Glyphosate Is an Antibiotic. Here Is What That Means for Your Brain.

FEATURE

Glyphosate Is an Antibiotic. Here Is What That Means for Your Brain.

The world’s most widely used herbicide was declared safe for humans on the grounds that it only affects bacteria. Nobody asked what it would do to the bacteria we depend on to stay well.

Glyphosate was patented as an antibiotic before it was patented as a herbicide. The mechanism it uses to kill plants, inhibiting an enzyme called EPSP synthase in a biochemical pathway called the shikimate pathway, is equally effective against bacteria. The shikimate pathway is present in plants, fungi, and bacteria. It is not present in mammals. On the basis of this last fact, regulators declared glyphosate safe for human consumption. Humans do not have the shikimate pathway, therefore glyphosate cannot harm them.

The reasoning had one flaw. The trillions of bacteria living in the human gut have the shikimate pathway. Glyphosate kills them. The safety assessment was conducted as though the human gut microbiome did not exist. At the time, this may have been an honest error. The gut microbiome was not well understood in the 1970s when glyphosate came to market. What has accumulated in the decades since is a research literature documenting what happens when you continuously expose a system you did not account for to a compound specifically designed to kill it.

What you are being exposed to

Approximately 300 million pounds of glyphosate are sprayed on American farms annually. Since the introduction of Roundup Ready crops in the 1990s, engineered to survive direct glyphosate application, use has increased dramatically. Glyphosate is now detectable in drinking water, in rain, in air samples, in the urine of people who work in agriculture and those who do not, in breast milk, and in the bodies of children. You are not choosing to consume it. It is in the baseline of the food supply, the water supply, and the air.

The previous article in this series documented how a single course of prescription antibiotics is associated with a measurably increased risk of depression, because antibiotics disrupt the gut microbiome that produces ninety percent of the body’s serotonin. You are informed of that risk. It is on the label. You make a decision. Glyphosate operates through the same mechanism, on the same ecosystem, at population scale, continuously, without your knowledge, without your consent, and without anything resembling a label.

What the research shows

In 2025, researchers at the University of Puerto Rico School of Medicine published a study in Frontiers in Toxicology exposing rats to glyphosate at doses the EPA considers safe. After ten weeks the animals showed increased anxiety. After sixteen weeks they were freezing in fear at neutral stimuli, things that posed no threat, that healthy animals would have ignored. The researchers found significant reductions in Lactobacillus species in the gut, bacteria central to serotonin production, and increased activity in the brain region directly implicated in anxiety disorders. The animal was not injured. It was not diseased. It had simply been continuously exposed to a compound considered safe, and it had become afraid of things that were not there.

If that description feels familiar, it should. Anxiety, the persistent background sense of threat that does not resolve even in safe circumstances, is among the most common complaints of modern life. The research does not claim glyphosate is the only variable. It claims it is a variable that has been operating silently for decades while the conversation about anxiety has focused almost entirely elsewhere.

A 2022 review in Frontiers in Nutrition, conducted by researchers at the University of British Columbia, found that glyphosate preferentially destroys Ruminococcaceae species in the gut, bacteria whose decline is associated with Parkinson’s disease, schizophrenia, depression, and altered social behavior. The review noted something that deserves more attention than it receives: these effects may be transgenerational. The microbiome disruption caused by a parent’s exposure may be inherited by children who were never directly exposed to the compound at all. The cost does not stop at the body that absorbed it. It moves forward.

A 2024 paper in Ecotoxicology and Environmental Safety documented glyphosate’s impact across the microbiota-gut-brain axis and immune-nervous system, identifying pathways of multiorgan toxicity. The International Agency for Research on Cancer classified glyphosate as probably carcinogenic to humans in 2015. Bayer, which acquired Monsanto in 2018, has paid out more than ten billion dollars in cancer settlements in the United States. The product is still in the food supply. The company still maintains it is safe.

The regulatory window that opened and closed

In May 2025, the Make America Healthy Again Commission released a report that, for the first time in the history of the federal government, explicitly named glyphosate as a compound damaging to the health of Americans. It documented reproductive and developmental disorders, cancers, liver inflammation, and metabolic disturbances. It called for the regulatory framework to be continually evaluated. For a moment, it appeared that the question was finally being asked at the level where it could be answered.

Four months later, a senior EPA official confirmed publicly that the second MAHA report would defer to existing regulatory frameworks. The frameworks that had found glyphosate safe. The window opened in May. It closed by September. The acknowledgement of the problem and the decision not to address it occupied the same calendar year. This is not unusual. It is the pattern.

The original safety assessment of glyphosate assumed the human body had no shikimate pathway and therefore could not be harmed. The assumption was technically correct and practically catastrophic. The bacteria that sustain mood, that produce serotonin and regulate the vagus nerve and govern inflammatory signaling throughout the body, have the shikimate pathway. They have been continuously exposed to a compound designed to kill organisms with the shikimate pathway for fifty years. The cost of that exposure does not appear on any corporate balance sheet. It appears as rising rates of depression, anxiety, and neurological illness in populations eating the food, drinking the water, and breathing the air. It appears in the children of those populations, who inherited the disruption before they were born. And it is diagnosed, managed, and treated with pharmaceutical compounds derived from the same petrochemical supply chain that produces the herbicide causing the harm.

Read the full account of the systems producing this harm and what they cost your body in The Political Gut.