Ever Wondered About... GM food?

Used with permission

Mention genetic engineering to your average Brit, and they’ll probably look very disapproving. When the UK government started farm scale trials of genetically modified crops they were met with protest. The environmentalists’ message struck a cord with the British public. Yet GM technology promised to make food more nutritious, wholesome, and safely produced. As with food additives, manufacturers had already had to convince legislators their products were safe. They had conducted scientific tests for toxicity, capacity to cause allergies, and risk of cancer. So why worry? It comes down to something very deep-rooted in the way different people see the world, and equally different interpretations of what actually happens when we eat GM food.

Did you know ... ?
In 1999 there were 2,000 processed foods containing GM ingredients in British supermarkets. In 2000, after public opposition, only 100 remained.

Genetic Engineering
In conventional plant breeding, a plant with one set of desirable characteristics is crossed with a plant with another set of desirable characteristics, in the hope that some of the offspring will have the benefit of both. In genetic engineering, scientists take advantage of their vast knowledge of what genes do, in order to take a single gene from one organism and transfer it into another. It is possible to cross traditional boundaries of species, for example, by putting a gene for antifreeze properties from an arctic fish into a strawberry, to make a frost-resistant plant. In the Bt potato, scientists take a gene for insect resistance from a bacterium and engineer it into a potato.

Did you know ... ?
Farmers have been selectively breeding crops for 10,000 years

Bt potato
This is a GM product where, in a sense, the organic farmers got there first. For 40 years, organic farmers have been spraying crops with a bacterium, Bacillus thuringiensis, that is poisonous to insects. This is a biological phenomenon, so the spray doesn’t class as a pesticide and doesn't threaten organic status. When genetic engineers studied the bacterium, they were able to isolate the gene that produces the active ingredient. They took this gene and engineered it into maize, cotton, and potato. That way, the plants have 24-hour protection from damaging insect pests like the pink bollworm. But perhaps ironically, no organic farmer would dream of planting it.

Did you know ... ?
Bt crops are right across the United States

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 GM Food and Toxicity Testing

Typical laboratory toxicity tests for a GM protein include tests for chemical analysis, heat stability, and what happens when doses some 1,000 times greater than a human would consume are fed to mice. The protein is put through a simulation of digestion to simulate whether it can cause allergies. The quicker the protein is digested, the more reassuring the result, since a key characteristic of many known allergens is that they resist digestion in the gut. Finally, the biotech companies have to prove to regulators that the protein doesn’t interact with the plant’s own proteins and alter the chemistry of the plant itself. This involves pinning down the entire chemical composition of the GM plant, and comparing it with that of a conventional one.

Did you know … ?
A single human cell is a hundredth of a millimetre in diameter and contains 2 metres of DNA

GM Food and Allergies

Nut allergy sufferers in the US have something to thank the federal testing system for. During the early stages of R&D for a new GM product, a gene from a Brazil nut was engineered into soya to make it more nutritious. During testing, scientists discovered that the protein brought nut allergy as an unwanted side effect. Testing stopped and the product was abandoned. This episode helped to convince regulators that the laboratory testing system, established by scientists to weed out potential problems, works. But others are not so sure.

The GM scientist’s view:
"There was a hypothetical avenue by which one of the Bt proteins might cause allergies and there was a big scare about it last year, but there was when all of the people who though they’d become allergic were analysed they had no antibodies in their system to this protein at all, and no body has ever been identified as having antibodies to any engineered protein as far as I’m aware."
Professor Jonathon Jones works at the John Innes Centre in Norwich. His work is on how to prevent crops from succumbing to disease.

The anti-GM protester’s view:
"BSE was caused by a tiny little change in the way meat is produced, and it led to a complete disaster, and so consumers have definitely got a right because GM could have all sorts of properties which could affect peoples’ digestion, peoples’ allergies, that sort of thing."
Jenny Samson is an active member of several environmental groups, organising protest campaigns against GM.

Did you know ... ?
Vegetarian cheese is made possible by the genetic manipulation of yeast.

Production team
 GM Food and Risk of Cancer

Testing for ability to cause tumours is a matter of assessing risks. It is possible to first guess whether there is any chance a chemical might be carcinogenic by looking at its chemical structure. But the risk doesn’t stop there. It is also important to get additional data about the substances the protein may be broken down to in the body (metabolites) which might also be potential carcinogens. Where there is thought to be a possibility of cancer, testing is usually done over a couple of years, feeding the highest possible doses to laboratory rodents.

Did you know ... ?
When used as an organic pest control, US authorities did not require Bt protein to go through carcinogenicity tests

What happens when we eat GM food?

Supposing we eat a chip made from a Bt potato. Below is what basic science would predict. Remember, this GM potato differs from a conventional potato by only one gene, which encodes a protein for insect-resistance.

Mouth: the chip is chewed to break it up mechanically. Enzymic digestion of the carbohydrate begins. Assuming Bt potatoes differ from conventional ones only by a protein, the digestion process here must be identical to that in a conventional potato.

Stomach: acid breaks food down chemically. Enzymic digestion of protein begins. If the human body has enzymes capable of targeting Bt protein, it starts to break down. If not, the protein will pass through to the small intestine, eventually to be eliminated in faeces.

Pancreas: secretes enzymes for the digestion of nucleic acids (DNA and RNA) into the digestive tract. Downstream of here the Bt gene itself, and its associated RNA’s, will start breaking down.

Small intestine: Fat is digested here, and digestion continues for carbohydrates, proteins and nucleic acids. If the body has enzymes capable of targeting Bt protein, it will break right down. If not, the protein will pass through to large intestine elimination in faeces.

Large intestine: material reaching here is of little use to the body - water is absorbed and it is compacted into faeces. Whatever’s left of the Bt proteins and nucleic acids pass through here and out of the body in faeces.

So ... is this what actually happens in the real world? Well, that depends on who you ask...

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 What does happen when you eat chips made from a Bt potato?

A pro-GM scientist may say: The only difference from a conventional potato is in the DNA/RNA and the protein it codes for.

An anti-GM scientist may say: Genetic engineering is so complex it’s impossible to guarantee the absence of other biochemical permutations.

A pro-GM scientist may say: The protein is broken down in the stomach and small intestine.

An anti-GM scientist may say: The protein may not be broken down and may cause allergies (as have been observed with Bt spray).

A pro-GM scientist may say: The DNA is quickly broken down in the small intestine.

An anti-GM scientist may say: The DNA may hang around long enough to get into the bloodstream or bacteria in the gut.

A pro-GM scientist may say: The consequences are predictable.

An anti-GM scientist may say: The consequences are unpredictable.

There is rarely any such thing as total scientific consensus. Even among scientists, there are different interpretation of the available data. Both camps will draw upon scientific evidence to support their positions. So there must be something even more basic than science that is motivating their reading of the evidence – a fundamental difference in their underlying world views.

Did you know ... ?
Your alimentary canal is four or five times longer than you are tall.

So, what are the opposing views regarding GM food?

The GM scientist’s view:
"Well any change has consequences, I mean you could say exactly the same argument about mobile phones or any new technology, but you have to be realistic about what can happen. If you’re gonna make a criticism of some new technology you have to come up with a plausible mechanism by which it could cause some damage and these guys just haven’t."
Professor Jonathon Jones works at the John Innes Centre in Norwich. His work is on how to prevent crops from succumbing to disease.

The anti-GM protester’s view:
"What’s going to happen if soil bacteria eats a piece of GM crop pollen or if the pollinating insects eat it, or cross pollinate it with another species? We could get superweeds, we could have poisons in the food chain, anything could happen as a result of the GM crop cross pollinating and escaping into the environment."
Jenny Samson is an active member of several environmental groups, organising protest campaigns against GM.