www.checkbiotech.org ; www.raupp.info ; www.czu.cz

Researchers at the University of Nebraska and the Netherlands reviewed the
process for evaluating the potential risk of allergies in genetically
modified food crops, November 2005 by Annette Ryser, Checkbiotech.

Genetically modified (GM) crops may contain new proteins from other plants
or from bacteria, fungi and animals. While biotechnologists praise GM crops
for their excellent properties in agriculture, consumers would like to know
what there are going to eat.

One of the many questions regarding genetically engineered crops is the one
of allergenicity: Can the new introduced protein cause allergies in human
consumers, when they eat GM crops? Is it a so called allergen? If, for
instance, an allergenic protein from peanut were transferred into rice, then
those individuals who experience allergic reactions to peanuts could
unexpectedly react when consuming the modified rice. While the number of
individuals who experience severe food allergic reactions is relatively
small, it is important to protect the most susceptible people.


Minimizing the risk of food allergies
There is still no test that can predict with 100 percent certainty whether a
new protein might cause allergic reactions in a specific individual, or
whether introducing a new food to a child might cause allergies. However,
Dr. Richard E. Goodman from the University of Nebraska and colleagues
provide a comprehensive review in International Archives of Allergy and
Immunology on how GM crops can be evaluated to assess their potential
allergenic properties before being grown commercially. Dr. Goodman noted,?
Food produced from GM crops must be as safe as the unmodified varieties.?

Dr. Goodman recommends four general methods to identify proteins that would
present a high risk of causing food allergies with some individuals. This
process has been used to assess the potential allergenicity of all
commercially available GM crops in the US since 1996, with minor revision as
knowledge of food allergens and allergies have improved, as outlined in the
Codex Alimentarius Commission of the United Nations FAO in 2003.


Four different tests
1. All proteins consist of a sequence of molecules called amino acids. The
amino acid sequences of all known food allergens are listed in searchable
databases. If a new protein is going to be introduced into a food crop, its
amino acid sequence should first be compared with sequences from all known
allergens. If there is high similarity of the new protein with a protein
from the allergen database, further testing is necessary to either prove, or
disprove the potential allergenicity.

2. The new protein must also be tested for resistance to digestion by the
stomach enzyme, pepsin, in an acidic solution (pH1.2). This is an ideal
digestion assay that provides a good correlation for food allergens. It is
not meant to absolutely mimic digestion in all people. The more stable the
new protein is under these conditions, the more likely it is to cause food
allergies.

3. The specific allergic reactions experienced by most people happen because
their immune system produced IgE antibodies that bind to specific proteins.
Therefore, when a new protein is taken from a source that is a major
allergen, or when the sequence of the new protein is nearly identical to a
known allergen, blood samples (sera) from individuals with allergies to the
source or to the matched allergen are tested. The test is to determine
whether the IgE binds tightly to the new protein. If it does, there would be
an increased risk of allergy, if not, the risk is minimal.

4. In addition, the amount of the new protein in a GM crop must be analysed.
Many food allergens cause an allergic response when found in large amounts.
However, not all abundant proteins are allergenic. Abundance and resistance
to digestion by pepsin should be considered together.


Successful assessment of Brazil nut protein in soy
It can happen that during the pre-market testing a protein is recognized as
an allergen. Should this occur, Dr. Goodman?s message is clear ?the product
must not be commercially released - unless clearly proven to pose minimal
risk, or unless the product can be clearly segregated and labeled for the
allergic consumer.

There is one well documented case where a company introduced a gene from
Brazil nuts into soybeans to improve the nutritional quality. Antibodies
from some Brazil nut allergic individuals were tested and found to bind to
the protein. Therefore product development was cancelled. The assessment
worked, as that GM product was never consumed as food.

Dr. Goodman admonished, if this strategy is followed, the application of the
allergenicity assessment can greatly reduce the risk of introducing
allergenic proteins to food crops. The assessment should certainly always be
improved, going hand in hand with the increasing knowledge of the
experimental methods within the field of allergen testing. However, new
tests must be rigorously validated and demonstrated to be predictive.

?The process of specifically modifying single genes of food crops opens the
door to a wide variety of benefits,? said Dr. Goodman. So, considering the
great power of biotechnology, it is essential to keep it as safe as
possible.

www.checkbiotech.ch

------------------------------------------
Posted to Phorum via PhorumMail