Being the very aware reader that you are (otherwise you wouldn’t be here), you will have no doubt wondered at some point whether genetically modified crops affect breast cancer risk. I have looked deeply into that subject and this article shares what I have found.

You would have to be a hermit living in a cave not to be aware of the fact that our food has changed drastically in the past few decades. In any given household you can find at least one thing in the food pantry that previous generations would not have considered to even be food.

Between highly processed foods, food additives, pesticide residues and other environmental exposures, our modern food environment is very different from that of previous generations. Once upon a time, all food was “organic”.

There is now a groundswell of people educating themselves about food quality and nutrition. Consumers around the world are increasingly choosing organic food, with global retail sales reaching record highs. Many shoppers are also deliberately avoiding genetically modified foods. But do we need to? Let’s dive in.

What Are Genetically Modified Organisms?

Genetically modified (GM) organisms are living organisms whose genetic material has been deliberately altered using biotechnology in ways that would not occur naturally through conventional mating or natural recombination. In some cases, a specific gene from one organism is introduced into another, even when the two organisms are unrelated. Other techniques can modify or edit existing genetic material.

This differs from the traditional cross-breeding methods farmers have used for centuries, in which plants are sexually crossed and their existing genetic material is recombined over successive generations.

Why Are Herbicides & Pesticides Part of the Conversation?

To understand some of the concerns surrounding GM agriculture, it is important to understand pesticides and herbicides. This is particularly relevant because two of the most widely used GM crop traits are insect resistance and herbicide tolerance, and these traits can significantly change how pesticides are used in agriculture.

Pesticides are substances used to prevent, control or destroy organisms that can damage crops or compete with them. The term includes insecticides, which target insects; herbicides, which target weeds; fungicides, which target fungi; and several other categories. Some pesticides are synthetic chemicals, while others are derived from naturally occurring substances or microorganisms. Their potential effects on human health and the environment depend on the particular pesticide, its formulation, dose and route of exposure.

Some insect-resistant GM crops contain genes derived from the soil bacterium Bacillus thuringiensis (Bt). These genes enable the plant to produce insecticidal proteins called Cry proteins. When susceptible insects consume the plant, the proteins are activated in the insect’s digestive tract and bind to specific receptors in the gut, ultimately disrupting the intestinal membrane and killing the insect.

Herbicide-tolerant crops are genetically engineered to withstand particular herbicides that would otherwise damage or kill the crop. One well-known example is the Roundup Ready system, in which crops are engineered to tolerate glyphosate. This allows farmers to apply the herbicide across a field while the crop survives and many susceptible weeds are killed.

The USDA reports that in the United States in 2025, 96% of soybean acreage, 93% of upland cotton acreage. and approximately 92% of corn acreage was planted with herbicide-tolerant genetically engineered varieties. [1]

What are the ramifications of this for our health?

In 2015, the International Agency for Research on Cancer (IARC), part of the World Health Organization, classified glyphosate as a Group 2A carcinogen – “probably carcinogenic to humans.” The classification was based on limited evidence of cancer in humans, sufficient evidence of cancer in experimental animals, and strong evidence of genotoxicity for both pure glyphosate and glyphosate-based formulations. Importantly, IARC’s classification describes the strength of evidence that a substance can cause cancer; it does not by itself determine the cancer risk associated with a particular level of exposure.

It is important to note that IARC’s classification was not a determination that glyphosate causes breast cancer specifically. The human evidence considered by IARC primarily concerned other cancers, particularly non-Hodgkin lymphoma. Since 2015, researchers have continued investigating whether glyphosate exposure may have particular relevance to breast cancer through hormonal, cellular and epigenetic pathways.

Glyphosate: The Chemical at the Center of the Controversy

Glyphosate is a broad-spectrum herbicide used to kill unwanted plants and is the active herbicidal ingredient in many products, including Roundup formulations. Its importance to the GMO discussion comes largely from the development of herbicide-tolerant crops, which were genetically engineered to survive applications of glyphosate while weeds are killed. This made it possible for farmers to spray glyphosate over entire fields without killing the crop.

One analysis of global pesticide-use data estimated that agricultural use of glyphosate increased almost 15-fold between 1995 and 2014, following the introduction of Roundup Ready herbicide-tolerant crops in 1996. [2] This does not mean that GM crops were solely responsible for the increase – glyphosate is also used on non-GM crops and in non-agricultural settings, and changes in farming practices have influenced its use.

Glyphosate has been the subject of considerable scientific debate because of questions about its potential effects on human health and the environment.

Of particular interest to breast cancer researchers are studies investigating whether glyphosate or its metabolites may influence hormonal signaling, oxidative stress, DNA methylation and other cellular processes that may be involved in cancer development. Some human and laboratory studies have raised concerns, while others have not found an association with cancer.

So, what has the research actually found when scientists have looked specifically at GMOs, glyphosate exposure and breast cancer? The answer is intriguing – but far from conclusive.

What Does the Research Say About GMOs and Breast Cancer?

Since my audience is primarily women who are either going through or have been through breast cancer, let’s start with BreastCancer.org – an organization whose mission is to help people make sense of the complex medical and personal information about breast health and breast cancer, so they can make the best decisions for their lives. BreastCancer.org currently states: “So far, no research shows that genetically modified foods affect cancer risk or cause long-term health problems.”

Okay, but it’s not that simple. It’s true that the research does not currently demonstrate that eating genetically modified foods causes breast cancer. However, there are more complicated questions around herbicide-tolerant GM crops, glyphosate exposure, endocrine disruption, epigenetic effects, and breast-cell biology. Let’s get into it.

A 2026 review [3] examined epidemiological evidence, previous reviews and international disease trends and found no consistent evidence linking GMO consumption with cancer overall, or site-specific cancers. The authors concluded that current evidence does not support consistent causal links between GMO consumption and cancer or other major chronic diseases.

This is consistent with the National Academies’ comprehensive 2016 assessment of genetically engineered crops and human health. [4] After reviewing a large body of evidence, the committee found no evidence supporting the hypothesis that foods from GM crops were associated with increased cancer incidence. The committee also emphasized that absolute certainty is rarely possible when assessing the long-term health effects of any food, and that scientific conclusions must be based on the evidence available.

But what does the research tell us specifically about glyphosate and breast cancer? That’s where the story becomes particularly interesting.

The GMO–Glyphosate Distinction

As discussed, some of the most widely grown GMO crops have been engineered specifically to tolerate herbicides. That means the question isn’t necessarily whether GM foods cause breast cancer, but whether herbicide-tolerant GMOs can contribute to greater herbicide use or exposure, potentially increasing exposure to glyphosate – a chemical that has been shown in laboratory research to produce biological effects relevant to breast cancer.

For example, a 2013 cell study [5] found that glyphosate could stimulate estrogen-receptor-related activity and proliferation in hormone-dependent breast cancer cells at certain concentrations.

A 2019 cell study [6] looked at repeated glyphosate exposure in non-cancerous human breast cells and found epigenetic changes, including reduced DNA methylation. In this study the researchers did not find that the treated cells themselves became tumors.

In a small prospective study reported in 2021 [7], women with the highest urinary concentrations of aminomethylphosphonic acid (AMPA), a major environmental breakdown product of glyphosate and a marker associated with glyphosate exposure, had approximately 4.5 times the odds of developing breast cancer compared with women with the lowest concentrations. The researchers emphasized that the finding needs confirmation in larger studies.

Another cell study published in 2022 [8] found that glyphosate could mimic some effects of estradiol in breast cancer cells, including activating estrogen receptor-alpha signaling (a pathway involved in breast cell growth) and increasing cellular proliferation (rapid growth) under the experimental conditions used.

A 2025 systematic review of preclinical research [9] looked specifically at glyphosate and breast cancer. Seven in-vitro (cell culture) studies met the review’s criteria, but no in-vivo (in a living organism) studies were identified. The review concluded that glyphosate showed weak estrogenic activity in ER-positive breast cancer cells, primarily involving estrogen receptor-alpha and changes in genes associated with proliferation and DNA repair. However, the authors emphasized that the available evidence remains limited, particularly because there is a lack of in-vivo research.

There’s also a 2026 laboratory study [10] which found that prolonged exposure to a low concentration of glyphosate increased cancer stem-like characteristics in both ER-positive and triple-negative breast cancer cell lines. Again, though, this is cell culture research, not a study in humans.

Taken together, these studies don’t prove that glyphosate causes breast cancer. They do, however, raise some interesting questions. Laboratory research has shown that glyphosate can interact with estrogen-related pathways, alter gene expression and epigenetic patterns, and affect characteristics associated with cancer-cell behavior. A small human study has also found an association between higher urinary AMPA levels and breast cancer odds. But laboratory findings are not the same as evidence of disease in humans, and the human research remains limited.

In other words, the science is not saying “glyphosate causes breast cancer.” It’s saying that there are biological signals worth taking seriously, and worth investigating much more thoroughly.

Glyphosate and Other Cancers and Gut Microbiome Issues

I feel compelled to share a few other areas of research involving glyphosate, even though they are not directly related to breast cancer. These studies don’t prove that glyphosate causes these conditions, but they do add to the scientific questions surrounding long-term exposure.

Glyphosate and Non-Hodgkins Lymphoma

One of the cancers that has received considerable attention in glyphosate research is non-Hodgkin lymphoma (NHL), a group of cancers affecting the lymphatic system.

A 2008 Swedish population-based case-control study [11] involving more than 1,900 participants found that people reporting glyphosate exposure had approximately twice the odds of developing NHL compared with those without exposure. Among people with more than 10 years of latency between exposure and diagnosis, the odds were approximately 2.3 times higher. The researchers also found increased associations for certain NHL subtypes, including small lymphocytic lymphoma/chronic lymphocytic leukemia. Importantly, this was an observational study, so it could identify an association but could not establish that glyphosate caused the cancer.

A 2014 systematic review and meta-analysis [12] examined almost three decades of research involving occupational pesticide exposure and NHL. The researchers found positive associations between NHL and several pesticide groups, and reported an association between glyphosate exposure and B-cell lymphoma. The findings, however, varied according to the type of pesticide and lymphoma subtype, with the authors calling for additional research.

Since then, the evidence has remained mixed. A 2019 meta-analysis [13] reported a 41% increase in NHL risk among people in the highest-exposure groups for glyphosate-based herbicides. However, a 2021 updated meta-analysis [14] found no statistically significant increase in NHL risk with ever-exposure to glyphosate, although it did find a modest association with diffuse large B-cell lymphoma. In other words, there is enough evidence to keep the question open, but not enough to say that glyphosate exposure causes non-Hodgkin lymphoma.

Glyphosate and the Gut Microbiome

This next area is particularly interesting because our understanding of the gut microbiome has changed dramatically over the past decade. Because we now seem to be suffering a plethora of digestive disorders such as inflammatory bowel disease, irritable bowel syndrome, celiac disease, gluten intolerance, and other gut microbiome disruptions, I felt it important to include this information.

There have been numerous animal and laboratory studies investigating whether glyphosate can alter the composition and function of gut microorganisms. Studies in mice and rats demonstrate that glyphosate exposure can reduce beneficial gut bacteria and induce inflammatory responses. [15]

A 2023 study [16] in mice specifically examined relatively low-dose glyphosate exposure, including a dose approximating the U.S. acceptable daily intake. The researchers found changes in gut microbial composition, including reductions in certain bacteria such as Bifidobacterium and Lactobacillus, along with changes in microbial pathways involved in short-chain fatty acid production. These changes were accompanied by increases in markers of intestinal inflammation and alterations in gut immune cells.

These findings are intriguing because they suggest a possible biological pathway through which glyphosate exposure could influence the gut ecosystem and intestinal immune function. And while these studies aren’t specifically about breast cancer, the gut microbiome is increasingly recognized as an important part of overall health, including immune regulation, inflammation and the way the body processes certain compounds.

My Thoughts on GMOs

After looking carefully at the research, I don’t believe the evidence supports saying that GM foods themselves cause breast cancer. The more complicated question is what happens when certain genetically engineered crops are paired with intensive herbicide use, particularly glyphosate.

There is laboratory evidence that glyphosate can affect biological pathways relevant to breast cancer, including estrogen signaling, gene expression and epigenetic processes. There are also intriguing – although still limited – human studies involving glyphosate or its metabolites and breast cancer, as well as research into glyphosate’s potential effects on the gut microbiome and other health outcomes. That is enough to make me personally cautious.

I choose to avoid genetically modified foods wherever reasonably possible, because I don’t see a compelling reason to deliberately add another potential environmental exposure to my diet when non-GMO alternatives are readily available.

 If you feel the same way, there are some relatively simple things you can do.

Let Your Wallet Do the Talking

We vote with our dollars every time we shop. If consumers consistently choose organic and non-GMO foods, manufacturers and farmers have an economic reason to respond.

Here are some practical ways to reduce your exposure to GM foods.

In the United States

1. Choose certified organic foods when possible.

Under USDA organic standards, genetic engineering is one of the prohibited production methods. Certified organic crops therefore cannot be produced using genetic engineering.

Organic certification also gives you something that simply looking for a “natural” claim does not: a regulated production standard.

2. Look for the USDA Bioengineered Food disclosure.

Under the National Bioengineered Food Disclosure Standard, foods that meet the USDA definition of a bioengineered food may disclose this in several ways. Look for wording such as “Bioengineered food” or “Contains a bioengineered food ingredient,” the USDA bioengineered symbol, or instructions for accessing the disclosure electronically or by text message.

One important caveat: the U.S. disclosure system is not identical to a simple “GMO yes/no” system. Highly refined ingredients derived from crops such as corn, soybeans or canola may not require a bioengineered disclosure when the modified genetic material is no longer detectable.

3. Look for a credible non-GMO certification.

The Non-GMO Project Verified butterfly is one voluntary certification consumers may encounter on packaged foods. If avoiding genetically engineered ingredients is important to you, a third-party non-GMO certification can make shopping easier.

In Australia and New Zealand

GM foods and ingredients are regulated by Food Standards Australia New Zealand (FSANZ), while the Office of the Gene Technology Regulator (OGTR) regulates the environmental release of GMOs in Australia.

There are currently no fresh whole GM fruits or vegetables in the Australian or New Zealand food supply. However, processed foods can contain approved GM ingredients derived from imported crops such as soy, corn and canola.

Australia currently has five GM crops approved for cultivation: cotton, canola, Indian mustard, banana and safflower. New Zealand has no GM crops approved for cultivation.

Approved GM foods and ingredients are generally required to carry the words “genetically modified” on the label when they contain novel DNA or protein or have an altered characteristic. There are some exemptions, so the labeling system is not completely universal.

For Australians and New Zealanders, the FSANZ website is a much more reliable source for checking the regulatory status of a particular GM food than relying on a general-purpose food app.

In Europe

The European Union has a stringent regulatory system for genetically modified foods and crops. GM foods and feed must undergo an authorization process involving risk assessment, and approved GM foods are subject to traceability and labeling requirements.

It is not correct, however, to say that GM foods are completely absent from the European food supply. The EU authorizes certain GM crops for import and use in food and animal feed. For example, in December 2025 the European Commission authorized or renewed several GM maize, soybean and oilseed rape products for food and feed use, although those particular authorizations did not permit cultivation within the EU.

So, if you live in Europe and want to minimize GM foods, look for products carrying the required GM labeling and consider voluntary “GM-free” certifications where available.

The 10 GMO Crops You May Encounter in the U.S. Food Supply

These may not be the most common GMO crops, but they are the ones you are most likely to encounter in the U.S. Some are grown extensively, while others are much less common.

1. Soybeans – One of the world’s most extensively genetically engineered crops. In the U.S. in 2025, about 96% of soybean acreage was planted with herbicide-tolerant varieties. GM soy is widely used to produce soybean oil, soy protein, lecithin and animal feed.

2. Corn (maize) – Extensively genetically engineered for traits including herbicide tolerance and insect resistance (Bt). Corn-derived ingredients include cornmeal, cornstarch, corn oil, corn syrup and high-fructose corn syrup.

3. Canola (rapeseed) – Much of the U.S. canola crop is genetically engineered, primarily for herbicide tolerance. Canola oil is widely used in cooking oils, dressings, margarine and processed foods.

4. Sugar beets – Most U.S. sugar beet production uses genetically engineered, primarily herbicide-tolerant varieties. Refined sugar from sugar beets is sucrose, chemically identical to sucrose from conventional sugar beets or sugar cane.

5. Alfalfa – Genetically engineered alfalfa is primarily herbicide-tolerant and is used overwhelmingly as animal feed, particularly for cattle.

6. Papaya – One of the more interesting GMO foods because virus-resistant GM papaya was developed to combat papaya ringspot virus. It is grown commercially, particularly in Hawaii.

7. Potatoes – Several genetically engineered potato varieties have been developed with traits including resistance to bruising and browning, reduced formation of certain compounds during cooking, and resistance to pests or disease.

8. Summer squash – One of the earliest commercially available GM vegetables. Certain varieties have been engineered to resist several plant viruses. It remains relatively uncommon compared with major GM commodity crops.

9. Apples – Certain varieties have been genetically engineered to resist browning after being cut, helping reduce food waste.

10. Pink pineapple – “Pinkglow” pineapples were developed to produce pink flesh by increasing lycopene levels. They are a much less common GMO food than corn, soy or canola.

The FDA currently lists these and several other genetically engineered crops as available in the U.S. food system, including cotton and additional newer bioengineered crops.

What About Ingredients in Processed Foods and Supplements?

Many of these ingredients can be produced using microorganisms, enzymes or agricultural raw materials that may themselves be genetically engineered. But the ingredient name alone does not tell you whether a particular product came from a GMO source.

For example, maltodextrin can be made from corn, and citric acid and xanthan gum can be produced through fermentation. Whether the particular ingredient in your product is derived from genetically engineered material depends on the manufacturer’s sourcing and production methods.

If you want to minimize GMO exposure, don’t assume that every ingredient on one of these internet lists is automatically a GMO. Instead, look for a certified organic or credible non-GMO certification, or contact the manufacturer and ask about the source of the ingredient.

For me, this comes back to the same simple principle: When you have a choice, choose the cleanest, least chemically intensive food you can reasonably afford – and let your wallet do the talking.

If this article was helpful, you may also enjoy these articles on Substack (another helpful resource where I post more regularly):

• From Anxiety to Clarity: Coping with Fear After a Breast Cancer Diagnosis

• When Breast Cancer Treatment Leaves You Dry “Down There” – Natural ways to ease vaginal dryness and improve comfort during endocrine therapy.

• How Long After Chemo Will I Feel Better? – Understanding recovery after chemotherapy and what you can do to support healing.

• Healing Beyond the Physical: Why Spirituality Matters on the Healing Journey – Looking after your emotional and spiritual wellbeing alongside your physical recovery.

References:

[1] USDA Report – Adoption of Genetically Engineered Crops in the United States – Recent Trends in GE Adoption – https://ers.usda.gov/data-products/adoption-of-genetically-engineered-crops-in-the-united-states/recent-trends-in-ge-adoption

[2] Trends in glyphosate herbicide use in the United States and globally – https://pmc.ncbi.nlm.nih.gov/articles/PMC5044953/

[3] Genetically modified foods and human health: a comprehensive review and cross-national time-trend analysis – https://pubmed.ncbi.nlm.nih.gov/41772782/

[4] Human Health Effects of Genetically Engineered Crops – https://www.ncbi.nlm.nih.gov/books/NBK424534/

[5] Glyphosate induces human breast cancer cells growth via estrogen receptors – https://pubmed.ncbi.nlm.nih.gov/23756170/

[6] Glyphosate Primes Mammary Cells for Tumorigenesis by Reprogramming the Epigenome in a TET3-Dependent Manner – https://pubmed.ncbi.nlm.nih.gov/31611907/

[7] Pilot Study on the Urinary Excretion of the Glyphosate Metabolite Aminomethylphosphonic Acid and Breast Cancer Risk: The Multiethnic Cohort Study – https://pmc.ncbi.nlm.nih.gov/articles/PMC8044054/

[8] Glyphosate mimics 17β-estradiol effects promoting estrogen receptor alpha activity in breast cancer cells – https://pubmed.ncbi.nlm.nih.gov/36379430/

[9] Glyphosate as an Emerging Environmental Pollutant and Its Effects on Breast Cancer Cell Proliferation: A Systematic Literature Review of Preclinical Evidence – https://pubmed.ncbi.nlm.nih.gov/41600575/

[10] Long-term exposure to N-(phosphonomethyl)glycine is associated with cancer stem cell-like properties in hormone-responsive breast cancer cells – https://pubmed.ncbi.nlm.nih.gov/42025940/

[11] Pesticide exposure as risk factor for non-Hodgkin lymphoma including histopathological subgroup analysis – https://pubmed.ncbi.nlm.nih.gov/18623080/

[12] Non-Hodgkin lymphoma and occupational exposure to agricultural pesticide chemical groups and active ingredients: a systematic review and meta-analysis – https://pubmed.ncbi.nlm.nih.gov/24762670/

[13] Exposure to Glyphosate-Based Herbicides and Risk for Non-Hodgkin Lymphoma: A Meta-Analysis and Supporting Evidence – https://pmc.ncbi.nlm.nih.gov/articles/PMC6706269/

[14] Exposure to glyphosate and risk of non-hodgkin lymphoma: an updated meta-analysis – https://pmc.ncbi.nlm.nih.gov/articles/PMC8223940/

[15] Glyphosate exposure induces inflammatory responses in the small intestine and alters gut microbial composition in rats – https://pubmed.ncbi.nlm.nih.gov/32045792/

[16] Low-dose glyphosate exposure alters gut microbiota composition and modulates gut homeostasis – https://pmc.ncbi.nlm.nih.gov/articles/PMC10330715/

Other Resources:

https://www.naturalhealth365.com/DARK-Act-gmo-breast-cancer-1534.html

Separating the Empirical Wheat From the Pseudoscientific Chaff: A Critical Review of the Literature Surrounding Glyphosate, Dysbiosis and Wheat-Sensitivity – https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2020.556729/full