What Does Glyphosate do to the Body?

Written by David Roberts, MPH — Co-Founder, Mara Labs | Johns Hopkins Bloomberg School of Public Health. Published peer-reviewed research on intestinal barrier function and glyphosate-related injury.

How Much Glyphosate Is in People?

Enough that detection is now the ordinary result rather than the exception. A 2024 review in Frontiers in Toxicology reports glyphosate detected in 60% to 80% of the general population, children included. [1]

CDC biomonitoring under the National Health and Nutrition Examination Survey found glyphosate in more than 80% of urine samples drawn from US adults and children. [2]

The compound is also present in blood and breast milk. [1] Whatever else is contested about glyphosate, exposure is not.

This matters for how the rest of the evidence should be read. A substance nearly everyone carries does not need a large individual effect to matter at population scale.

What Does the Strongest Human Evidence Show?

A statistically significant association between heavy glyphosate exposure and non-Hodgkin lymphoma. A 2019 meta-analysis in Mutation Research pooled the updated Agricultural Health Study cohort with five case-control studies. [3]

Among the most heavily exposed groups, relative risk of non-Hodgkin lymphoma was 41% higher than in the least exposed (meta-RR 1.41, 95% CI 1.13–1.75). Sensitivity testing did not shift the estimate. [3]

The authors were not fringe figures. Three of the five had served on the EPA's own scientific advisory panel on glyphosate. [3]

The boundary of that finding is as important as the finding. Those cohorts were licensed pesticide applicators and agricultural workers — people mixing and spraying concentrate, not people eating strawberries.

The study establishes that glyphosate exposure can cause harm at sufficient dose. It does not establish that dietary residue does. Anyone who tells you otherwise has not read past the abstract.

Regulators split on what to conclude. IARC classified glyphosate as a probable human carcinogen in 2015; EFSA found the evidence insufficient in 2022 and approval was renewed for a decade. [1]

Is the Safety Threshold Measuring the Wrong Thing?

Because the regulatory tests study glyphosate alone, and nobody is exposed to glyphosate alone. Commercial herbicides are formulations — glyphosate plus surfactants that help it penetrate plant tissue.

Those surfactants are classified as inert and excluded from long-term toxicity testing. A 2013 study in Toxicology found ethoxylated adjuvants in glyphosate-based herbicides were more cytotoxic to human cells than glyphosate itself. [4]

Acceptable daily intake values are derived from the ingredient. Real exposure is to the mixture. Those are different questions, and only one of them has been asked systematically.

A second gap sits in the exposure estimates themselves. The reassuring figures — chronic dietary intake at a fraction of a percent of the acceptable daily intake — are modeled from food alone. [5] Water, air, dermal contact, and occupational exposure are not in that number.

What Is Nrf2, and Why Does It Govern Everything Downstream?

Nrf2 is the transcription factor that switches on the body's defensive gene network — more than 200 genes covering antioxidant enzymes, detoxification, and inflammatory regulation. [6]

Its resting state is suppression. A protein called Keap1 holds Nrf2 in the cytoplasm and marks it for destruction, so under ordinary conditions it never accumulates. [6]

When a chemical stress modifies specific cysteine residues on Keap1, that grip releases. Nrf2 enters the nucleus and activates the defensive program. [6]

The genes it turns on are the ones that make excretion possible: glutathione S-transferases, NQO1, heme oxygenase-1, glutathione synthetase, and the UDP-glucuronosyltransferases and sulfotransferases of Phase II metabolism. [6] [7]

Dr. John Gildea, Mara Labs' Chief Science Officer, describes it as a general who appears on demand. The troops exist already; nothing moves until the order is given.

Animal work shows what happens without it. Nrf2-deficient mice are markedly more susceptible to chemically induced liver and lung injury than normal animals. [8]

Which raises the question this article exists to ask. What if a compound most people carry every day interferes with the switch itself?

What Happened When We Put Glyphosate on Human Liver Cells?

Nrf2 levels fell by roughly a third. Dr. Gildea ran the experiment in HepG2 cells, a human liver line used as a standard model for how the body processes toxins, comparing glyphosate against a vehicle control.

Heme oxygenase-1, a gene switched on by Nrf2, dropped in parallel. That second result is what gives the first one weight — the effect reached the downstream output, not just the transcription factor.

Gildea's explanation for why this had not been reported before is a methodological one. Standard assays cannot resolve baseline Nrf2 at all.

If you cannot see the resting level, you cannot measure a decrease from it. Most published work was not equipped to detect this even if it had looked.

A third condition added stabilized sulforaphane at 2 µM, a concentration achievable in human blood. Nrf2 more than doubled against baseline.

With glyphosate and sulforaphane together, Nrf2 remained above the untreated control — the suppression was bypassed rather than merely offset.

A separate Mara Labs study, documented in a 2023 white paper, measured glutathione induction in the same cell line across several sulforaphane products and found the stabilized form produced the largest response. [10]

Why Would Suppressing Nrf2 Amplify Every Other Exposure?

Because Nrf2 is not one defense among many. It is the control point for the system that clears most of what you encounter.

Suppress it, and the deficit is not limited to glyphosate. Every compound that depends on Phase II conjugation for excretion—combustion byproducts, industrial solvents, other agricultural chemicals—clears more slowly.

Dr. Martin Katz, a co-founder and board-certified physician, uses a kitchen-sink image borrowed from Dean Ornish. The taps are running and the drain is blocked.

Most environmental health discussion concerns what is coming out of the taps. This mechanism concerns the drain.

Gildea puts the implication in one line: "That would be my prescription for disease. Lower Nrf2."

It would also explain something otherwise puzzling about glyphosate — the sheer breadth of conditions it has been associated with, across organ systems with little in common.

A compound that degraded general clearance capacity would produce exactly that pattern: diffuse associations, no single signature injury, and effects that vary with whatever else a person is carrying.

Stated carefully, this remains a hypothesis. It is consistent with the cell data and with the epidemiology, and it has not been demonstrated in humans.

Where Does Glyphosate Concentrate in the Food Supply?

In grains and legumes, not in the produce aisle where most consumer attention lands. The reason is a practice called pre-harvest desiccation.

Rather than waiting for a crop to dry naturally, growers spray glyphosate shortly before harvest to kill it and even out moisture. The application happens days from processing, with no growing season left for degradation.

Wheat, oats, barley, lentils, chickpeas, and dry beans are the crops where this is routine. [11]

Independent testing using mass spectrometry at accredited laboratories has found residue across breads, oats, pulses, and grain-based products from major US retailers. [11]

It also explains a result that confuses shoppers. Of 26 non-GMO-labeled products tested in one 2022 program, 18 contained glyphosate. [11]

Non-GMO certification addresses genetic modification. It does not address a herbicide sprayed on a conventional crop as a drying agent.

What Reduces Exposure, and What Doesn't?

Choosing organic for desiccated crops does more than any other single change, because that is where residue concentrates. Organic certification prohibits glyphosate use.

If the budget is limited, spend it on oats, wheat products, lentils, and chickpeas rather than on fresh fruits and vegetables.

Washing has limits worth knowing. It removes surface residue, soil, and bacteria, but glyphosate applied pre-harvest is absorbed into plant tissue rather than sitting on the skin.

Water is worth checking. Municipal supplies are permitted glyphosate at concentrations well above European limits, and testing your own supply tells you more than a general assumption either way.

Reducing exposure is the first move, and Katz is direct that it is the one that matters most: eliminating the source comes before anything else. His view on the compound is unambiguous — "I don't think we can get rid of glyphosate fast enough."

On the other side of the equation, Phase II capacity is not fixed. In a placebo-controlled trial of 291 participants, a sulforaphane-containing broccoli sprout beverage raised urinary excretion of benzene conjugates by 61% and acrolein conjugates by 23%, sustained across twelve weeks. [12]

Those trials measured combustion and air-pollution compounds, not glyphosate. No published human trial has tested whether sulforaphane affects glyphosate clearance, and that gap should be stated rather than glossed.

Cruciferous vegetables — broccoli, cabbage, kale, Brussels sprouts, radish — are the dietary route to the same pathway. Enzymes induced through it remain active for days rather than hours. [13]

What Is Still Unresolved?

Most of the specifics are the honest position and also the uncomfortable one.

The lymphoma association is drawn from occupational cohorts. Whether dietary residue carries comparable risk has not been demonstrated, and the exposure difference between spraying concentrate and eating bread is large.

The Nrf2 suppression finding is cell-culture work awaiting peer review and replication. A result in HepG2 cells is a reason to run the human study, not a substitute for having run it.

The adjuvant question is a genuine hole in the regulatory framework rather than evidence of harm. It means the reassurance is narrower than it sounds, not that the reassurance is wrong.

What can be said without hedging: exposure is near-universal, the safety framework tests a narrower thing than people are exposed to, and residue concentrates somewhere other than where public attention has been directed.

That is enough to justify reducing exposure where it is straightforward. It is not enough to justify certainty in either direction, and anyone selling you certainty here — in either direction — is selling something.

Frequently Asked Questions

This article is for educational purposes and is not medical advice. Consult a healthcare professional about your own exposure, symptoms, or treatment, and before beginning any new supplement — especially if you are pregnant, nursing, taking medication, or managing a health condition.