Human exposure to genetically modified microorganisms via drugs, food additives and new GMOs poses serious risks to public health. A scientific review (Lerner et al., 2024) published in Microorganisms offers a stimulus to reform food and drug safety rules. (1)
1) Threatened intestinal microbiota
Intestinal dysbiosis – that is, the imbalance in the composition and function of the microbiome (the community of beneficial microorganisms also known as the ‘bacterial flora’) – is associated with the Western lifestyle (ultraprocessed foods, first and foremost) as well as various inflammatory, neurodegenerative, neurodevelopmental, infectious, metabolic, tumor and autoimmune diseases (AD).
A possible cause of microbiome imbalance is indicated by researchers in the introduction of genetically modified microorganisms into the human intestine. The advance of harmful genes is made possible by horizontal gene transfer, the main mechanism of bacterial evolution. The researchers point to some examples.
2) Resistance to antibiotics and drugs
The mechanism of horizontal gene transfer allows the entry of microorganisms resistant to antibiotics, antimicrobials, phages (viruses that are parasites of bacteria) and tumor drugs.
Resistance genes multidrug products are also conveyed through contaminated and industrially processed nutrients. The carriers are different. The authors of the study recall evidence on Lactobacillus reuteri, antibiotics and antibiotic residues in foods of animal origin.
‘The emergence of the resistome represents a global health threat driven by the growing unnecessary use of antibiotics and cancer therapies’, say the researchers, who question whether genetically modified microorganisms are screened for genes resistant to antibiotics and other drugs.
3) Genetically modified microorganisms in foods and probiotics
Genetically modified microorganisms are widely employed, without the knowledge of consumers.
The food industry uses them to produce vitamins, flavors, enzymes and preservatives. The authors of the study dedicate an in-depth study to microbial transglutaminase, a problematic enzyme present in many industrial foods, but not declared on the label because it is classified as a technological adjuvant.
3.1) Microbial transglutaminase
Microbial transglutaminase is a genetically modified enzyme with potential pro-inflammatory, immunogenic, allergenic, pathogenic and potentially toxic effects. It has recently been indicated as a potential inducer of celiac disease. (2)
It is employed as a glue for assembling surimi, frankfurters, yogurt, tofu and in gluten-free baked goods.
3.2) Probiotics and antibiotic resistance
Probiotics, generally considered useful and safe, instead pose risks of significant side effects, such as antibiotic resistance.
In the engineered version, i.e. genetically modified, show clinical benefits for inflammatory intestinal, infectious, tumor and metabolic diseases. (3) However, the authors of the study point out, they could influence the composition of the intestinal microbiota, which is known to be crucial for human health.
3.3) Genetically modified plants
Genetically modified plants are proposed as a solution to increase agricultural production thanks to resistance to drought, crop parasites and diseases, and high doses of pesticides (glyphosate, primarily).
However, there are risks for humans, animals and the environment, warn researchers, according to whom genetically modified plants ‘they can invade the human microbiome or genome‘.
3.4) Pharmacological treatments
Insulin, hormones growth and vaccines are also produced (more economically) with genetically modified microorganisms.
In medicine, furthermore, they spreadrecently developed techniques of bacterial-mediated drug delivery using genetically modified microbes with the aim of locally delivering recombinant therapeutic proteins to the human intestine. They are often called live biotherapeutic products, but they deliberately carry potential risks‘, according to the researchers.
4) Unbalanced homeostasis and diseases
Genetically modified microorganisms are potentially involved in chronic human diseases characterized by imbalanced intestinal homeostasis. That means:
– autoimmune diseases, such as type 1 diabetes, multiple sclerosis, celiac disease and psoriasis,
– neurodegenerative conditions. It is assumed that genetically modified microorganisms can potentially promote neuroinflammatory/degenerative diseases, related to dysbiosis, as we have seen, (4)
– metabolic diseases. All components of metabolic syndrome are related to a disrupted gut microbiome,
– allergies. Food allergy is highly related to intestinal dysbiosis,
– cancer induction or therapy. Horizontal gene transferoccurs between prokaryotes and eukaryotes, and microbes, viruses, or fungi are related to the induction of human cancer. A recent example is the involvement of engineered E. coli Nissle 1917 in colorectal cancer. In contrast, prokaryotes are increasingly reported as key players in cancer immunotherapy, applying engineered biotechnologies to combat the spread of metastasis.
Since prevention is the most cost-effective way to fight cancer or other human chronic diseases, strictly regulate and control GEMs (genetically modified microorganisms, ed.) and avoiding the entry of MGE (mobile genetic elements, ed.) into the human microbiome or genome represent the most rewarding means of protecting people from such morbid and deadly conditions’,
– neurodevelopment and behavior. The intestinal microbiota represents a potential biomarker of the risk of mental and behavioral morbidities. Fundamentally, the gut’s eubiotic diversity and synergistic composition influence brain function, thus playing a critical role in emotional processing.
Various neuropsychiatric conditions are dysbiotic-dependent:
- Alzheimer’s disease,
- attention deficit hyperactivity disorder,
- amyotrophic lateral sclerosis,
- nervous anorexia,
- bipolar disorder,
- generalized anxiety disorder,
- major depressive disorder,
- multiple sclerosis and schizophrenia,
– female and male infertility. Gut microbes also have potential causal effects on the fertility of females and males.
5) Prima non nocere
The authors of the study encourage regulatory authorities around the world to adopt a more holistic and aligned approach to the risk assessment and regulatory oversight of food ingredients, immune factors, enzymes and any category of food substances produced with GEMs (genetically engineered microorganisms) that can allow safe and sustainable food choices and consumption by consumers.
‘It is important to remember that prevention is the most cost-effective strategy and that primum non nocere should be the focus‘.
Marta Strinati
Footnotes
(1) Lerner A, Benzvi C, Vojdani A. The Potential Harmful Effects of Genetically Engineered Microorganisms (GEMs) on the Intestinal Microbiome and Public Health. Microorganisms. 2024; 12(2):238. https://doi.org/10.3390/microorganisms12020238
(2) Lerner, A.; Matthias, T. Microbial transglutaminase should be considered as an environmental inducer of celiac disease. World J. Clin. Cases 2019, 7, 3912–3914 DOI: 10.12998/wjcc.v7.i22.3912
(3) Ma, J., Lyu, Y., Liu, X. et al. Engineered probiotics. Microb Cell Fact 21, 72 (2022). https://doi.org/10.1186/s12934-022-01799-0
(4) Marta Strinati, Dario Dongo. Direct causal relationship between intestinal microbiota and Alzheimer’s, the study. GIFT (Great Italian Food Trade). 4.1.24.
Professional journalist since January 1995, he has worked for newspapers (Il Messaggero, Paese Sera, La Stampa) and periodicals (NumeroUno, Il Salvagente). She is the author of journalistic surveys on food, she has published the book "Reading labels to know what we eat".
