Weed Killer Roundup: To Blame for Celiac and Gluten Sensitivity?

There's no research suggesting a causal link to glyphosate

wheat harvest
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Could exposure to glyphosate, the active ingredient in the weed killer Roundup, cause celiac disease or non-celiac gluten sensitivity? Two scientists argue in a research review that glyphosate could be to blame... but it's not clear they've proven their case.

The researchers, consultant Anthony Samsel and Massachusetts Institute of Technology senior research scientist Stephanie Seneff, theorize in the journal Interdisciplinary Toxicology that "glyphosate [Roundup] ... is the most important causal factor in this epidemic."

However, their research hasn't been backed up by others in the field. While it's not clear what, exactly, is causing spikes in the diagnosis of celiac disease and non-celiac gluten sensitivity, possible reasons for the increases include: better awareness and detection of the conditions, increases in the gluten content of wheat, and increases in the amount of wheat consumed in many people's daily diet.

Argument for Roundup's Role in Celiac, Gluten Sensitivity

Roundup (glyphosate) is produced by Monsanto Company, and is used extensively in farming. So-called "Roundup-ready crops," which are crops designed to withstand application of glyphosate so that the chemical can be used to kill off weeds in fields where the crops are grown, include: corn, soybeans, canola, cotton, sugar beets, and alfalfa. 

Contrary to popular belief, there's no "Roundup-ready" version of genetically modified wheat on the market right now (for more detail on this, see: Is genetically modified wheat causing increases in gluten issues?).

However, it is common practice among farmers to spray their wheat crops with glyphosate immediately prior to harvest—doing so actually kills the plant, which speeds the required drying of the grain. This is called "dessication." This practice makes it easier for farmers to time when they harvest their wheat crops, and allows for more uniform drying.

Samsel and Seneff note that the incidence of celiac disease and gluten sensitivity have risen dramatically worldwide, but especially in North America and Europe, and they blame the weed-killer glyphosate for this increase

They write: "Fish exposed to glyphosate develop digestive problems that are reminiscent of celiac disease. Celiac disease is associated with imbalances in gut bacteria that can be fully explained by the known effects of glyphosate on gut bacteria."

According to the authors, the characteristics of celiac disease indicate impairment of particular enzymes the body uses to process vitamin D (frequently low in people with celiac disease) and also to produce the digestive juices needed to digest food properly. Glyphosate is known to inhibit those enzymes, they write.

In addition, the authors note, "celiac disease patients have an increased risk to non-Hodgkin's lymphoma, which has also been implicated in glyphosate exposure. Reproductive issues associated with celiac disease, such as infertility, miscarriages, and birth defects, can also be explained by glyphosate."

Does RoundUp Cause Celiac or Gluten Sensitivity?

There's no question that glyphosate use is growing rapidly—its manufacturer, Monsanto Company, markets it in conjunction with genetically modified "Roundup-ready" seeds designed to resist glyphosate's effects. Farmers plant the genetically modified seeds and then use the glyphosate to kill weeds in the fields, knowing that the crops themselves will not be affected by the otherwise lethal herbicide.

It's true that dousing everything we grow and then eat in massive doses of chemicals (including glyphosate) may have some as-yet undiscovered health effects. However, the World Health Organization downplayed any cancer risks when it issued a report in 2016 stating that glyphosate is "unlikely to pose a carcinogenic risk to humans from exposure through the diet." 

No researchers have performed a study looking at whether glyphosate might cause celiac disease or non-celiac gluten sensitivity. Samsel and Seneff's paper did not involve any laboratory research; instead, it's hypothetical. 

A Word from Verywell

Despite the anecdotal evidence and reasoning laid out in Samsel and Senoff's paper, there's still no direct causal link between glyphosate and celiac disease or non-celiac gluten sensitivity.

The case they make is circumstantial, based on the reasoning that "if A causes B and B causes C, then A causes C." In this case, there are far too many other potential variables involved for the reasoning to hold up.

Is it possible that overuse of pesticides and herbicides—including glyphosate—could be contributing to our epidemic of celiac disease and non-celiac gluten sensitivity? Sure, it's possible. But researchers haven't shown that any link, let alone a causal link, exists.

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