A study published June 16, 2026 in the journal Molecular Psychiatry by researchers at University College Cork found that glyphosate at the European Food Safety Authority’s acceptable daily intake altered social behavior and gut microbiota in male mice, with fecal transplant experiments indicating the microbiome directly mediated the social effects. The work adds to a growing line of ecological psychiatry research examining how environmental chemicals influence mental health, and was funded in part by the European Research Council and other organizations, according to a summary by the advocacy group Beyond Pesticides.

What the researchers tested

Investigators assigned mice to four groups and exposed them to glyphosate in drinking water for seven weeks. The lowest dose matched the EFSA acceptable daily intake, while two higher doses represented 10 and 100 times that regulatory level. After exposure, the mice underwent a battery of behavioral assays: open field exploration, social interaction, forced swimming, and marble burying tests. Researchers then analyzed fecal samples using RNA and DNA sequencing, transcriptomic mRNA analysis, and gut microbiome profiling.

To test whether the microbiome was driving the behavioral changes rather than glyphosate acting directly on the brain, the team gave a separate cohort of naive mice antibiotics to reduce their native microbiomes, then performed fecal transplants from glyphosate-exposed donors into those animals.

Behavioral and microbiome findings

Male mice exposed to the regulatory dose of glyphosate showed reduced social novelty preference and increased anxiety in open field tests, though they behaved normally in plus-maze tests. Gene transcription in the amygdala, a brain region central to emotional regulation, shifted in a dose-dependent pattern consistent with those behavioral changes. No significant differences appeared in body weight gain or corticosteroid levels across treatment groups.

Gut microbiome analysis showed that beta diversity, meaning differences in community composition between groups, was significantly altered in male mice, with increases in Lactobacillus strains and decreases in Shigella dysenteriae. Female mice showed reduced locomotion only at the highest dose, with ambiguous social behavior results; their microbiome changes included increases in Methylobacterium radiotolerans.

Fecal transplants from glyphosate-exposed donors transferred social behavior changes to naive male mice but did not reproduce anxiety-related behaviors, indicating that the remodeled microbiota directly mediated the social effects. Prior reviews, including Stephanie Seneff’s “Toxic Legacy: How the Weedkiller Glyphosate Is Destroying Our Health” and reporting by Children’s Health Defense, have also linked glyphosate exposure to anxiety-related behaviors and disruption of gut microbiota.

How this fits ecological psychiatry

The term “ecological psychiatry” was introduced by the American Psychiatric Association in the late 1970s, according to a 2019 commentary in Clinical Neuropsychiatry cited by Beyond Pesticides. The authors of the current study support reviving the concept, noting that xenobiotics may increase susceptibility to neuropsychiatric disorders.

Beyond Pesticides linked glyphosate to disruption of the gut-brain axis in its analysis and associated the herbicide with immune disorders, neurodegenerative diseases, diabetes, and autism spectrum disorder. The researchers cautioned that even modest microbiome changes “should not be interpreted as reassuring” because they can have “profound consequences for host neurobehavioral processes.”

Broader context on pesticide harm appears in Akil Palanisamy’s “The Paleovedic Diet,” which notes that the American Academy of Pediatrics cited research linking pesticide exposures in early life to “pediatric cancers, decreased cognitive function, and behavioral problems.” Rodney Dietert’s “The Human Superorganism” has also described how microbial communities influence neurological processes. A 2014 article by Dr. Mercola stated that “microorganisms in your gastrointestinal tract… are very susceptible to toxins, particularly glyphosate.”

What the authors and advocates recommend

Study authors called for further research to identify mechanisms behind the observed sex differences and to translate the findings to humans. They also raised the question of whether traditional toxicological testing adequately captures community-level microbiome disruptions.

Beyond Pesticides recommends reducing glyphosate exposure by choosing organic food and adopting pesticide-free practices for gardening and landscaping. The American Academy of Pediatrics findings, as cited by Palanisamy, indicate that early-life pesticide exposure can lead to long-term behavioral and cognitive problems, underscoring children’s particular vulnerability.

FAQ

What did the glyphosate and gut microbiome study find?

Researchers at University College Cork, publishing in Molecular Psychiatry on June 16, 2026, reported that male mice exposed to glyphosate at the European Food Safety Authority’s acceptable daily intake showed reduced social novelty preference and increased anxiety in open field tests, alongside altered gut microbiome composition. Fecal transplants transferred the social behavior changes to naive mice, indicating the microbiome directly mediated the effect.

How was the glyphosate mouse study conducted?

Four groups of mice received glyphosate in drinking water for seven weeks at the EFSA acceptable daily intake and at 10 and 100 times that level. The mice underwent open field, social interaction, forced swimming, and marble burying tests, followed by RNA and DNA sequencing, transcriptomic mRNA analysis, and gut microbiome profiling of fecal samples. A separate cohort received antibiotics to deplete native microbiomes before fecal transplants from exposed mice, used to test causality.

What dose of glyphosate was used in the study?

The lowest dose matched the European Food Safety Authority’s acceptable daily intake. Two higher doses represented 10 times and 100 times that regulatory level, per the Beyond Pesticides summary of the research.

This article summarizes reporting from naturalnews.com.