More Evidence that Glyphosate May Harm Our Gut Bacteria

Today, more evidence on the detrimental effects of glyphosate on the microbiome, and subsequently, human health.  Researchers at the University of Turku, in Finland, developed a means of predicting whether or not a microbe is sensitive to the chemical.[i] Glyphosate is the active chemical in herbicides like Roundup (the most used herbicicide in the world), and has come under more and more scrutiny in recent years in regards to the question of whether or not it  can harm humans.  I have written about it before on this blog, as it appears that it may exert harmful health effects by damaging the human gut biome.  (See here and here.)  It is already established that it does harm the microbiomes of bees.

According to the non-profit Environmental Working Group, glyphosates have been found in 21 cereal and snack products that it tested, with the highest levels being found in Cheerios and Honey Nut Cheerios Medley Crunch – 6x and 4x the group’s recommended health levels for children.[ii]  In agriculture, glyphosates are mainly used on soy, corn and canola, and in Europe, it is frequently also used on cereals as well as bean and seed crops. It is also used the eradicate weeds prior to sowing.

Glyphosates target an enzyme called EPSPS in a particular metabolic pathway called the shikimate pathway.  This pathway is not found in humans –  only in plants, fungi and bacteria. Because it is not found in humans, the chemical is considered safe.  The enzyme is crucial in the synthesis of 3 essential amino acids, phenylalanine, tyrosine and tryptophan.  Using information about the structure of the enzyme, these scientists were able to classify 80-90% of microbial species based upon whether or not they are sensitive to glyphosates.  Bacteria, such as found in our guts, DO have the pathway.  And thus, research has shifted:  do the chemicals have detrimental effects on human health indirectly, through adversely affecting our old friends?  The news is not good according to this research: it turns out that a conservative estimate has about 54% of the core of the human gut bacteria being sensitive to the chemical (about 20% of the total number of species).

Of the 10 most commonly found bacterial species in humans, 4 are sensitive to the chemical:  3 Bacteroides species and another called, Faecalibacterium prausnitzii. 4 other species are resistant and 2 are unclassified as yet (Roseburia intestinalis and Eubacterium rectale).   The paper includes a long list of other species that are sensitive, many of which should be familiar to my regular readers:  Desulfovibrio, Enterobacter, Prevotella, Bacteroides, Bifidobacterium, Clostridium, , and Ruminococcus, among others.

One more important note:  “The complexity of glyphosate’s effects on the microbiota not only is dependent on the direct impacts of glyphosate blocking or not) the EPSPS enzyme but also has an indirect effect on bacterial interactions.”  So it may affect our biomes both directly and indirectly.  (As I said, not good news.)  Says one of the researchers involved in the study, “This groundbreaking study provides tools for further studies to determine the actual impact of glyphosate on human and animal gut microbiota and thus to their health…”[iii]

Again, it’s important to understand that as yet, there is no definitive proof that glyphosate is harmful to humans.  It’s important to continue to watch the research to see which way the pendulum swings.   As this paper says, “To determine the actual impact of glyphosate on the human gut microbiota and other organisms, further empirical studies are needed…”    So stay tuned!

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[i] Lyydia Leino, Tuomas Tall, Marjo Helander, Irma Saloniemi, Kari Saikkonen, Suvi Ruuskanen, Pere Puigb�. Classification of the glyphosate target enzyme (5-enolpyruvylshikimate-3-phosphate synthase) for assessing sensitivity of organisms to the herbicide. Journal of Hazardous Materials, 2020; 124556 DOI: 10.1016/j.jhazmat.2020.124556

[ii] https://www.usnews.com/news/national-news/articles/what-to-know-about-glyphosate-the-pesticide-in-roundup-weed-killer

[iii] https://www.sciencedaily.com/releases/2020/11/201120095858.htm