Over a million New Zealanders may have fatty liver disease — and a growing body of evidence links glyphosate exposure to its rise.
Right now, somewhere between one and one-point-three million New Zealanders are living with a disease they almost certainly don’t know they have.
It doesn’t hurt. It produces no obvious symptoms in its early stages. Most people discover it only by accident — a routine blood test, an ultrasound ordered for something else, an investigation that wasn’t looking for liver disease at all. By the time it does announce itself, significant damage may already have been done.
How do we know so many people are unaware? A major 2025 study published in the Lancet Regional Health Europe examined diagnosis rates across the US, UK, Germany and France and found that fewer than 18% of people with the condition had ever been diagnosed — leaving more than 16.7 million people across just those four countries unaware they had it. There is no reason to think New Zealand’s awareness rates are any better.
The disease is called MASLD — Metabolic dysfunction-associated steatotic liver disease, more commonly known as fatty liver disease. It is the abnormal accumulation of fat in liver cells, progressing in some people through inflammation and scarring (a more serious form called MASH — Metabolic dysfunction-associated steatohepatitis) and in some cases on to liver failure or liver cancer. It is now the most common chronic liver disease in the world, estimated to affect around 38% of adults globally. Without significant intervention, forecasts suggest that figure could exceed 55% by 2040.
New Zealand is not watching this from a distance. We are in it.
Based on international prevalence data applied to New Zealand’s known rates of obesity and diabetes, researchers estimate that somewhere between 25 and 35% of New Zealand adults are already living with MASLD — translating to roughly one to one-point-three million people, the majority unaware.* Among those with obesity — roughly one in three New Zealand adults today — the prevalence climbs toward 70%. Among people with type 2 diabetes, around two-thirds are thought to have the condition. And unlike heart disease or cancer, New Zealand has no national registry for MASLD. We are not counting it systematically. We are not screening for it routinely. Many of those affected will never know until it is serious.
The question worth asking — the question that a growing body of international research is beginning to answer — is why. Why is this disease rising so sharply, and so broadly, across populations that differ in age, weight, diet, and lifestyle? Obesity and poor diet are part of the picture. But researchers are increasingly pointing toward something else. Something most New Zealanders encounter every single day.
Glyphosate: The World’s Most Used Herbicide — and What It’s Doing to the Liver
Glyphosate is the active ingredient in Roundup and dozens of other herbicide products. It is the most widely used weedkiller in the world. Introduced in the 1970s, it became truly ubiquitous with the rise of genetically modified glyphosate-tolerant crops in the 1990s, and today is applied to hundreds of millions of hectares of farmland globally every year.
It is also used in ways that many people don’t expect. As a pre-harvest desiccant, it is sprayed directly onto crops like wheat and oats shortly before harvest to accelerate drying and standardise harvesting schedules. This means glyphosate residues end up in food products — bread, breakfast cereals, oat-based foods — at levels that would not exist if the chemical were used only during the growing phase.
In New Zealand, glyphosate use is pervasive. It is used in horticulture, viticulture, pastoral farming, orchards, roadsides, parks, railway corridors, and home gardens. It is registered, legal, and considered by our regulatory agencies to be safe when used as directed. That assessment, however, is increasingly being challenged — not by activists operating at the fringes of scientific opinion, but by peer-reviewed research published in some of the world’s leading medical and environmental health journals.
What Peer-Reviewed Research Now Links Glyphosate to Liver Disease
A comprehensive analysis published in Environmental Toxicology and Pharmacology in 2025 reviewed 42 separate studies examining glyphosate’s relationship with liver disease. The findings were striking.
People exposed to higher levels of glyphosate and its primary breakdown product — a compound called aminomethylphosphonic acid, or AMPA — showed greater signs of liver dysfunction and higher scores on standardised measures of liver fat accumulation. The strongest associations were seen in women aged 40 to 60 with borderline diabetes. But the effects were not limited to any single demographic group.
Critically, the researchers measured exposure through urine samples — a well-validated way of assessing how much of a chemical a person has actually absorbed into their body. Higher urinary glyphosate correlated with worse liver outcomes even after adjusting for other known risk factors: age, body weight, alcohol consumption. Glyphosate appeared to be doing something to the liver that was independent of the usual suspects.
A separate study published in Clinical Gastroenterology and Hepatology, conducted at UC San Diego, went a step further. Researchers recruited 97 adults who all had confirmed fatty liver disease — verified by liver biopsy, the diagnostic gold standard. They measured glyphosate and AMPA in participants’ urine and mapped those levels against the severity of each person’s condition. The pattern was clear: higher glyphosate exposure corresponded with worse liver scarring, more inflammation, and more advanced disease. And glyphosate’s association with liver damage severity was stronger than that of age, body mass index, or alcohol use — even after statistical adjustment for all of them.
This is not proof of causation. Observational studies have inherent limitations. But the consistency of findings across 42 studies, multiple countries, multiple populations, and multiple methodologies is exactly the kind of signal that warrants serious investigation — and, in the meantime, serious caution.
Early Glyphosate Exposure in Children: The Long-Term Health Risks
Perhaps the most alarming research concerns children, and what early exposure may be setting in motion for their long-term health.
A landmark study known as CHAMACOS — the Center for the Health Assessment of Mothers and Children of Salinas — tracked nearly 500 mother-child pairs from pregnancy through to age 18 in California’s agricultural Salinas Valley. Researchers at UC Berkeley measured glyphosate and AMPA levels in urine at multiple points throughout childhood, then assessed participants’ health as young adults.
The results were sobering. Children with elevated AMPA levels at age 5 — the toddler and early primary school years — faced dramatically worse health outcomes a decade later. For every doubling of AMPA detected at that young age, the odds of developing metabolic syndrome by 18 rose by 55%. Metabolic syndrome is a cluster of conditions — excess abdominal fat, elevated blood pressure, abnormal blood sugar and cholesterol — that substantially increases the lifetime risk of heart disease, type 2 diabetes, and liver disease. The risk of liver inflammation, measured through elevated liver enzymes, climbed by 27% for the same doubling of early AMPA exposure.
The timing mattered enormously. Exposure in early childhood proved far more consequential than exposure during adolescence. The body’s developing systems — hormonal, metabolic, microbial — appear to be particularly vulnerable in those formative years. Disruption at that stage doesn’t simply resolve as a child grows. Evidence suggests it shapes the trajectory of their health across decades.
Geography mattered too. Children living within half a mile of agricultural fields regularly treated with glyphosate-based herbicides had the highest chemical levels in their bodies and the worst health outcomes. Proximity to farming activity was not a background variable — it was one of the strongest predictors in the dataset.
Now consider what that finding might mean in New Zealand. In Hawke’s Bay, in Marlborough, in Nelson, in the Canterbury plains, in the Waikato — children attend schools, play in parks, and grow up in homes within half a mile of intensively farmed land treated regularly with herbicides. We have not measured what is in those children’s bodies. We have not tracked their liver enzymes over time. We have not looked.
Māori and Pacific Peoples: The Communities Most at Risk
New Zealand does not have granular national data on fatty liver disease broken down by ethnicity. But researchers and clinicians are in little doubt about where the disease falls hardest.
One in six adults aged 50 and over with type 2 diabetes has MASH with moderate to advanced fibrosis — a finding from the Lancet paper that underscores just how heavily this disease falls on older people living with metabolic conditions, a group that includes a disproportionate number of Māori and Pacific peoples.
Māori and Pacific peoples experience significantly higher rates of obesity, type 2 diabetes, and metabolic syndrome — all of which are both risk factors for, and consequences of, MASLD. The burden of this disease, therefore, is not evenly distributed. It lands disproportionately on communities that already face compounding health inequities, and that are in many cases also more likely to live and work in close proximity to agricultural land.
This is not a peripheral consideration. It is central to understanding the full scale of what is at stake. Any serious conversation about fatty liver disease in New Zealand has to include an honest reckoning with who is most affected and why — and any response that doesn’t address structural inequity will fail the people who need it most.
How Glyphosate May Damage the Liver: Endocrine Disruption, Oxidative Stress and Gut Microbiome Harm
How does glyphosate produce these effects? Researchers have proposed several biological mechanisms, and they are not mutually exclusive.
The first is endocrine disruption. Glyphosate and commercial glyphosate-containing formulations have been shown in laboratory and animal studies to interfere with hormone-signalling systems. Your endocrine system regulates metabolism, growth, reproduction, and stress response — it is a cornerstone of overall health. Disruption doesn’t produce a single obvious symptom. It subtly shifts the balance of dozens of biological processes simultaneously, with consequences that may only become visible years or decades later. Research published in Women’s Health notes that hormonal disruption from environmental chemicals is particularly significant for women’s metabolic health, helping explain why women aged 40 to 60 appear most affected in the glyphosate-liver studies.
The second is oxidative stress. When glyphosate enters the body, it appears to trigger the production of reactive oxygen species — unstable molecules that damage cells and tissues. In the liver, which is continuously processing everything we eat, drink, and absorb, this kind of oxidative load accumulates. The result is chronic, low-grade inflammation that progressively scars liver tissue and impairs its function.
The third is gut microbiome disruption. Glyphosate is, at its chemical core, an antimicrobial agent. It kills plants by disrupting the shikimate pathway — a biochemical process that bacteria also rely on. Human cells don’t use this pathway, which is why glyphosate was initially considered harmless to people. But the trillions of bacteria that make up the human gut microbiome do. Research increasingly suggests that glyphosate selectively suppresses beneficial gut bacteria while allowing more harmful strains to flourish. Given the gut’s central role in immune regulation, metabolic function, and inflammatory signalling, this disruption has consequences well beyond the digestive tract — including, significantly, in the liver.
New Zealand’s Double Information Gap: No Registry, No Exposure Data
This is where the picture in New Zealand becomes particularly uncomfortable — because we are operating with two overlapping information gaps at once.
The first is that New Zealand has no national registry for fatty liver disease. We do not track MASLD systematically. We do not screen for it routinely in at-risk populations. We do not know, with precision, how many New Zealanders have it, how severely, or how it is progressing over time. The estimates we have — one to one-point-three million people — are informed extrapolations from international prevalence data, not measured figures. Internationally, direct health costs from undiagnosed aggressive fatty liver disease are predicted to triple over the next 20 years. New Zealand is not immune to that trajectory.
The second is that New Zealand has no comprehensive population monitoring of glyphosate exposure. We do not have urinary biomarker data for the general public. We do not have longitudinal data on children in rural horticultural regions. We do not have granular, community-level testing of drinking water and waterways in areas of intensive agricultural use.
What we do have is a regulatory framework that sets acceptable residue limits in food and water based on assessments of glyphosate in isolation. But people are not exposed to glyphosate in isolation. They are exposed to it in combination with the adjuvants and co-formulants in commercial herbicide products, alongside other agricultural chemicals, and continuously across years and decades — not in the controlled, short-term, single-chemical scenarios that regulatory safety assessments are typically modelled on. A growing body of scientific literature suggests this methodology may significantly underestimate real-world risk.
The question No More Glyphosate NZ is asking — and that more New Zealanders should be asking alongside them — is not simply whether glyphosate has been declared safe by a regulatory body. It is whether that declaration is keeping pace with what the science is actually finding. And it is whether the absence of evidence, in a country that isn’t systematically looking, should be confused with evidence of absence.
How to Reduce Your Glyphosate Exposure in New Zealand
While the policy conversation catches up with the science — and the monitoring infrastructure catches up with the risks — there are practical steps New Zealanders can take to reduce their own and their family’s exposure.
Choose organic where you can. Glyphosate enters the body primarily through food, particularly grains, legumes, and conventionally farmed produce. Certified organic food cannot be treated with glyphosate. If a fully organic diet isn’t financially feasible, prioritise the foods most likely to carry residues: oats, wheat products, bread, and processed grain-based foods.
Filter your drinking water. Glyphosate has been detected in waterways and tap water in agricultural regions. A high-quality water filter — reverse osmosis or activated carbon — significantly reduces exposure from this source. This is particularly relevant for households in rural and horticultural areas.
Cook at home more often. Processed and restaurant foods are more likely to contain ingredients sourced from conventionally farmed, glyphosate-exposed crops. Cooking from whole, identifiable ingredients gives you more control over what you’re actually consuming.
Support your gut microbiome. Since glyphosate appears to disrupt the gut microbiome, actively supporting it matters. Fermented foods — kefir, sauerkraut, kimchi, plain yoghurt — and fibre-rich whole foods help maintain the microbial diversity that underpins metabolic and immune health.
Ask questions. Of your GP. Of your local council. Of your supermarket. Of your elected representatives. What are the glyphosate residue levels in the food your family eats? What is being monitored in your local waterways? What does your region’s agricultural spray programme look like, and how close does it come to schools, playgrounds, and water sources? What research is New Zealand doing on its own population?
Glyphosate, Fatty Liver Disease and the Pattern of Regulatory Lag
Fatty liver disease does not develop overnight. Neither does the scientific consensus that a widely used chemical may be contributing to it.
The tobacco industry spent decades funding studies designed to cast doubt on the link between smoking and lung cancer. The lead industry insisted leaded petrol was safe long after the evidence suggested otherwise. The pattern — commercial interests, regulatory inertia, and a widening gap between what science is finding and what the public is being told — is historically familiar.
That does not mean glyphosate is definitively the next tobacco. The science is not yet at that point of certainty, and it would be dishonest to claim otherwise. But the trajectory of the evidence is clear enough, and the stakes — the liver health of over a million New Zealanders, the long-term metabolic health of our children, the disproportionate burden falling on Māori and Pacific communities — are high enough that waiting for absolute proof before asking harder questions seems like precisely the wrong approach.
New Zealand has long prided itself on being clean and green. Our food, our water, our land — these are not just marketing slogans. They are things worth protecting, and worth scrutinising honestly.
Right now, the evidence suggests we should be looking much more carefully at what we are putting on that land. And what it may be doing to the people — and the children — living on it.
* A note on New Zealand prevalence estimates New Zealand does not have a national MASLD registry, so exact figures are not available. The estimate of one to one-point-three million New Zealanders living with fatty liver disease is derived by applying international prevalence rates (25–35% of adults) to New Zealand’s population of approximately 5.3 million, cross-referenced with known local rates of obesity and type 2 diabetes. These are informed estimates consistent with international epidemiology, not directly measured figures. See: bpacnz — Chronic Liver Disease in New Zealand and Healthify — Fatty Liver Disease.
Key studies and sources referenced in this article:
- Environmental Toxicology and Pharmacology, Volume 116, June 2025 — 42-study meta-analysis on glyphosate and fatty liver disease
- Environmental Health Perspectives, March 2023 — CHAMACOS longitudinal study on childhood glyphosate exposure and adolescent health outcomes
- Clinical Gastroenterology and Hepatology, 2019 — UC San Diego biopsy study on glyphosate exposure and liver disease severity
- Clinical and Molecular Hepatology, 2025 — Global epidemiology of MASLD
- Miao et al., Southampton/Wenzhou, 2024 — Current status and future trends of the global burden of MASLD
- Lancet Regional Health Europe, 2025 — Diagnosis rates and economic burden of undiagnosed MASH across the US, UK, Germany, and France
- Women’s Health, 2025 — PMC — MASLD and women’s health
- bpacnz, 2022 — Key causes of chronic liver disease in New Zealand
- Healthify NZ — Fatty liver disease overview for New Zealand
- University of Otago — Edgar Diabetes and Obesity Research Centre — NAFLD dietary triggers and treatment approaches
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