---
title: "Genetically modified food controversies"
chunk: 9/21
source: "https://en.wikipedia.org/wiki/Genetically_modified_food_controversies"
category: "reference"
tags: "science, encyclopedia"
date_saved: "2026-05-05T04:17:47.717639+00:00"
instance: "kb-cron"
---

=== Animal feeding studies ===
Reviews of animal feeding studies mostly found no effects. A 2014 review found that the performance of animals fed GM feed was similar to that of animals fed "isogenic non-GE crop lines". A 2012 review of 12 long-term studies and 12 multigenerational studies conducted by public research laboratories concluded that none had discovered any safety problems linked to consumption of GM food. A 2009 review by Magaña-Gómez found that although most studies concluded that modified foods do not differ in nutrition or cause toxic effects in animals, some did report adverse changes at a cellular level caused by specific modified foods. The review concluded that "More scientific effort and investigation is needed to ensure that consumption of GM foods is not likely to provoke any form of health problem". Dona and Arvanitoyannis' 2009 review concluded that "results of most studies with GM foods indicate that they may cause some common toxic effects such as hepatic, pancreatic, renal, or reproductive effects and may alter the hematological, biochemical, and immunologic parameters". Reactions to this review in 2009 and 2010 noted that Dona and Arvanitoyannis had concentrated on articles with an anti-modification bias that were refuted in peer-reviewed articles elsewhere. Flachowsky concluded in a 2005 review that food with a one-gene modification were similar in nutrition and safety to non-modified foods, but he noted that food with multiple gene modifications would be more difficult to test and would require further animal studies. A 2004 review of animal feeding trials by Aumaitre and others found no differences among animals eating genetically modified plants.
In 2007, Domingo's search of the PubMed database using 12 search terms indicated that the "number of references" on the safety of GM or transgenic crops was "surprisingly limited", and he questioned whether the safety of GM food had been demonstrated. The review also stated that its conclusions were in agreement with three earlier reviews. However, Vain found 692 research studies in 2007 that focused on GM crop and food safety and found increasing publication rates of such articles in recent years. Vain commented that the multidisciplinarian nature of GM research complicated the retrieval of studies based on it and required many search terms (he used more than 300) and multiple databases. Domingo and Bordonaba reviewed the literature again in 2011 and said that, although there had been a substantial increase in the number of studies since 2006, most were conducted by biotechnology companies "responsible of commercializing these GM plants." In 2016, Domingo published an updated analysis, and concluded that as of that time there were enough independent studies to establish that GM crops were not any more dangerous acutely than conventional foods, while still calling for more long-term studies.
The study by Ricroch, Boisron, and Kuntz (2014) conducted a review of 90-day subchronic feeding studies using foods and feeds derived from genetically modified plants, aiming to assess the ability of these tests to detect adverse effects and their usefulness in the safety assessment process. In all cases considered valid under technical and regulatory criteria, none of the studies identified signs of toxicity, clinically relevant alterations, or unexpected effects attributable to the genetic modification. Nevertheless, the authors note a growing tendency, particularly in the European Union, to systematically require such tests even when existing analyses already demonstrate substantial equivalence, raising concerns about the overinterpretation of minor biological variations and the unnecessary use of animal studies.
Giraldo et al. (2019) conclude that although most genetically modified crops are intended for animal feed, there is a significant lack of information and specific guidelines for the safety assessment of GM forages used exclusively as feed. The study argues that current regulatory frameworks, which were developed primarily for foods intended for human consumption, can be adapted for the assessment of forages, provided that differences in risk profiles and levels of animal exposure are taken into account. The authors further argue that the same methodological approaches used in the assessment of GM foods can be applied to feed, with appropriate technical adjustments, and conclude that adopting a new integrated risk assessment framework would make the process more efficient, reduce unnecessary evaluations, and potentially facilitate the commercialization of GM crops with associated benefits.
Sánchez and Parrott (2017) argue that the 35 studies frequently cited as evidence of adverse effects of genetically modified foods and feeds account for less than 5% of the available literature on GMO safety and exhibit methodological flaws, such as the absence of verification of the actual transgenic content of the diets, lack of appropriate controls, and inadequate feed formulation. They also highlight that some reported negative effects were not specific to the transgene, such as immunogenic responses observed in both GM and non-GM varieties, and that certain studies could not be reproduced. In addition, they identify cases in which studies were presented in a selectively incomplete manner, creating the impression of nonexistent risks, or cited as evidence of harm despite the fact that their own authors did not find adverse effects. In a review published the same year, Panchin and Tuzhikov argue that several studies frequently cited as evidence of harm caused by GMOs exhibit major statistical flaws, particularly due to the failure to properly correct for the problem of multiple comparisons, which leads to false positives that cannot be distinguished from random chance. They further emphasize that many of these studies relied on small sample sizes, conducted numerous tests without predefined hypotheses, and selectively reported results, all of which increase the risk of erroneous conclusions. The authors state that conclusions about the safety of genetically modified crops should be drawn from "the totality of the evidence … instead of far-fetched evidence from single studies."
A study that analyzed the gut microbiota and metabolite profiles in two generations of cynomolgus monkeys fed genetically modified maize found no significant differences in most biological indicators, and the minor variations observed did not affect physiological functions during the feeding period.