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

Getty Images/Andy Sacks

March 5, 2014 — 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 new research review that glyphosate could be to blame ... but I don't think 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 ...

is the most important causal factor in this epidemic."

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) 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."

So what should you make of all this?

Well, 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.

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."

Obviously, dousing everything we grow and then eat in massive doses of toxic chemicals (including glyphosate) can't be good for us, and likely has some as-yet undiscovered health effects. In fact, the World Health Organization (WHO) said in March 2015 that a review of the medical literature indicates glyphosate "is probably carcinogenic to humans," meaning WHO suspects it causes cancer.

But 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 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." It's been a long time since I took Logic in college, but this reasoning doesn't hold up. In this case, there are far too many other potential variables involved.

Do I think it's 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 could. But do I think they've proved a causal link? Not based on this research paper.

There's clearly much more work to be done on this issue, but I urge you to view this paper as theory, not fact.

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