April McCarthy, Prevent Disease
The tomato was one of the first commercially available genetically modified (GM) crops. In 1994, GM tomatoes hit the market in the US but have since disappeared. They’re about to make a come back at a grocery near you.
Earlier forms of this GM crop included the transgenic tomato (FlavrSavr) which had a “deactivated” gene. This meant that the tomato plant was no longer able to produce polygalacturonase, an enzyme involved in fruit softening. The premise was that tomatoes could be left to ripen on the vine and still have a long shelf life, thus allowing them to develop their full flavour. Normally, tomatoes are picked well before they are ripe and areÂ then ripened artificially.
These GM tomatoes, however, did not meet their expectations. Although they were approved in the US and several other countries, tomatoes with delayed ripening have disappeared from the market after peaking in 1998.
Today, tomatoes are being genetically modified to produce a peptide that mimics the actions of HDL cholesterol that biotechnology groups are promoting to supposedly reduce heart disease.
Led by Dr Alan Fogelman from the University of California, Los Angeles (UCLA), USA, his study found that consumption of GM tomatoes resulted in reductions of plaque build-up in arteries (atherosclerosis).
“To our knowledge this is the first example of a drug with these properties that has been produced in an edible plant and is biologically active when fed without any isolation or purification,” said Fogelman.
The rollout into major grocery retailers is expected, however no timeline has been established until more research is completed.
The UCLA team genetically engineered tomatoes to produce 6F — a small peptide that mimics the action of ApoA-1, which is the main protein of high density lipoprotein (HDL) or ‘good’ cholesterol.
Fogelman and his team fed the tomatoes to mice that lack the ability to remove low density lipoprotein (LDL) or cholesterol from their blood, and therefore develop inflammation and atherosclerosis when consuming a high-fat diet.
Similar gene modification techniques were devised in GM crops that led to tumors in a long-term widely publicized study on GM corn fed rats.
“The problem remains as with all GM techniques, that we simply don’t know what the long-term effects of consuming such foods will be since short-term studies can never tell us,” said researcher and geneticist Professor Thomas Tranter.
There are many other biotech projects aiming to enrich tomatoes with substances that may offer health benefits which claim to be more nutritious, however no human or long-term studies are planned to discover their effects on metabolism.
Monsanto developed tomatoes that delayed ripening by preventing the production of ethylene, a hormone that triggers ripening of fruit. Although the tomatoes were briefly tested in the marketplace, patent arguments forced its withdrawal.
Tomatoes (along with potatoes, bananas and other plants) are also being investigated as vehicles for delivering edible vaccines. Clinical trials have been conducted on mice using tomatoes that stimulate antibody production targeted to norovirus, hepatitis B, rabies, HIV and anthrax.
Korean scientists are looking at using the tomato to expressing a vaccine against Alzheimer’s disease. Hilary Koprowski, who was involved in the development of the polio vaccine, is leading a group of researchers in developing a tomato expressing a recombinant vaccine to SARS.
Although GM foods can only be planted in many countries as part of a trial, and even then only under strict conditions, millions of hectares of the crops have already been planted in the Americas.
Campaigners have warned that there is no compulsory labelling of meat or dairy products from animals which have been fed on GM crops, and that any long-term problems from eating the foods is still unknown.
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