modified food safer than other foods. However, in America food modified with genes from the same or similar species does not have to be tested.