An apple a day keeps the allergist away ... or does it?

If an apple a day supposedly keeps the doctor away, what does it do to the allergist? Scientists may be able to genetically engineer apples that don’t trigger allergic reactions, but would people want to eat them?

While peanuts, egg and wheat might spring to mind when considering food allergies, apples probably don’t. But in fact, 75% of people allergic to birch pollen are also allergic to apples. This happens because a protein in the pollen, which causes an allergic reaction, is similar to a protein found in apples and some other fruit and vegetables. This issue is more common in regions with many birch trees, such as central and northern Europe.

These kinds of allergies can be difficult to identify. “Some people who are allergic may simply say they don’t like apples, since they’ve a very mild reaction after eating them,” explained Eric van de Weg, plant scientist at Wageningen University in the Netherlands, “but others will suffer blistering, problems catching their breadth and swollen lips, tongue and throat.

“We wanted to increase the low availability of hypoallergenic fruit but also come to a better understanding of the genes and proteins involved,” van de Weg said.

One solution trialled in a previous European project called ISAFRUIT was to genetically modify apples. This was done by gene silencing. Scientists tracked down the proteins that cause the allergic reactions and then switched off the responsible genes. “When you silence a gene you are not making any new protein, so this means the risks are lower,” van de Weg said.

Although the risks of producing GM apples may be low, the ISAFRUIT project found that the idea of GM fruit provoked heated debate. “Although consumers - and in particular food-allergic consumers - were more positive about the [GM] apple, there was still a clear preference for traditional breeding methods applied to the same end if possible, even for food allergic consumers,” said Lynn Frewer, an expert in risk communication at Newcastle University in the UK.

Nature itself may shed further light on this issue. “There are hundreds of apple varieties already available,” said Allessandro Botton, a plant geneticist at the University of Padova, Italy. For instance, it is known that apple varieties such as Golden Delicious and Granny Smith are part of the high-allergenic group, whereas Jonagold and Gloster induce only low-allergenic responses.

Botton, who worked on the genetics of fruit allergens in the project, says it is possible to focus on existing biological variability to look for low-allergenic apples and says the time is not yet right to think about gene silencing techniques. We must first understand the biological functions of these proteins, Botton says, adding that it is not certain what effect silencing genes might have on the plant’s health.

Geneticist Nina Fedoroff, from the King Abdullah University of Science and Technology in Saudi Arabia, says that public understanding of GM is “not generally sophisticated enough to make fine distinctions” between food that has been modified using other organisms’ genes and the type of genetic modification and gene silencing van de Weg is using.

“I don’t think the general views [of GM organisms] are all that different in the US and Europe, although the reasons given for being against GM are sometimes a bit different.”

“What is different in reality is that the pipeline hasn’t been completely closed off in the US by over-regulation, whereas it has in Europe. That is largely a consequence of the fact that all members of the EU have to agree on approval and just one member can keep approval from happening.

For now, van de Weg has no plans to grow his non-allergenic apples in Europe, despite having the potential to do so. We have enough basic knowledge to create non-allergenic apples, he says, but whether society is ready to embrace them is another issue.

Source: www.youris.com.