A third recent study demonstrates how glyphosate-based herbicides can disrupt the human microbiota, which is the collection of bacteria, viruses, fungi, and other single-celled organisms that live throughout the human body.
Nature.com reports that a new study published in Scientific Reports explored the potential effects of glyphosate-based herbicides on urinary metabolites and their interactions with bacteria in the gut. The study was conducted on rodents. After administering Roundup, the world’s best-selling glypohsate-based weed killer, to rats, researchers identified a significant increase in homocysteine, which is an amino acid. High levels of this amino acid can lead to damage to the arteries and blood clots in the blood vessels.
Complications associated with high homocysteine levels also include Alzheimer’s Disease and dementia; stroke; coronary artery disease; heart attack; and osteoporosis. The researchers concluded, “Our study provides initial evidence that exposures to [glyphosate-based herbicide], at a currently acceptable human exposure dose, is capable of modifying urine metabolites in both rat adults and pups.”
Glyphosate was first produced in 1974 by the Monsanto Corporation, which was acquired by Bayer AG in 2018 for $63 billion. Approximately 9.4 million tons of glyphosate herbicides have been sprayed globally, since Monsanto introduced the active ingredient to the market. This amounts to nearly half a pound of glyphosate having been applied on every cultivated acre of land.
In 1996, Monsanto introduced Roundup-ready crops, which are genetically-modified crops (GMOs), engineered to withstand glyphosate spraying. By mass, two-thirds of the total amount of glyphosate sprayed since Roundup-ready seeds were introduced, has been sprayed in the last 10 years. Glyphosate is also sprayed on non-GMO crops to more quickly dry out the crops in order to speed up the harvesting process.
Over 90% of the corn and soy harvested in the US is grown using GMO seeds. Because of the pervasiveness of glyphosate application to both GMO and non-GMO crops, this further increases the public’s exposure to glyphosate and its major metabolite aminomethylphosphonic acid (AMPA). (Organic foods most often contain less glyphosate residue than their non-organic versions.)
How Does Glyphosate Affect Gut Bacteria?
Glyphosate works to kill unwanted weeds by interfering with a pathway that’s essential for plant growth. This pathway only exists in bacteria, fungi, and plants, but not in vertebrates such as humans. Thus, glyphosate was thought to impose minimal risks to people. However, as the researchers note, “Current emerging evidence suggests that glyphosate or glyphosate-based herbicides [GBHs] such as Roundup, can adversely affect mammalian biology via multiple mechanisms.”
(The researchers also mentioned that “Several studies have also suggested the possible link between GBHs exposure and abnormality in neurodevelopment.”
Previous research shows that glyphosate alters the gut microbiome of rats by inhibiting the so-called “shikimate pathway” that’s necessary for plant growth. In addition, other studies have demonstrated the GBHs alters the microbiota in honeybees, rats and other animals.
The findings should not be considered conclusive as there are limitations to the study, most notably the limited number of rats used in the research.
However, the research echoes a Finnish study published in late 2020 and a study published last month, both of which also found glyphosate to alter the gut microbiome composition.