Is Glyphosate Making Us Sick? What the Science Says and What You Can Do

by Nicole Flynn, NTP, RHP, BCHN (candidate)

There is a chemical hiding in your breakfast cereal, your morning oats, your bread, and even your honey. Chances are you’ve never thought twice about it. It doesn’t have a taste or a smell. Regulators say the amounts we consume are safe. And yet, MIT senior research scientist Dr. Stephanie Seneff has spent years building the case that this chemical,  glyphosate, the active ingredient in Roundup weed killer, may be quietly undermining human health in ways we are only beginning to understand.

Her 2021 book Toxic Legacy: How the Weedkiller Glyphosate Is Destroying Our Health and the Environment is a sweeping, meticulously researched deep dive into glyphosate’s potential role in some of the most pressing health crises of our time. Every health-conscious person deserves to know what’s in it.

A Chemical with Three Lives

Most people know glyphosate as the herbicide in Roundup. But here’s something that should give us pause: glyphosate has been patented not once, but three times. In the early 1960s, it was first patented as a chelating agent, a chemical that strips mineral deposits from industrial pipes and boilers. In 1968, Monsanto patented it as an agricultural herbicide. And in the early 2000s, it was patented a third time, as an oral antibiotic.

That third patent matters enormously. Because it means glyphosate doesn’t just kill weeds, it kills bacteria. And that includes the trillions of beneficial bacteria living in your gut.

The official reassurance has always been that glyphosate is safe for humans because it targets the “shikimate pathway,”  a metabolic process found in plants but not in human cells. The problem, as Seneff points out, is that our gut microbes do use this pathway. They rely on it to produce tryptophan, tyrosine, and phenylalanine, three of the twenty essential amino acids that form the proteins of our bodies and serve as raw materials for serotonin, dopamine, and thyroid hormones.

It’s Everywhere; Including Places That Should Be Safe

Glyphosate isn’t only sprayed on GMO crops. Conventional wheat, oats, barley, rye, legumes, and oily crops like canola, sunflower, and flax are routinely sprayed with glyphosate as a “desiccant” right before harvest, to dry the crop for easier processing. This means that some of the highest glyphosate residues are found in non-GMO foods many people consider “healthy.”

And even choosing organic doesn’t fully protect you. Glyphosate is water-soluble, entering waterways across the country, drifting on wind, persisting in soil (one study found that 59% remained after 748 days), and showing up in animal manure used to fertilize organic fields. In 2017, the FDA tested 28 samples of honey, which of course is not a sprayed crop  and found that 100% of the samples contained glyphosate. It has also been detected in human urine and breast milk, and in the serum of newborns whose mothers were exposed.

What Glyphosate Does Inside the Body

Seneff’s book identifies several overlapping mechanisms by which glyphosate may be harming health. These are not simple, one-step processes  and that is precisely why they have been so difficult to pin down.

Your gut microbiome takes a direct hit. Lactobacillus and Bifidobacteria, among the most beneficial and health-protective bacteria in the gut, are also among the most sensitive to glyphosate. When these are suppressed, the resulting imbalance creates an opening for more harmful bacteria (Clostridium, Salmonella, certain E. coli strains) to thrive. The loss of beneficial bacteria also reduces butyrate, the key short-chain fatty acid that fuels colon cells and maintains gut barrier integrity, a disruption linked to Crohn’s disease, IBS, and leaky gut. Think of it this way: chronic daily exposure to glyphosate in food is like taking low-dose antibiotics every single day.

Your liver receives some of the highest glyphosate exposure of any organ, given its role as the body’s filter. Glyphosate disrupts cytochrome P450 (CYP) enzymes, which are critical for detoxifying hormones, drugs, and environmental chemicals. It also depletes glutathione, the body’s master antioxidant, not just by forcing the liver to use glutathione to neutralize glyphosate, but also by substituting for glycine within the glutathione molecule itself, rendering it dysfunctional. A 2020 clinical study found that people with biopsy-confirmed fatty liver disease had significantly higher urinary glyphosate levels than healthy controls, and those with more advanced disease had the highest levels of all.

Your hormones are also vulnerable. A 2020 scientific review found that glyphosate exhibited 8 out of 10 key characteristics of an endocrine disruptor. Seneff connects glyphosate to disrupted thyroid function, suppressed testosterone production, and inhibited aromatase, the enzyme that converts testosterone to estrogen. She also makes a compelling case for a link between glyphosate and PCOS, identifying three specific enzymes in steroid metabolism that are disrupted by glyphosate through glycine substitution.

Your nervous system is not spared either. Glyphosate may contribute to neurological harm through multiple pathways, including glutamate excitotoxicity in the hippocampus, cobalamin (Vitamin B12) deficiency, sulfate deficiency, and mitochondrial damage. Notably, glyphosate binds to manganese, a mineral essential for the enzyme that clears excess glutamate from the brain, which may explain why children with autism consistently show higher glutamate concentrations in their brains. A California study found that pregnant women living within 1.2 miles of glyphosate spray areas were 30% more likely to have children with severe autism.

Sulfate is one of the most underappreciated players in the story Seneff tells. Sulfate is critical for Phase II liver detoxification, for brain and nervous system function, for cartilage and skin health, and for cell membrane integrity. Glyphosate undermines sulfate availability by disrupting the gut bacteria that produce sulfur, blocking the enzymes that convert sulfur to sulfate, and binding to the minerals needed for sulfur metabolism. The result: even if you eat a sulfur-rich diet, your body may not be able to convert it into usable sulfate.

What You Can Do: Seneff’s Practical Message

In the final chapter of her book, Seneff shifts from mechanism to action. Her core message is that while we may not be able to completely eliminate glyphosate from our lives, we can meaningfully reduce our exposure and support our bodies’ ability to handle it. Here are the key strategies:

• Choose organic for your highest-exposure staples. Conventional wheat, oats, barley, corn, soy, and legumes carry the heaviest glyphosate loads. Swapping your bread, oatmeal, and pasta for organic versions is one of the highest-impact changes you can make.

• Prioritize rebuilding your microbiome. Since many of glyphosate’s most damaging effects flow through gut dysbiosis, eating whole foods, adding fermented foods (yogurt, kefir, kimchi, sauerkraut), and minimizing unnecessary antibiotics can help restore the bacterial balance that glyphosate disrupts.

• Address mineral status. As a chelator, glyphosate depletes zinc, copper, manganese, magnesium, cobalt, and iron, not just in your body, but in the crops themselves. Eating mineral-dense whole foods (leafy greens, nuts, seeds, quality meats, and seafood) and considering targeted supplementation if deficiencies are present is important.

• Support your liver and sulfation pathways. Cruciferous vegetables (broccoli, cauliflower, Brussels sprouts, arugula), adequate dietary protein, glycine-rich foods like bone broth and collagen, and sulfur-containing foods (eggs, onions, garlic) all help support the detox pathways that glyphosate burdens.

• Filter your water. A quality carbon or reverse-osmosis filter can meaningfully reduce glyphosate in your drinking water.

The Bottom Line

Whether or not every one of Seneff’s proposed mechanisms is ultimately validated by mainstream science, the overall message is hard to argue with: supporting foundational health systems and reducing your environmental burden is a low-risk, high-reward strategy. We don’t need certainty about every biological detail to make smarter choices about the food we eat and the products we buy.

If this information feels overwhelming, please know that you don’t have to figure it all out at once.  And you don’t have to do it alone. My work as a functional practitioner is to help clients translate exactly this kind of complex science into practical, realistic steps that fit their real lives. If you’d like support building a cleaner, more nourishing way of eating, I’d love to connect.

And if you want to go deeper, I highly recommend reading Toxic Legacy by Stephanie Seneff, PhD, for yourself. It will change the way you look at the food on your plate.