New study provides evidence of gut damage caused by transgenic Bt corn

New study provides evidence of gut damage caused by transgenic Bt corn

Contrary to what is claimed many times, there is no scientific consensus or certainty regarding the safety of GM foods. Even the report from the US National Academy of Sciences, which was once wielded as the definitive proof that "science" gave them the go-ahead, says that you can't make "umbrella" claims about food safety. transgenic. He adds that, although the data collected so far do not allow to affirm emphatically that there are genetically modified foods that are harmful to health, the studies carried out have not used methodologies to rule out these effects either: he also points out the scarcity of long-term studies and the lack of follow-up of those studies that have found evidence of damage (click here to read our comments on the report, and here for a list of examples of studies that have found evidence of damage).

This other study has recently been published which, once again, does not make it possible to affirm categorically that transgenic food (in this case a type of Bt corn) causes damage to the digestive system of rats, but which certainly provides alarming data that should be investigated further. As indicated in the article that comments on the study, there are some elements of the methodology that should be corrected when approaching these new investigations.

Title: Monsanto's MON810 GMO Corn Damages Rat Gut - New Study Source: GMWatch Author: Claire Robinson
Link: http: //…
Date: Thursday, November 24, 2016

Rats fed Bt MON810 transgenic corn for just 90 days suffered severe damage to the mucous membrane of the jejunum (part of the small intestine), according to a new study.1
The type of maize consumed by the rats was MON810: Ajeeb YG, a transgenic version of Ajeeb, a variety of maize adapted to the growing conditions of Egypt. The GMO-fed rats consumed a diet containing 30% MON810: Ajeeb YG corn, while the control group rats consumed the same amount of non-GMO corn.
In the group of rats fed the transgenic feed, some areas of the intestinal villi - finger-shaped structures that absorb nutrients from food - were damaged. They had lost relief and their structure had been modified, and some of their cells formed blocks. The damage is clearly visible in the images included in the study. The crypts (intestinal glands) had suffered alterations, and the congestion of the blood vessels was appreciated. Signs of inflammation - infiltration of white blood cells were observed around the damaged areas. Furthermore, the cells of the intestinal epithelium had an abnormal structure.
Other signs of damage included increased mucosal cell shedding, increased numbers of mucosal-secreting goblet cells, and increased rates of cell division in the lining of the crypts.
The study, carried out by physician Marwa Ibrahim and Ebtsam Okasha, from the Faculty of Medicine of the University of Tanta in Egypt, has been published by the journal Experimental and Toxicologic Pathology (see abstract below).
The researchers conclude that "the consumption of transgenic corn profoundly alters the histological [microscopic] structure of the jejunum." They add, "The results of this study could show that, despite reassuring claims about GM products, GM corn profoundly alters the histological structure of the jejunum mucosa at various levels. Several alarming data have been revealed, including the Proliferative and hemorrhagic lesions in addition to several ultrastructural alterations described for the first time in the jejunum in animals that have consumed transgenic corn. "
The researchers urge new studies to clarify the mechanisms by which MON810: Ajeeb YG maize exerts this effect. Possible mechanisms include direct damage to the jejunum mucosa by the Bt toxin (Cry1Ab) present in transgenic corn, similar to what occurs in the intestine of target pests, or an indirect effect due to the alteration of the intestinal microbiota. Either of the two could produce the changes observed in the structure of the intestinal mucosa.

What does this study tell us?

The data obtained by this study are dramatic and significant. However, it is necessary to point out certain limitations. Among these is the fact that the control maize used was not the isogenic non-transgenic parent variety (Ajeeb), but an unidentified non-transgenic maize used for the formulation of standard laboratory diets.2
Furthermore, the presence of toxic contaminants such as mycotoxins or pesticide residues in different diets has not been evaluated.2 Both types of contamination could cause harm.
For these reasons, it is not possible to definitively attribute the damage suffered by rats fed transgenic feed to the process of transgenesis, including the Bt toxin. However, the data provide strong reasons to think that this could be the case. It is especially relevant to place this study in the context of other previous studies that observed toxic effects derived from the consumption of the same MON810: Ajeeb YG transgenic corn.

Previous studies

Two other rat feeding studies conducted by Egyptian scientists on the same transgenic maize, MON810: Ajeeb YG, observed damage in animals fed transgenic feed. In these cases the comparator was the appropriate isogenic variety, Ajeeb, so the adverse effects observed in rats were clearly due to the inserted transgene.
In the first study, rats fed MON810: Ajeeb YG maize for 45 and 91 days showed differences in body and organ weight and blood biochemistry when compared to rats fed the non-transgenic parental variety Ajeeb grown in the same conditions. The authors noted that the changes could indicate "potential toxic / adverse health effects", which needed further investigation.3
In the second study, the same group of researchers collected histopathological (microscopic) data revealing multi-organ toxic effects in rats fed the MON810: Ajeeb YG transgenic corn for 91 days. Some of these effects were abnormalities and fatty degeneration of liver cells, congestion of blood vessels in the kidney, and overgrowth and necrosis (death) of intestinal villi. When examining the testicles, necrosis and desquamation (shedding) of spermatogon cells appeared, which are the basis of sperm and therefore male fertility.4
Significantly, the data obtained in the second study, that is, cellular abnormalities, blood vessel congestion, and damage to the intestinal villi also appear in the new study by Ibrahim and Okasha.

The correct comparator

For researchers it may be difficult or even impossible to access the appropriate materials to carry out a feeding study in animals with transgenic crops, specifically the transgenic variety to be investigated and the non-transgenic parental variety grown under the same conditions. This is because often companies developing GMOs have not made these materials available to independent researchers.5
However, the fact that the first two Egyptian studies did use the correct comparator suggests that, in theory at least, it should be possible for other researchers to access the non-transgenic parent variety, Ajeeb, as the correct comparator to use in any study. on MON810 corn: Ajeeb YG.

Rats fed transgenic feed did not show clear signs of disease

Ibrahim and Okasha noted that rats fed transgenic feed did not show clear signs of disease or behavioral disturbance. This is perhaps not very surprising, given the relatively short duration (90 days) of the study. However, the animals were sick, as revealed by histopathological examination of the intestinal tissue, and the data clearly indicate that a long-term feeding study with a duration of 2 years or more should be carried out to check whether damage to the found intestinal mucosa would at some point become a clearly noticeable disease.
Furthermore, the results of this study are a clear sign that all animal feeding studies with transgenic foods used to justify their authorization should include histopathological data. At present this is not a required or routine practice.

The European Commission wants MON810 maize to be grown in Europe

This new study comes at a time when the European Commission is trying to get the MON810 maize crop in Europe approved in time for the 2017 season. It is also considering two other types of insecticidal transgenic maize, Dupont Pioneer 1507 maize and Syngenta's Bt11 corn. EU member states are expected to vote on December 9. *

However, all the data regarding MON810 maize suggest that it should not be grown on a larger scale, but rather should be withdrawn from the market. And all transgenic crops should be properly tested before being marketed. This includes detailed studies of so-called "omics", analyzes that can reveal unforeseen changes in the expression of proteins and other metabolites, as well as long-term feeding trials in animals.

Update 24 November 2016, 16:35 GMT: The vote on the authorization of cultivation of the three varieties of transgenic maize in Europe has been postponed again to January 17, 2017.

  • 1. Ibrahim MAA, Okasha EF. Effect of genetically modified corn on the jejunal mucosa of adult male albino rat. Experimental and Toxicologic Pathology 2016; 68 (2016): 579–588. Here
  • 2. a. b. Communication with the authors via email.
  • 3. Gab-Alla AA, El-Shamei ZS, Shatta AA, Moussa EA, Rayan AM. Morphological and biochemical changes in male rats fed on genetically modified corn (Ajeeb YG). J Am Sci. 2012; 8 (9): 1117–1123.
  • 4. El-Shamei ZS, Gab-Alla AA, Shatta AA, Moussa EA, Rayan AM. Histopathological changes in some organs of male rats fed on genetically modified corn (Ajeeb YG). 2012; 8 (10): 684–696.
  • 5. Waltz E. Under wraps - Are the crop industry’s strong-arm tactics and close-fisted attitude to sharing seeds holding back independent research and undermining public acceptance of transgenic crops? Nature Biotechnology 2009; 27 (10): 880–882. Here

Effect of genetically modified corn on the jejunum mucosa of adult male albino rats By Ibrahim MA

Genetically modified (GM) plants expressing insecticidal traits provide a new strategy for crop protection. This transgenic corn contains Bacillus thuringiensis (Bt) genes that produce delta endotoxins throughout the plant. Diet can influence the characteristics of the gastrointestinal tract, altering its function and structure. The objective of this study is to evaluate the effect of transgenic corn on the histological structure of the jejunum mucosa in adult male albino rats using different histological, immunohistochemical and morphometric methods. Twenty adult male albino rats divided into two equal groups were used: control group and group fed transgenic corn, to which a diet with 30% transgenic corn was administered for 90 days. The jejunum samples were processed for observation under the light and electron microscope. Antibodies against proliferating cell nuclear antigen (PCNA) were used for immunohistochemical studies. Different morphometric parameters were evaluated. The samples from the group fed genetically modified corn showed different types of structural changes. Focal destruction and loss of villi was observed, leaving the mucosal surface bare, alternated with stratified areas, while some crypts appeared completely altered. The presence of congested blood capillaries was detected, as well as focal infiltration by mononucleated cells. An increase in the expression of PCNA and the number of goblet cells was also observed, as well as a significant increase in the height of the villi and the depth of the crypts. Remarkable ultrastructural changes have also been recorded in some enterocytes, with focal loss in the microvilli. Some enterocytes had vacuolated cytoplasm, swollen mitochondria with altered ridges, and a dilated rough endoplasmic reticulum (rER). Some cells had dark and irregular nuclei, with abnormal condensation of chromatin. It could be concluded that the consumption of transgenic corn profoundly alters the histological structure of the jejunum.

Image: Ed Uthman

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Video: Why Genetically Engineered Foods Should be Labeled: Gary Hirshberg at TEDxManhattan 2013 (June 2021).