GE food not more
allergenic than the counterparts
![](/IMG/298/47298/kamashwararao.gif)
Allergy is an abnormal state
of hypersensitivity of our body to normally innocuous substances in
food, medicine or the environment. Allergy is neither new nor
universal. It is not an infection that would spread. Each one of us
suffer from intolerance of, or allergic reactions to, one or the other
element in our environment or certain foods or drugs. Nevertheless,
there is no single substance that causes allergy to us. Allergies
affect millions of people and cause several deaths globally every
year.
Atmospheric pollen, dust mites, animal dander, insect stings,
molds, latex, cosmetics, fragrances and several others in a day-to-day
contact may cause reactions in people.
Walnuts, pecans, Brazil nuts, cashews, peanuts, soybeans, some
varieties of rice and wheat, cucumbers, mushrooms, fish, shellfish,
eggs, milk, mother’s milk, some vegetables and fruits, and
drugs like penicillin and aspirin, may cause intolerance or even true
allergy in certain individuals.
There have been cases where people have developed reactions to foods
they have been eating for decades. To some, this happened when they
shifted to a new place of residence, which did not revert when they
moved back to the old place, showing that environmental influences are
not necessarily the cause of the problem. But most allergies disappear
as mysteriously as they appear.
While there are no reliable data on food allergies in the developing
countries. In the US, five to eight percent of the children and one to
two percent of the adults are prone to true allergy from some kind
of food. Children as they grow may overcome their
sensitivities to certain food items, but the sensitivities acquired in
adulthood would not go easily. Therefore, such people have to avoid
food they are allergic to.
In a classroom comprising several children of diverse genetic
backgrounds but of the same age group, one or the other would be
sensitive to one or the other food item. Sensitivity to eggs, fish and
nuts is common. As children share their lunch at school, it
isn’t easy for parents to decide on what food they can pack
without risking sensitive reactions from any of their child’s
friends. The greater and unanticipated risk is from inadvertent or
accidental servings of offending foods.
In case of highly sensitive individuals, even 1/44,000 of a peanut
kernel may pose a threat to his/her life. Nevertheless, there
wasn’t any simmer of protest against marketing any of the
many conventional foods, which are established as severely allergenic
to certain individuals.
Risk of allergy from GE
crops
Risk of allergy from genetically engineered (GE) crops and food is
projected as a major biosafety issue, stemming from baseless
allegations.
A gene for the Brazil nut protein was introduced into soybean to
increase the content of methionine, an essential amino acid which the
human body does not synthesize. The serum from people allergic to
Brazil nuts cross-reacted with extracts of transgenic soybean and not
with extracts of its isogenic, which links the problem to Brazil nut
proteins and not the soybean. Though no one actually developed allergy
by eating the transgenic soybean which was never released for public
consumption, since the transgenic is likely to affect people who are
allergenic to Brazil nuts, Pioneer Hi-Bred International, the developer
of the product, did not proceed with it, an example of
self-regulation.
The Bt Cry 9c protein in the Aventis Starlink Bt corn controls the
European corn borer. Cry 9c protein binds to the
pest’s gut at a site different from that of the Cry 1
proteins, and so would be effective even if the pest develops some
resistance to Cry 1 proteins. Cry 9c protein was found to be
slightly more stable in simulated digestion than other Bt proteins, and
so it was thought that it might be allergenic. The United States
Department of Agriculture (USDA) cleared the Cry 9c transgenic corn for
use as both food and feed, but the US Environment Protection Agency
(EPA) took a precautionary measure and approved this corn only for
animal feed, as animals do not generally suffer from food allergies. Bt
Cry 9c protein was never demonstrated to be allergenic. The US Centers
for Disease Control (CDC) tested samples of blood from 17 people
claimed to have developed allergenic reactions to Starlink and found
that none of the blood samples showed cross-reactivity to Cry 9c
protein. The Cry 9c gene is not deployed in any commercial product
now. Since transgenic products approved as the only feed may
get into the food products, as has happened with Starlink Bt Cry 9c
corn that appeared in Taco Bell taco shells, no transgenic is now
approved exclusively for use as feed. This shows that the regulatory
regime is in fact vigilant.
Ignoring the scientific background of food allergies, and the fact that
the two questioned transgenes are neither allergenic nor deployed in
any product, these two cases are repeated
ad nauseam to make the world believe that all GE foods are allergenic
and to repeatedly demand a blanket ban on GE food. In India, the charge
was made against Bt cotton, though not a food crop. Even while
Bt brinjal is still in multi-location open–field
trials and not available for public consumption, it is being projected
as allergenic, trashing voluminous evidence that Cry 1Ac protein is not
allergenic which was also confirmed during biosafety testing on
Bt brinjal by Intox at Pune and Rallis at Bangalore.
Immunological basis of
allergy
The term allergy is used very loosely, and most people seem to have no
idea of what it actually implies. True, allergy involves the immune
system. Often food allergy is not differentiated from other types of
adverse non-immunological reactions to food. Since the public
fears allergy, it is being exploited to whip up fear against GE
food.
Mammalian systems produce four different classes of immunoglobulin
proteins (Ig), the antibodies, in response to the presence of hazardous
alien proteins (called antigens) that enter the body system through
food or pathogens. Vaccines contain antigens (of cholera or smallpox or
other pathogens) and vaccination prepares the body into producing
antibodies against specific pathogens. The antibodies bind to the
antigens when encountered in the body system affording the most
valuable means of our body’s defense.
The IgM antibodies form first, but both the quantity and importance of
the later formed IgG antibodies is far greater. IgG antibodies are the
most important body defense system. They bind to the antigens
neutralizing them. While IgA antibodies are specifically involved in
the defense of the oral cavity, the function of IgD antibodies is not
very clear.
For some poorly understood reasons, our immune system also produces
another class of antibodies, the IgE, in response to a few proteins,
which through a complex sequence of cascading biochemical events lead
to true allergic reactions, manifesting as skin rashes, intestinal
inflammation, cramps and diarrhoea or respiratory disorders. This
process is anaphylaxis, on record since 2641 BCE, which varies in
different individuals from mild and annoying to life threatening. The
active compounds, triggered by IgE involvement, such as histamine, are
mostly inflammatory agents that get into the blood stream making the
problem systemic when different areas of the body are affected at the
same time. Some similar reactions do not involve the IgE antibodies
(anaphylactoid reactions), but nonetheless cause health hazards.
Some non-protein compounds, like penicillin and aspirin, may also cause
severe reactions; these agents called haptens must bind to an
endogenous carrier protein to cause the
symptoms.
Diagnosis of allergy
Identifying an allergen is a long drawn process. For each individual,
list of suspected sources allergens is drawn and through a dermal prick
test, the possibilities are narrowed down by eliminating those that do
not cause any reaction at the test site on the skin. Identification of
the offending substance and demonstrating that it is true allergy
involving IgE antibodies is done through an enzyme-linked immunological
assay procedure.
Treatment of allergy
The best way to avoid allergy is to avoid contact with the allergen,
identified based on each individual’s
experience.
Repeated exposure to small quantities of an allergen over a long period
of time results in higher and higher titres of IgG antibodies, which in
course of time would be adequate to neutralize the allergen before it
had a chance to elicit IgE antibodies. This is how we overcome
allergies naturally, otherwise allergies are clinically treated
(immunotherapy). This slow process has worked well in treating
environment-based allergies, and its success has just been demonstrated
with peanuts on children who earlier developed strong reactions on
eating even small quantities.
While there is no assured treatment to cure allergies, anaphylactic
reactions are treated using anti-histamine or steroid drugs.
Allergenic potential of
foods
Protein that is degraded by the gastric enzymes before reaching the
intestine is very unlikely to cause allergy. This has been the basis to
investigate a protein further for its allergenic potential.
![](/IMG/299/47299/gmcropsbox2.gif)
Based on voluminous data on the biochemistry of over 200 known
allergenic proteins, tests have been developed to identify potential
food allergens. It is now understood that only certain short stretches
of amino acids (the components of proteins) constitute allergenic
sites. These identified sites, not the whole protein, trigger the
production of IgE antibodies. A consensus document on the biosafety of
Bt in crops (Organization for Economic Cooperation and Development,
July 2007), records that none of the Bt proteins deployed in crops,
including Cry 1Ac, Cry 1Ab, Cry 2Ab and Cry 9c, share similar amino
acid sequences with known proteinaceous food allergens. So far, no
allergenic reactions have been reported during extensive biosafety
tests on GE crops in several countries or on consumption of foods from
GE crops for more than a decade.
Transgenic crop varieties are substantially equivalent to their
isogenics, except for the protein coded by the transgene. The risk of
allergy needs to be considered when a GE food or drug contains new
protein(s), coded by the introduced genes, but not present in the
isogenic variety. For example, the Bt protein in the Bt
potato tuber is new. Now this protein is known to be safe for human
consumption. Similarly, the iron carrier protein ferritin, whose gene
from bean or soybean is being introduced into rice to enhance its iron
content, is not allergenic.
If a gene product in the non-transgenic (isogenic) variety were an
allergen, it would be so in the transgenic as well. Proteins that are
normally not allergenic will not suddenly become allergens in a
transgenic plant. Whether a particular protein is allergenic or not,
depends more on the consuming individuals rather than on the protein
itself. This makes identification of allergenic proteins quite tricky.
The remote possibility that Bt crop foods might sporadically cause
allergenic reactions in a few individuals, in spite of voluminous
evidence to the contrary, cannot be the reason to dump the whole
technology which is otherwise beneficial in a number of ways.
It is near impossible to test for all the antigens and haptens in a
product for the potential of allergy. Even so, scientists
have not been complacent and every new protein in a transgenic food or
feed is examined for allergenicity. In fact, among all the foods we
consume, the GE foods are the most thoroughly tested for allergenicity
and toxicity.
Concern for public safety is very essential, but spreading fear on
political compulsions and exploiting ignorance, is scare mongering.
What we need is a rational attitude with concern for the larger
benefits of the larger sections of the society, and not irrational
blanket bans on the entire technologies. No one ever said
that the production of any of the large number of conventional foods
known to cause severe allergies in a few people should be
stopped.