Glyphosate side effects start in the gut. The weed killer blocks an enzyme human cells never had. But 54% of the species in the core human gut microbiome carry it. Rats drank it at the European daily allowance. The blocked enzyme’s products piled up in the cecum (the start of the colon). They never showed in the blood.
She is fifty-one. She eats vegetables at every meal, whole grains, beans, almost nothing out of a packet. She has had three years of bloating and loose stools nobody has explained. Did you search glyphosate side effects after reading a label like hers? The answer starts where she was not looking: on the produce, not in the packet.
The chapter video, The Antibiotic on Your Salad, makes the case in under ten minutes. What follows is what a pain practice needs from it, because a first brain under selective pressure (steady attack) does not keep the trouble inside the belly.
The intake form counts antibiotic courses. I ask everyone how many rounds of amoxicillin they have swallowed. For most of my career I never asked what had been sprayed on their salad.
The enzyme you do not own, and your bacteria do
Glyphosate does one thing. It blocks 5-enolpyruvylshikimate-3-phosphate synthase. Plants and microbes use that enzyme to build phenylalanine, tyrosine and tryptophan through the shikimate pathway. Human cells never had that pathway. That is the whole safety argument, and for the human cell it is true. You cannot jam a lock you do not have.
Then finish the sentence. Researchers sorted thousands of species into sensitive and resistant types by the shape of the enzyme. Of the species in the core human gut microbiome, 54% land in the sensitive column. The authors called that a low guess. Your cells do not carry the target. Half your friendly gut bacteria do. Only the first half of that sentence was ever tested. The compounds engineered into packaged food were at least tested in something alive. This one was built to kill bacteria. Then it was sprayed across the food supply for fifty years. It was never tested against a human gut community.
The pushback is fair and it belongs here. A second group checked whether the genes were switched on, not just present. They looked at 734 paired metagenomes and 2,144 human fecal metagenomes. They found most gut bacteria lack a full shikimate pathway. Where it exists, it is mostly switched off. Most bacteria grab ready-made amino acids instead. So two computer surveys gave opposite answers. Neither one measured a living gut. That is the level of proof, which is why the tiebreaker has to be an animal.
The vacancy is the injury, not the kill
The lab-dish work behind the popular story had the damage running the worst way. In broth, Salmonella Enteritidis, Salmonella Typhimurium and Clostridium perfringens held up well, while Enterococcus faecalis, Enterococcus faecium, Bifidobacterium adolescentis and the Lactobacillus species were held back. Those were chicken germs in a dish in 2013, before the enzyme sorting existed. So the result there shows only what grew in a dish, nothing more. And Campylobacter was held back too.
The direction still matters, because it is the reverse of what you want from anything in food. The authors read the loss of Enterococcus as what lets clostridia spread. Picture a pressure that clears out the germs holding a spot and spares the ones waiting to take it. It does not sterilize a gut. It re-staffs the community. Whoever ends up holding the spot is what you live with for years.
Glyphosate side effects: measured in the gut, invisible in the blood
Two rodent studies used doses a regulator signed off on. Mice got about the American acceptable daily intake of 1.75 mg/kg. Their gut bacteria shifted. They had more inflammatory CD4 IL-17A T cells. They had more lipocalin-2, a marker of gut inflammation. That is a mouse. And the word low-dose in its title needs a footnote the title never gives. The dose is about a hundred times what people really take in.
Rats drank it for ninety days at the European daily allowance and at two higher no-effect levels. Shikimic acid and 3-dehydroshikimic acid piled up in the cecum, the pouch where the colon begins. That is the fingerprint of the target enzyme being blocked inside a living mammal at a legal dose. Those changes in the cecum did not show up in the blood. One detail cuts against the tidy version. Shikimic acid itself could not be measured in blood, because proteins got in the way of the test. So part of that silence is the test, not the animal.
Safety testing looks in blood. The thing you can measure happens further down, in the cecum. The ninety-day dog study behind the European limit was built to watch a dog. Back then, nobody thought its gut bacteria were worth counting. Follow the money, not a villain. A cheap chemical that works gets used everywhere. No budget line pays anyone to sample a cecum. That is a bookkeeping choice, not a conspiracy.
The window where a pain patient is most exposed
Here is the part the surveys cannot settle, and the part that matters in the clinic. Gene activity in a settled adult gut shows what the pathway does today, in people who are not sick. It says nothing about a gut rebuilding after antibiotics, after belly surgery, after a hospital stay. Those are the moments when bacteria must build their own amino acids instead of grabbing them. Quiet at rest is not quiet under load. My patients live in that window.
Exposure itself is not in question. A national American sample tested 2,310 urine specimens. Glyphosate showed up in 81.2% of people aged six and older. The middle level was 0.392 micrograms per liter. People who had fasted more than eight hours had significantly lower levels. Fast and the number falls. That is how you know it came in with lunch.
The study that would settle this in a person has never been run. That is not because the answer came back negative. Its entry rules would shut out anyone with an upset bowel, a metabolic disease, a psychiatric diagnosis or a long drug list. That describes the very patient with the symptoms. So we use the measured mechanism instead and say the level of proof out loud. We do the same when an exposure jams energy production before any panel flags it.
The thing sprayed is not the thing tested
No tank holds the pure molecule. What gets sprayed is a product. Its soap-like additives help it soak into a leaf. Polyethoxylated amine surfactants, the first generation of those additives, were far more toxic than glyphosate itself. From the mid-1990s they gave way to additives about a hundred times less toxic to human cells and water life. Regulators assume these added ingredients are harmless. They mostly leave them out of safety checks.
Against human cells, the sprayed products were more toxic than their active ingredients alone. In bacteria in a dish, the store product stopped growth at levels where the active ingredient alone did not. So the safe daily limit is set on one molecule, but the exposure is to a mixture. That is worse than it sounds. If the product hits bacteria harder than the pure chemical, every promise built on the pure chemical measured the wrong thing at the right dose. And that looks like an answer. It is why we work the measurable driver first. We treat the one we cannot measure as a reason to change a habit, not buy a test.
What we do with an exposure nobody can measure
I did not tell her that glyphosate is wrecking her gut bacteria. In people, the measuring stops at urine. There is no number for her gut, no normal range, and nothing worth ordering.
I told her something narrower and more useful. Four out of five Americans carry a chemical from her food. All it does is block an enzyme her bacteria have and her cells do not. At a legal dose, that enzyme is clearly blocked in the gut of a mammal. And the proof never reaches the blood, the place safety testing looks.
Then we did the two things we could. Her produce gets washed, or bought organic where residue data say it matters. That is cheap, and no one has measured the benefit. I said so out loud. The body science under it is the fasting result. Exposure arrives with meals and clears fast. So the lever is where your raw food comes from, not a cleanse. The rest of the visit went to exposures I can measure and change, because three years of symptoms deserve the treatments with proof behind them before the ones without. None of this is a reason to start or stop a medication. That is a talk for you and the physician who holds your whole history.
The cost of doing nothing is not dramatic. It is another fifty years of the same silence, one salad at a time. The Deep Dive for Chapter 22 carries every study and every number behind these paragraphs. It shows what each result proves and what it cannot. Removing an antibiotic you cannot measure is still removing an antibiotic.
Frequently asked questions
Has glyphosate been shown to damage the gut microbiome in people?
No. Nobody has matched a person’s measured exposure with what lives in their gut. So any human result quoted either way is overselling. What exists is a count finding 54% of core gut species carry the target enzyme. There is lab-dish work on chicken germs, insect studies and two rodent studies at accepted doses. A routine blood panel would have called every treated animal fine. Normal test results are often exactly what a mechanism predicts.
Does washing produce actually remove glyphosate?
Washing lowers what sits on the surface. It does nothing about what is inside the plant. So the honest label is a cheap step with an unmeasured benefit. Changing where your raw produce comes from does more, because the exposure arrives with meals. It does not build up for years. Food work is treatment here, not a handout at discharge. See how lifestyle medicine sits inside the plan.
Can pesticide residue explain bloating and loose stools?
It cannot be the answer you settle for, because nothing you can measure in a person ties the two together yet. Chase the causes that have a name, a test and a treatment first. Then cut the exposures you control. Diarrhea that began after belly surgery is the clearest example of a cause with all three. Loose stools after gallbladder surgery have their own diagnosis.
Should I buy a urine glyphosate test?
One urine sample shows yesterday’s meals. It does not show your gut or your risk. No normal range tells you what to do with the result. Spend the money on markers that change the next decision instead. Insulin and inflammation markers qualify, because they move with food, and they move with treatment. Insulin resistance shows up years before a glucose test catches it.
Bring the exposures you can change
Have years of bloating, urgency or unexplained pain outlasted every normal test? The useful next step is a look at the terrain feeding them. Bring your medication history, your surgery history and a week of your own food labels.
Request an appointment, or call or text us.
Sources
- Ferguson, S., Mesnage, R., & Antoniou, M. N. (2022). Cytotoxicity mechanisms of eight major herbicide active ingredients in comparison to their commercial formulations. Toxics, 10(11), 711. https://doi.org/10.3390/toxics10110711
- Lehman, P. C., Cady, N., Ghimire, S., Shahi, S. K., Shrode, R. L., Lehmler, H.-J., & Mangalam, A. K. (2023). Low-dose glyphosate exposure alters gut microbiota composition and modulates gut homeostasis. Environmental Toxicology and Pharmacology, 100, 104149. https://doi.org/10.1016/j.etap.2023.104149
- Leino, L., Tall, T., Helander, M., Saloniemi, I., Saikkonen, K., Ruuskanen, S., & Puigbò, P. (2021). Classification of the glyphosate target enzyme (5-enolpyruvylshikimate-3-phosphate synthase) for assessing sensitivity of organisms to the herbicide. Journal of Hazardous Materials, 408, 124556. https://doi.org/10.1016/j.jhazmat.2020.124556
- Mesnage, R., & Antoniou, M. N. (2020). Computational modelling provides insight into the effects of glyphosate on the shikimate pathway in the human gut microbiome. Current Research in Toxicology, 1, 25-33. https://doi.org/10.1016/j.crtox.2020.04.001
- Mesnage, R., Benbrook, C., & Antoniou, M. N. (2019). Insight into the confusion over surfactant co-formulants in glyphosate-based herbicides. Food and Chemical Toxicology, 128, 137-145. https://doi.org/10.1016/j.fct.2019.03.053
- Mesnage, R., Teixeira, M., Mandrioli, D., Falcioni, L., Ducarmon, Q. R., Zwittink, R. D., Mazzacuva, F., Caldwell, A., Halket, J., Amiel, C., Panoff, J.-M., Belpoggi, F., & Antoniou, M. N. (2021). Use of shotgun metagenomics and metabolomics to evaluate the impact of glyphosate or Roundup MON 52276 on the gut microbiota and serum metabolome of Sprague-Dawley rats. Environmental Health Perspectives, 129(1), 17005. https://doi.org/10.1289/EHP6990
- Ospina, M., Schütze, A., Morales-Agudelo, P., Vidal, M., Wong, L.-Y., & Calafat, A. M. (2022). Exposure to glyphosate in the United States: Data from the 2013-2014 National Health and Nutrition Examination Survey. Environment International, 170, 107620. https://doi.org/10.1016/j.envint.2022.107620
- Shehata, A. A., Schrödl, W., Aldin, A. A., Hafez, H. M., & Krüger, M. (2013). The effect of glyphosate on potential pathogens and beneficial members of poultry microbiota in vitro. Current Microbiology, 66(4), 350-358. https://doi.org/10.1007/s00284-012-0277-2
Dr. Gurpreet Singh Padda, MD, MBA, MHP
