What Are The Health Risks Associated with Genetically Modified Foods?

Mounting evidence implicates glyphosate, marketed as Roundup®, – with most of the diseases and conditions blamed on the Western diet: gastrointestinal disorders, obesity, diabetes, heart disease, depression, autism, infertility, cancer and Alzheimer’s disease.

Quail managers take note: glyphosate has been shown to have remarkable adverse effects on the gut biota in poultry. It drastically reduces the number of beneficial bacteria and increases the number of pathogenic bacteria in the gut.

This is a clue to quail diseases and parasites. Quail are disappearing across their ranges especially in proximity to farming areas and even in areas where heavy feeding occurs.  Glyphosate is part of most farming operations, and most feed grains now have glyphosate residues.

Summary of Paper

That genetically modified foods pose a risk is now evident in a large review article published at Entropy 2013 (online science journal, publicly available): Glyphosate’s Suppression of Cytochrome P450 Enzymes and Amino Acid Biosynthesis by the Gut Microbiome: Pathways to Modern Diseases, by Anthony Samsel and Stephanie Seneff

It contains an exhaustive (and exhausting) survey of 286 studies reporting correlations between glyphosate, the chemical agent in RoundUp, and almost every human malady. While not every study may support a significant connection, the sheer mass of studies should make us cautious.

Bottom line for personal health: Avoid GM foods, because these are the very foods made to be resistant to glyphosate, and treated at harvest to have a large content of it as they reach market.

Hoped for action by legislators: Enact legislation for the accurate labeling of processed foods containing GM food, and for identification in supermarket produce sections as to which vegetables are genetically modified (GM).


• Glyphosate was originally discovered by Monsanto as a good inhibitor of EPSP synthase in the pathway for the synthesis of aromatic amino acids. It was considered non-toxic in animals because we do not have this enzyme. We do not synthesize aromatic amino acids, we get these amino acids in our diet.

• Short term studies with mice showed no harmful effects, and use of RoundUp was deemed safe.

• More recently glyphoosate has been observed to inhibit CYP’s, such as CytP450 reductase etc. CYP is jargon for cytochrome proteins, which are enzymes that use cytochrome as a cofactor in various chemical reactions.

• 100,000 tons of glyphosate or RoundUp are applied per year in the US, and it is now detectable in fresh water streams in the Midwest.

Perhaps half of the crops grown by agribusiness are GM types made glyphosate resistant. Therefore, it has become a somewhat common practice to spray a day or two before harvesting crops, to kill off any weeds that may have grown there, so that they don’t interfere with harvesting. This then increases glyphosate content in produce just before it is shipped to market.

• Plants have been shown to incorporate glyphosate linearly for more than 8 hours, so such last sprayings would load with glyphosate all the plants to be harvested. While the crops are now resistant (Monsanto GM varieties), humans who eat them are not yet so modified.

• Many of the health problems that appear to be associated with a Western diet could be explained by biological disruptions that have already been attributed to glyphosate. These include digestive issues, obesity, autism, Alzheimer’s disease, depression, Parkinson’s disease, liver diseases, and cancer.

• Because it also kills gut bacteria, the ‘symbiotic’ benefits of such bacteria on the digestive tract itself, as well as immune function etc. may be compromised or influenced.

• Glyphosate has been shown to have remarkable adverse effects on the gut biota in poultry, by reducing the number of beneficial bacteria and increasing the number of pathogenic bacteria in the gut. Highly pathogenic strains of Salmonella and Clostridium were found to be highly resistant to glyphosate, whereas beneficial bacteria such as Enterococcus, Bacillus and Lactobacillus were found to be especially susceptible.

• In a case-control study, children with autism were found to be significantly more likely to have been formula-fed rather than breast-fed. The study did not distinguish between organic and non-organic formula, but one can surmise that non-organic soy formula might be contaminated with glyphosate.

• Urinary bacterial metabolites of phenylalanine, such as benzoic and phenylacetic acids, and of tyrosine (p-hydroxybenzoic acid and p-hydroxyphenylacetic acid) have been found to be elevated in association with several different diseases reflecting impaired intestinal resorption, including coeliac disease, cystic fibrosis, and unclassified diarrhoea.

• Autism is associated with dysbiosis in the gut, along with impaired sulfate metabolism and a significantly reduced level of free sulfate in the blood stream (only one-third of the normal level), excess production of nitric oxide, overgrowth of phenol-producing bacteria like C. difficile and increased urinary levels of the toxic phenol, p-cresol. Autism is also associated with a decreased ability to use sulfate and hence detoxify acetaminophen, which aligns with insufficient sulfate bioavailability.

• Colitis and Crohn’s disease are associated with sulfate depletion in the gut.

As little as 10 ppm of glyphosate disrupted aromatase activity in human liver HepG2 cells, a well-established cell line to study xenobiotic toxicity. i.e. having glyphosate in our liver would decrease liver ability to detoxify any other compounds.

• Cytochrome P450 reductase: was assayed for activity level in hydrolyzing benzo(a)pyrene, in the presence of glyphosate. At 15 µM glyphosate, enzyme activity was reduced by a factor of four; by 35 µM enzyme activity was completely eliminated.

Cytochrome P450 Enzymes

• There are at least 18 distinct CYP families in humans,

• CYP1, CYP2, CYP3, and CYP4 P450 enzymes in the liver are essential for detoxification of many xenobiotics (mentioned above).

• CYP5 and CYP7 classes are essential for the formation of water-soluble bile acids from cholesterol in the liver.

• Two CYP enzymes in the liver catalyze 25-hydroxylation of vitamin D3 to its active form.

• Endothelial nitric oxide synthase (eNOS) is a CYP enzyme; present in endothelial cells that synthesize nitric oxide (NO), which induces vessel relaxation and therefore enhanced blood flow. i.e. blood pressure is influenced.

Involvement of the Brain:

Serotonin, Mood Disorders, and Autism

Ammonia, Autism and Alzheimer’s Disease

Role for Zinc Deficiency

Methylation Impairment: results in altering epigenetic programming in animals!

Due to a lack of the amino acid methionine, much of which normally comes from our gut bacteria.

• Dietary reductions of phenylalanine and tyrosine induce reduced dopamine concentrations in the brain. Impaired dopaminergic signaling in the substantia nigra is a key feature of Parkinson’s disease, and Parkinson’s risk has been associated with
exposure to various pesticides.

Missing Data:

1. Actual values for concentrations of glyphosate found in human fluids or cells (it may be tough to get such numbers).

2. The lifetime or stability for glyphosate in body fluids, cells, etc, before it is chemically altered to be less toxic. Presumably it is stable in the manufactured form; there are some limited data on conversion by bacteria in the gut, but it is not clear how long glyphosate lasts in soil as it leaches towards a stream or aquifer.


Since this paper was published, the World Health Organization (WHO) and the State of California have determined that glyphosate is probably carcinogenic.


Posted by Chris Gill

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