3-Food: COMMENT on soya and food allergy
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- Subject: 3-Food: COMMENT on soya and food allergy
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- Date: Wed, 31 Mar 99 19:33:58 +0100
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This is a response to the mail from Huib de Vriend on the York
Nutritional Laboratory press release on allergies (GENET-news: Soya and
food allergy, March 17).
The fact remains that a strong (50%) increase in oversensitivity response
to soy has been found. Of course the big questions is: what causes this?
There are three possible options:
1) the new protein in soy is allergenic.
2) the herbicide glyfosate residues are causing reactions.
3) people eat more soy.
Nr 1 and 2 are both possible.
Nr.1) The basic questions on the allergenicity have never been fully
answered. From my work with seeds I have looked intensively at the safety
assessment from Monsanto on the new protein. The conclusion was that the
new protein is a potential allergenic and that Monsanto came with the
wrong and untenable statements. Besides this, the new protein can change
in the food processing industry. During heating it may bind to sugars and
become a more stable allergenic. This would also change the protein so it
may not be recognised anymore. I don't think that this is thought about
in the labelling regime.
For the protein's allerginicity potential there are the following points:
Monsanto's safety-assesments (not proof!) when the soy was introduced was
The CP4EPSPS protein is expected not be dangerous because:
a: the protein is rapidly digested in vitro
b: the protein shows no glycosylation
c: the protein has a molecular weight of 47.5 kDA
d: the protein is not acutely toxic to mice
ad a: Following text comes from Dr. Kamsteeg, a biochemist working in the
field of allergenicity.
"Only by digestion a protein sometimes can become allergenic. Also
cooking or heating can sometimes be a necessity. In the heating of
proteins with sugars considerably more stable allergenics can be formed
by N-glycosidial binding of sugars (glycosides) to proteins.These
allergenics are very resistant to digestion, but they are also not
identical to the basic protein. Also in these cases a person may for
example in a skintest not react to milk but a strong and fierce reaction
may appear after the drinking of sterilised coffeemilk. Most allergenics
have a molecular weight of 20.000 Dalton (20kDa). It is thought that
proteins with a higher molecular weight form an allergenic only after
breakdown in the digestive tract".
In this context the recent report of the EU Scientific Commitee on Plants
is also very relevant. They say: "The use of in vitro simulation of
gastric and intestinal digestion of the gene product should be
considered supplementary to in vivo experiments designed to measure the
survival of the gene products when fed to animals as an integral part of
the GM plant. Isolated proteins are known which are fully degraded in the
simulated gastric system but survive gut passage intact when fed as part
of a normal diet" (SCP: outcome of discussion 31 par.3.4.4, 18 december
ad b: the fact that the protein shows no glycosylation does not mean so
much. Bacterial proteins do not express glycosylation, but the binding
may happen during food processing.
ad c:the molecular weight places it in the category of proteins which are
thought to become allergenic AFTER digestion. Molecular weight is seen as
more important for allergenic potential than glycosylation.
ad d: the toxicity issue is actually another issue and of course at least
as important. A full critique on the toxicity assesment I could give you
The CP4EPSPS protein in soy is for 74% different from the normal soy
protein. Since these proteins are plant-bacterial mixes, they are truly
new proteins and cannot be compared to either plant or bacterial proteins.
Nr.2) The tolerance level for glyphosate residues has been increased from
0,2 mg/kg bodyweight to 20 mg/kg bodyweight where there, by my knowledge,
is no change in insights about the toxicity, which was the reason to
establish it at 0,2 mg/kg bodyweight. A 100 fold increase!! Health
protection services are the national organs to control residue levels on
foods, at least for Holland this is true. Problem is that this research
is not being done extensively.
Nr. 3 is the least likely because it seems not likely that people are
eating more soy especially not since industry is replacing soy in a
rather significant number of products.
Wytze de Lange
- Dutch Genetech Platform -
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-| The European NGO Network on Genetic Engineering
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