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Does Glyphosate Cause Celiac Disease? Actually, No!

By: Peter Olins, PhD on February 26, 2014.

A recent article by A. Samsel and S. Seneff, claims that exposure to the herbicide glyphosate (the active ingredient in Roundup®), is the cause of several diseases, especially celiac disease (Ref. 1). This has recently been causing quite a stir on the Internet, and is obviously of concern for celiacs. I have reviewed this article, together with a number of previous papers by Dr. Seneff, and I strongly believe that her claims are not supported by the current evidence. I cannot state this more strongly: this article appears to be an exercise in political activism and does not deserve to be in a legitimate scientific journal. In my opinion, this kind of alarmism is unethical and irresponsible.

Does Glyphosate Really Cause Celiac Disease? Actually, No!

Source: Interdiscip Toxicol. 2013 vol 6, pp159–184

So Many Claims, So Little Evidence

There are literally dozens of claims and ideas proposed in this article, all with very weak evidence or rationale. This article is a series of wild speculations, rather than a logical hypothesis based on the available research. This is not the place to go into a detailed critique (that would probably take days!), but briefly, here are a few examples of why I don’t consider this to be a valid scientific assessment.

Claim 1: “Celiac disease, and, more generally, gluten intolerance, is a growing problem worldwide, but especially in North America and Europe, where an estimated 5% of the population now suffers from it.” This is not true. While the prevalence of celiac disease has increased, the 2009/2010 estimate of prevalence of non-celiac gluten sensitivity in the general U.S. population U.S. is about 0.6% (Ref. 2).

Claim 2: “Celiac disease patients have an increased risk to [ sic ] Non-Hodgkin’s Lymphoma, which has also been implicated in glyphosate exposure.” This is only half true: the risk of Non-Hodgkin’s Lymphoma in celiac disease patients has declined dramatically over the past several years (Ref. 3). So, contradictory to the authors’ claim, there is no evidence for a link with glyphosate exposure (unless, of course, glyphosate prevents cancer!).

Claim 3: “Glyphosate is known to inhibit cytochrome P450 enzymes.” This is the main theme of the paper, since the authors argue that inhibition of P450 causes some kind of toxicity. This is deceptive! Glyphosate inhibits some P450 enzymes in plants, but for some reason, the authors fail to mention the most extensive study of these enzymes in mice and humans. In this case, three major human P450 enzymes are not inhibited by glyphosate (Ref. 4).

Claim 4: “Deficiencies in iron, cobalt, molybdenum, copper and other rare metals associated with celiac disease can be attributed to glyphosate’s strong ability to chelate these elements.” Again, this is deceptive. Yes, glyphosate can bind to a variety of metals, but no evidence is presented that this is relevant under real conditions found in the human digestive system.

What is Glyphosate, and Why is it So Popular?

Glyphosate is the active ingredient in the herbicide Roundup®, made by Monsanto Company, and has been on the market for about four decades. For several reasons, it is the most widely used herbicide around the world: 1) it is very effective when sprayed on a wide variety of weeds; 2) it is one of the safest substances used in agriculture (conventional or organic); and 3) it is cheap. In recent years, crops have been introduced that have been “genetically modified” (GMO) to be resistant to glyphosate. Weeds in these crops can be killed by glyphosate, while leaving the crops (typically corn, soybeans or canola) unaffected.

Understandably, this increased use of glyphosate has raised the question of whether it might be affecting our health. I try to follow this field closely, since I’m particularly interested in nutrition and its role in human health. I have found no scientific reason to conclude that the herbicide-resistant food crops on the market are any more or less safe than their herbicide-sensitive counterparts.

Is There Any Direct Evidence for a Connection Between Glyphosate and Celiac Disease?

The paper includes dozens of speculations, but offers surprisingly little evidence for a celiac disease connection. Only one figure in the paper shows any information about celiac disease. Figure 1 is a chart that compares the number of celiac disease hospital discharges with the reported glyphosate use on wheat—see the adjacent chart. Unfortunately, the sources of the data used for this chart were not provided, making it hard to verify. This is highly unorthodox: usually it is an absolute requirement to show how data were obtained for a scientific article!

A three-fold increase in hospital discharges for celiac disease diagnoses is shown; but this chart is deceptive: the number of biopsies is simply an indication of the number of diagnostic tests performed, not the overall prevalence of the disease. In fact, there is very little precise information about how the prevalence of celiac disease has been changing over time.

It is well known that doctors have performed more biopsies over the past few years, and thankfully, many more cases of celiac disease are now being successfully diagnosed. But this is not a measure of the overall prevalence of the disease in the general public. In fact, the latest estimate is that only about 15% of cases in the U.S. have been diagnosed (Ref. 2).

The information in the above chart does NOT provide evidence that glyphosate causes celiac disease. Since celiac disease takes years to develop, one would expect the increased level of exposure to occur years prior to seeing an effect. There is no reason to assume that glyphosate would trigger celiac disease “instantly”. If anything, the celiac disease and glyphosate  trends should not overlap!

Also, there is no evidence presented to show the actual levels of exposure to glyphosate exposure, and the authors fail to cite the most relevant study which measures this (such as Ref. 5).

No other data on celiac disease is presented in the article; instead, the authors go on to speculate about all kinds of other conditions, but these are not relevant to the main claim of the paper, and seem to be just a distraction.

Is This Article Even “Science” At All?

1. Samsel and Seneff make one of the most basic errors in science: they assume that if two things follow a similar trend, then there must be a cause-and-effect relationship. Wrong! The ideas in this paper are often distorted by presenting one single association, while neglecting to show other available evidence that would invalidate their assumptions. This is scientifically dishonest.

2. The authors also don’t grasp a basic concept in statistics that you can’t just search for every possible association, and then just highlight the one that happens to fit your preconceived ideas! (I’ll go into more detail about cause and effect at the end of the blog).

3. The authors also seem to be unaware of the simple concept that large doses of any substance are more toxic than small ones! This is Toxicology 101. Water and arsenic are both toxic, depending on the amount consumed. Giving test animals massive amounts of a substance is not the same as the effect of a minute trace of that substance that may inadvertently enter the human body; yet the authors fail to make the distinction. They also make no effort to discuss the known levels of exposure to traces of glyphosate, and how they compare to the available toxicology data. The one paper that they do mention (Ref. 6) involved treating human cells cultured in a dish with varying amounts of glyphosate. But they fail to point out that a toxic effect was only seen at a vastly higher level than would result from glyphosate in the diet—similar to the levels in a bottle of undiluted Roundup® herbicide, something that I would not recommend! My very rough estimate is that levels of exposure to glyphosate that we are exposed to could be at least 10,000-fold less than the amount used in the toxicology study.

4. “Prevalence” is not the same as “incidence”, but the authors seem to confuse the two. Prevalence of a disease is a measure of how common the disease is in the general population. For example, the prevalence of celiac disease is currently estimated to be about 1% in many countries. Incidence is a measure of how many new cases are being diagnosed in a given time period. In the case of celiac disease, only about 15% of the cases (prevalence) in the U.S. have been diagnosed. Fortunately, doctors are getting better at diagnosing the disease (incidence), and more people are being tested using an intestinal biopsy. This is good news. There is no reason to think that changes in glyphosate exposure would change how well celiac disease is diagnosed. The authors do not address changes in overall prevalence.

5. Glyphosate has been used as a herbicide for decades, and is one of the most extensively studied chemicals in our environment. But the authors fail to cite the literally hundreds of papers and reports that address the safety and biological activity of glyphosate. This leaves me with the impression that the authors have little interest in an objective analysis of the available information.

6. In this paper, the authors show a striking lack of curiosity about whether their ideas are actually TRUE or not! No experiments whatsoever are proposed that would be able to validate their ideas—or invalidate them. But this is the cornerstone of how actual science is done! Science involves first looking at the available information, then developing a hypothesis, and then designing a definitive experiment. It is as though the authors believe that systematic searching for potential associations is all that’s needed. This issue would surely have been rectified if the authors had chosen to collaborate with experienced experimental scientists in the relevant areas of disease and toxicology.

Who are the Contributors to This Paper on the Relationship Between Celiac Disease and Glyphosate?

Stephanie Seneff has a PhD in Electrical Engineering and works at the MIT Computer Science and Artificial Intelligence Laboratory. She appears to have shifted careers to apply her computing skills to analyzing publicly available databases of health information, especially for controversial topics such as vaccines, GMOs and glyphosate. As far as I can tell, she has no obvious experience in any of the biological sciences or toxicology, and has never published any biological research of her own. Given this lack of experience, it is remarkable that she typically chooses co-authors who also do not have biological research experience. Dr. Arthur Samsel, the co-author of this paper, is a retired consultant who worked at Arthur Little (again, with no obvious experience in biology). All the figures in this paper were created by Dr. Nancy Swanson, a physicist, formerly employed by the navy, and currently a company owner and expert in optical systems.

It is astounding that Dr. Seneff chose not to include either a toxicologist, an expert on glyphosate, or an expert in celiac disease research, as a co-author on this paper. The only person acknowledged for their input on celiac disease is Jennifer Moeny: no offense to Ms. Moeny, but I am not aware that she has ever been involved in any kind of scientific research, let alone celiac disease.

Stephanie Seneff’s work is funded by Quanta Computers, Taipei, Taiwan, under the auspices of the Qmulus Project, but I have not been able to learn more about this project, and how it relates to the current paper.

What Kind of a Journal is “Interdisciplinary Toxicology”? Where Can You Find This Paper?

This is surprisingly hard to answer. Dr. Seneff seems to make a habit of publishing in extremely obscure journals: most of her recent research is published in a journal called “Entropy”—not the place I would normally expect to see papers on environmental health or toxicology! The article by Samsel and Seneff apparently has a publication date of Nov. 11, 2013, and the journal is supposed to be free to the public. However, I can’t find this paper either on the journal website, in the PubMed database of biomedical research, or on Stephanie Seneff’s page on the MIT website. As far as I know, it is only available on an anti-GMO activist website, so it is not clear if it has actually been accepted for publication. (But see February 27, 2014 update, below).

Trends and Associations Do NOT Imply Cause-and-Effect!

On a lighter note, here is a great example of why it is important not to over-interpret trends. If you look hard enough, you can find two trends that match perfectly, even though they have nothing at all to do with one another. I wonder if Samsel and Seneff had seen this chart they would conclude that organic foods cause autism, or that people with autism are the major consumers of organic food? It’s always tempting to try to find something to blame for a particular disease or condition, but it’s important to be skeptical, unless the evidence is rock-solid.

The Real Cause of Autism? Yeah, Right!

Image Courtesy of jasonp55: http://www.reddit.com/user/jasonp55 — Image Link: http://imgur.com/1WZ6h

Conclusion: This is Not Really Science! There is No Credible Evidence for a Celiac-Glyphosate Connection

In my opinion, this is science of the lowest quality, apparently published in a questionable scientific journal.

Perhaps I have dwelled too much on this topic? This blog is definitely not meant as a personal attack, even though the language may be strong. However, I believe that it is vital to debunk false claims by anti-GMO activists, especially if they attempt to exploit the current public interest in gluten and celiac disease. Let’s hope that in this case, most people will realize that bizarre speculations belong in magazines next to supermarket checkouts.

(I thank my wife, Gillian Olins, PhD, for her helpful critique of this article).


Ref. 1: Samsel A & Seneff S. Glyphosate, pathways to modern diseases II: Celiac sprue and gluten intolerance. Interdiscip Toxicol. 2013 vol 6, pp159–184

Ref. 2: Rubio-Tapia et al. The prevalence of celiac disease in the United States. Am J Gastroenterol. 2012 Oct;107(10):1538-44. doi: 10.1038/ajg.2012.219. 

Ref. 3: Gao Y, et al. Lymphoma risk following celiac disease diagnosed in Sweden from the mid-1970s to the early 21st Century. Gastroenterology. 2009 January; 136(1): 91–98. 

Ref. 4: McLaughlin LA et al. Functional Expression and Comparative Characterization of Nine Murine Cytochromes P450 by Fluorescent Inhibition Screening. DRUG METABOLISM AND DISPOSITION (2008) Vol. 36, No. 7 1322-1331.

Ref. 5: Acquavella JF et al. Glyphosate Biomonitoring for Farmers and Their Families: Results from the Farm Family Exposure Study. Environ Health Perspect 112:321–326 (2004). doi:10.1289/ehp.6667

Ref. 6: Gasnier C et al. (2009). Glyphosate-based herbicides are toxic and endocrine disruptors in human cell lines. Toxicology 262: 184–191.

Update added February 27, 2014.

The article by Samsel and Seneff (Ref. 1) has just been added to the journal website, and can be found here: http://www.intertox.sav.sk/ITX_pdf/06_04_2013/10102-Volume6_Issue_4-01_paper.pdf

31 comments to Does Glyphosate Cause Celiac Disease? Actually, No!

  • Brian Chapman

    It was actually pretty easy to find on the journal’s website.


    • Peter

      Thanks, Brian.
      Yes, I checked last night, and they have just added 6 months worth of articles to the site. It’s good to have a real link for this paper.
      This journal is a little unorthodox, since the 5 senior editors all work in the same research institute in Bratislava, Slovakia. Maybe this is a good thing, maybe not. This journal appears to only have 4 issues a year, but these 5 editors all seem to be remarkably well represented in its pages, since the journal launched. For example, 50% of the Editor in Chief’s papers are in this “international” journal.

      Did you get a chance to read the Samsell/Seneff paper? Any comments?

  • Jonathan

    Maybe I’m missing something but the majority of the wheat crop is not treated with glyphosate for in-crop weed control. The authors are clueless as to the agronomics of growing wheat.

    • Peter

      Hi Jonathan,

      I was also puzzled about this, when I first read it.
      However, it turns out that glyphosate is sometimes sprayed on glyphosate-sensitive crops just before harvest, causing them to shrivel up and dry out. This apparently makes harvesting easier, and improves yield. This approach is especially used in countries with a wetter climate (e.g. the U.K.).

      Incidentally, moisture in crops is a real problem worldwide, since it promotes the growth of molds which can be be extremely toxic. This can lead to harvests that are unfit for consumption by humans or animals. In my opinion toxins from molds represent the most important food safety issue worldwide, but we don’t hear a lot about it. This area of research, is still in its infancy, and some of these toxins are very hard to detect. Many people tend to think about things from nature as being inherently safe, but in fact, some of the most toxic compounds on earth are actually produced by other organisms in our environment. Plant and fungi, for example are often locked in a kind of chemical warfare, with fungi trying to kill the plants, and plants retaliating with their own set of antidotes.

  • Jonathan

    Hi Peter;

    I work as agronomist, and would like to clarify a few of your points. Glyphosate is used preharvest on a limited number of cereal acres. This is not what I would consider a standard practice, although it is registered and on the label for use.

    Glyphosate’s intended use is not for “shrivel up and dry out”. It is applied preharvest after the crop has reached physiological maturity as a “harvest aid”. This means that the kernel of the wheat or cereal crop has black layered (30% moisture or less) and has biologically separated from the parent plant. The seed has reached full maturity.

    Using the term harvest aid; it is intended to be used to kill the green plant material (aka weeds) that remains in the field. This is to reduce the issues at harvest such as combine plugging.

    There are numerous fungicides on the market that are used to reduce the risk of toxins (i.e. fusarium head blight). Depending on the type of toxin and when it is identified in the food chain, it can be cleaned out of the grain using mechanical separation methods.

    • Peter

      Thanks, Jonathan.

      I make no claims to be an agronomist! I based my comments on a lengthy report that I found after a Google search:

      I think that Samsell and Seneff were trying to make the case that substantial amounts of glyphosate were entering the food supply because of the use of pre-harvest glyphosate or otherwise glyphosate-sensitive crops. I have no idea how widespread this practice is, but perhaps you could share some information?

      I did, however, look at a series of reports on the actual levels of glyphosate in bread in the U.K. over the past few years. These ranged widely, from undetectable to less than 1 ppm. This would indicate to me that the average intake of glyphosate from this source is quite small.
      As I stressed in my article, Samsell and Seneff provide no convincing evidence that such traces would be a reason for concern.

      • Jonathan

        Hi Peter;

        I read the links you had supplied and the issue of moisture transfer in grain from green material could be an issue in the UK wheat growing environment. The wheat management techniques used in Europe are much more intensive than those used in North America. This leads to more green plant matter at harvest, and where using a tools such glyphosate can help. In my practice I would suggest that there is limited acres (less than 10%) that would be treated in the manner suggested. The acres that are treated are mainly targeted for perennial weed control. I am unable to find data for other acres.

        I also noticed in the guide that glyphosate was used as a harvest aid for corn. This is more or less unheard of and would be ineffective in traited corn. Nature’s harvest readiness tool (aka frost) is used to even up the crop.

        Thank you for posting the article, I have shared it with others that were discussing the paper.

  • Jess

    Thank you for putting together your rebuttal to this article full of junk science that has been circulating through the Internet. I’ve received it from at least 2 dozen well intentioned people who do not know how to interpret it correctly. Now I can lead them to your post…

  • MaryM

    There’s absolutely no way this Samsel and Seneff escapade in creative writing saw a shred of review. I was reading along, and where they talk about figure 2 they say:
    “Figure 2 shows that there is a correlation between glyphosate application to corn and soy and the incidence of intestinal infections.” (pg 161) I go look at figure 2 (pg 162). Figure 2 is a graph with wheat.

    C’mon-multiple reviewers didn’t notice this? Really?

    • MaryM

      I just went to the site to see if the paper was the same (it wasn’t on the publishers site before, a lot of us looked. Their site had stopped updating months ago.)

      I found they have altered their paper (without noting the change):

      • Gillian

        I don’t think MIT is going to be too thrilled to learn that their prestigious research reputation is being dragged through the mud!

      • Peter

        Thanks for catching this, Mary—or should I say, Sherlock!

        This is very unorthodox: regular journals usually publish a simple separate “correction” page if an error was made. Publication is meant to be a fixed point, not a moving target. Can we expect to see more “updates” to this paper?!

  • Kathryn Kellison

    While this article on the link between celiac disease and glyphosates lacks integrity and evidence, there is also no proof that glyphosate doesn’t cause celiac disease. For you to say definitively in the title of this artlcle that it does not is just as suspicious.

    That glyphosate is or is not sprayed on wheat is also beside the point. Celiac disease’s mechanism is dependent upon a loosening of tight junctions in the epithelial lining of the small intestine. When foreign particles, like those of the proteins in gluten, migrate into the abdominal cavity and give the immune system fodder to attack them as foreign, that is where gluten proteins become confused with and the immune system attacks healthy tissue with molecularly similar proteins.

    The argument, which has yet to be proved or disproved, is that the action of glyphosate on the small intestine is to open up those tight junctions (the medical term here is intestinal permeability) and allow for the immune response to the leaking food particles.

    This action has implications for the other autoimmune diseases such as MS and diabetes 1 which have also greatly increased their prevalence as well. Our genetic makeup hasn’t changed in 60 years, it is still true that 20% of us are born with the HLA DQ2 and or HLA DQ8 genes that predispose someone to celiac disease. But it is a fact that celiac disease has increased by more than 400% since blood samples were taken by Fort Walton military officials in the late 50s. Clearly, something in our environment has led to this problem. All we know is that it occured between the late 50s and now. We don’t know how many or which combinations of factors are involved, but my guess is that it is a man-made problem. I”d prefer, as a consumer, that every chemical that goes into our food chain be properly tested for safety. I don’t think that’s unreasonable.

    [Second comment from Kathryn pasted here:]
    Here’s an article on the Mayo Clinic study that shows a definitive 400% increase in celiac disease: http://www.mayo.edu/research/discoverys-edge/celiac-disease-rise

    • Peter Olins

      Hi Kathryn - Thanks for your comments.

      From your response, am I right in thinking that your main objection is the title, rather than the actual critique of the Samsel/Seneff article?

      In biological science, it is formally impossible to “prove a negative”. This is different from the confidence that we have that 2+2 does not =5. However, if someone makes a claim (e.g. the Tooth Fairy is responsible for climate change), then they are responsible for making a convincing case. In other words, the presumption is “innocent, until proven guilty”.

      Anyone can speculate about the thousands of diseases that we have, and the tens of thousands of substances (including foods and supplements) that we are exposed to, and the hundreds of lifestyle changes that we have made over the past decades. This is not useful. There is no guarantee that anything in life is safe! What we CAN do is use our best judgement to identify the few most plausible ideas, and then test them. Samsel and Seneff did not present a plausible model to support their claim that glyphosate is “the main causal factor in this epidemic [celiac disease]”.

      I am as puzzled as anyone about why the prevalence of celiac disease has increased over the past few decades. I agree that “something in our environment has led to this problem”; however, while it’s tempting to try to find something to blame, a key part of science is starting with the premise, “I don’t know”.

      As you point out, hypotheses about the causes of celiac disease have been around for many years, including possible changes in intestinal permeability. While this particular idea seems plausible, so far, there has been surprisingly little evidence to support it. I cannot agree with your speculation that glyphosate “opens up intestinal tight junctions”. However, if you provide some evidence or rationale, I would be delighted to discuss it. This is not the place to go into a detailed analysis of all the possible mechanisms of celiac disease: my main purpose was to offer a critique of the Samsel/Seneff article, since it makes such radical claims.

      Please tell me what glyphosate safety studies you believe are missing. Do you know what has already been done? Every 10 years, the European Union reviews the safety of the pesticides that it has previously approved. They recently reviewed 300 glyphosate toxicology studies, including 150 new ones performed over the past decade. They also reviewed 900 scientific publications. The beauty of glyphosate is that it has been around for so long that we probably have more information about its safety than any other molecule I can think of! Glyphosate has taken over the herbicide market precisely because it is effective, safe and cheap. In fact, one byproduct of this is that the use of more toxic herbicides have declined substantially.

  • Kathryn Kellison

    Here’s an article on the Mayo Clinic study that shows a definitive 400% increase in celiac disease: http://www.mayo.edu/research/discoverys-edge/celiac-disease-rise

    • Peter Olins

      Hi Karthryn,
      Sorry for not responding sooner.
      I am not clear exactly what your point is. There is no doubt that the prevalence of celiac disease has been rising over the past decades; the question is, why. My blog is intended to debunk the extravagant claim that glyphosate is “the primary cause”.

  • Anne Temple

    Former US Navy staff scientist Dr. Nancy Swanson did studies:

    “Prevalence and incidence data show correlations between diseases of the organs and the increase in Genetically Modified Organisms (GMOs) in the food supply, along with the increase in glyphosate-based herbicide applications. More and more studies have revealed carcinogenic and endocrine disrupting effects of Roundup at lower doses than those authorized for residues found in Genetically Modified Organisms.”

    “The endocrine disrupting properties of glyphosate can lead to reproductive problems: infertility, miscarriage, birth defects, and sexual development. Fetuses, infants and children are especially susceptible because they are continually experiencing growth and hormonal changes. For optimal growth and development, it is crucial that their hormonal system is functioning properly.

    The endocrine disrupting properties also lead to neurological disorders (learning disabilities (LD), attention deficit hyperactive disorder (ADHD), autism, dementia, Alzheimer’s, schizophrenia and bipolar disorder). Those most susceptible are children and the elderly.”

    • Peter Olins

      Hi Anne,
      I do not understand the purpose of your comment: these are not “studies”, but appear to be quotes taken from the Internet that you have cut and pasted. They relate to the complex subject of GMO and glyphosate safety in general, and while these are important and interesting topics, they don’t seem relevant to my article. These quotes seem to show up mostly on anti-technology activist websites that are more interested in politics than a meaningful discussion of science. Do you have any specific comments? Is there something that is not clear, or that you disagree with?

  • Jim Verrier

    I greatly appreciate Dr. Olins article and welcome any and all criticism of any scientific claims in an effort to reach the truth. However, I am disappointed to find bias on both sides of these arguments and that both Samsel/Seneff & Olins brings emotion into this discussion. Samsel’s article is disappointing because of macking such bold claims without better data and more expertise associated with their work. And I am disappointed with Dr. Olin’s criticism because he also has chosen to cherry-pick his points and uses this to completely disregard some valid points or suspicions that Samsel brings up. For instance, what do the 3 major P450 enzymes in human do that are not affected by glyphoshate? And what do the other ‘major’ and non-major p450 enzymes in human do that are affected by glyphoshate? Is the P450 enzyme question invalid because 3 of these are unaffected? What about the recent journal article showing the link between glyphosate killing specific intestinal gut flora that was referenced by Samsel? I would appreciate more data, more studies, better questions, and less emotion from both ‘sides’ of this. The anti-GMO sides brings too much emotion, and frankly so does the pro-GMO side. More data please and more encouragement to answer unpopular questions that are not financially relevant to those that fund or back these studies, researchers or journals.

    • Peter Olins

      Thanks, Jim. You raise a number of interesting points.

      I was puzzled by your comment about “bias”. In your opinion, what were the one or two most compelling arguments that glyphosate causes celiac disease? The only bias that I have is skepticism: in science, an idea invalid unless it is supported by actual evidence or reasoning.

      Regarding emotion, I think it is totally appropriate to be angry when a pseudoscientific distortion of the scientific literature is used to promote a political agenda. Left unchallenged, these repeated distortions become part of the cultural mythology, especially since most people will not have the time or expertise to critically evaluate these bogus claims. My goal was to both set the record straight and to condemn this kind of behavior. While there are plenty of low-quality scientific papers on obscure topics, these will probably do little harm, since they won’t be read by the general public. However, I do become passionate when there is the possibility that public acceptance of a flawed paper could be exploited to undermine our use of modern technology, such as particular herbicides or genetically modified organisms.

      Regarding “cherry-picking”, as I stated in my blog, I picked a few examples to illustrate the poor quality of the Samsel/Seneff paper. I limited my critique in the hope that my article would be somewhat digestible. (But I assure you, I only scratched the surface!). A more thorough debunking could have taken many days or weeks—something that I had neither the time nor inclination to do, and which would have been extremely depressing. To me, the Samsel/Seneff paper is a classic example of a “Gish-Gallop” (http://rationalwiki.org/wiki/Gish_Gallop), where a flood of questionable claims is used in an attempt to overwhelm a meaningful discussion of a topic. The huge number of references cited by S/S give an illusion of gravitas, but I doubt that the vast majority of people reading the paper will check to verify if the citations actually support the claims made.

      Regarding the family of cytochrome P450 enzymes, this is a large group of proteins whose primary function is to metabolize a huge range of organic molecules that are naturally found in the diet, typically reducing their toxicity and/or increasing the rate at which they are excreted from the body. In addition, some P450 enzymes play an important role in transforming molecules that are produced within the body. There are a number of examples where blocking a P450 enzyme results in increased toxicity of a molecule, for example, the potentiation of some of the statin drugs in people consuming large amounts of grapefruit juice. The critical point, though, is that in order to have an effect, an inhibitor needs to be present at a sufficiently high concentration. S/S do not present evidence or a plausible argument that the traces of glyphosate in our diet are sufficient to significantly inhibit human cytochromes, nor do they provide a plausible argument for why this would trigger celiac disease in the first place.

      Regarding the recent paper on the antibacterial activity of glyphosate, the study S/S cited did not measure human gut bacteria under normal conditions (food + waste + trillions of other bacteria). Instead, they found that almost all species of CHICKEN bacteria in an ARTIFICIAL test were remarkably resistant to glyphosate. The only exception was one species, but inhibition was only seen at roughly 1000-fold higher levels of glyphosate than are normally found in humans. No evidence or reasoning was presented to suggest that this idea is relevant to the real world.

      It surprised me that the authors failed to ask the simplest of questions: “Are the ACTUAL levels of exposure to glyphosate anywhere close to their hypothetical toxicity speculations?”. I find it amazing that they failed to do some simple arithmetic, and failed to quote the relevant literature on exposure levels. My rough estimates are that their speculative mechanisms are thousands or even a million-fold off! Was this just ignorance on their part or bias? You be the judge.

      Regarding your comment that “more data” is needed, as a scientist, I’m always interested in more data, but what specific data do you think are needed? What are these “unpopular questions” that you refer to? To do an experiment, one needs to have a plausible hypothesis to test. There are already literally hundreds of papers on the biology and biochemistry of glyphosate: what strikes me is that we are fortunate that such an important molecule has such a remarkably safety profile.

      As an advocate for food safety and good nutrition, I am passionate about the use of the best available scientific information to help guide our lifestyle choices. There are literally thousands of molecules that enter our body for which we have little or no safety information: for example, plants produce a large number of chemicals that are used for defense—natural pesticides. At this point, I think that a focus on glyphosate is a distraction from some of the real questions about the role that molecules in our environment play in disease and health.

      I’m not sure that I agree with your characterization of this topic as a pro- versus con-GMO matter. Don’t forget, the S/S claim was about the role of a herbicide in celiac disease, and this was the focus of my blog. (This is probably not the place to get into a discussion of the larger topic of GMOs, even though this might be interesting). To me, what’s important is that the best available information and reasoning should be used to make rational choices, while accepting that every human activity has both potential benefits and potential risks. Sadly, low quality papers, such as the S/S one, seem to be designed to create fear rather than inform.

  • Mike


    My wife lived for fifty three years without any problems with gluten. During that time she only took one pill a day, for high blood pressure. She had a heart attack, and afterwords was put on more medication, plus a lot of supplements. That is when she first discovered she was gluten intolerant.

    Could the pills/supplements that she takes daily, more than a handful, have something to do with this? A large group of people take many medications daily lately (in the last 30 years); could this be the reason for the gluten intolerance epidemic? The pills/medications somehow altering the gut or gut bacteria making gluten hard to digest??

    • Peter Olins

      Thanks for your question, Mike.

      Yes, it’s very puzzling why the prevalence of celiac disease has increased so much over the past few decades. Obviously, something must have changed in our environment or diet, but nobody knows what, despite a lot of speculation. Some people develop CD as a child, but there are an increasing number of cases that are diagnosed in late adulthood. It’s not clear whether this is a new phenomenon, or just a result of better diagnosis. The good news is that most celiacs can live a healthy life as long as they stay on a strict GF diet.

      I, personally, share your HUNCH that the tremendous increase in the consumption in so-called “supplements” may have had some negative consequences, especially since they are typically not tested for safety or quality. But this is just a HUNCH, and I have no further evidence to support the idea. There is certainly not enough reason for her to change what she consumes without consulting her physician. Incidentally, celiacs commonly develop a variety of nutritional deficiencies as a result of poor absorption of nutrients, so a doctor will often prescribe vitamin and mineral supplements to compensate for this.

  • Mike


    Thanks for the response. For the sake of argument, let’s assume this IS a new phenomenon, not better diagnosis. Taking maintenance doses was not so common until the rise of the drug industry in the last 20 to 40 years. My parents and grandparents took no medications or supplements daily. Now it seems like most people, some even in their twenties, are taking a couple of medications a day. A lot of folks also take supplements. My question is this: What happens to all those pills and supplements after leaving the stomach? Imagine what a year’s worth of medications looks like in a pile on the floor; that’s a lot of non-food for the body to deal with. There is no bulk with these medications, and they don’t just disappear; and at least the filler in these pills has to be left somewhere. My feeling is that the small and large intestines are being coated, actually slimed, like water drain pipes. This could lead to difficulty in digesting hard to digest foods, like wheat.
    With all the variables involved, it makes it hard to figure out what’s going on with this. My wife is also an identical twin; and her twin has no problems with wheat, as my wife had no problems; until she started taking all the meds and supplements.
    Maybe it’s too simple of an explanation for this, maybe not.

    Thanks again,


  • Mike

    Hello Peter,

    Have you seen this?


    • Peter Olins

      Hi Mike,
      Was there anything in my blog that was not clear, or that you disagree with? I’d be glad to discuss.
      Whoever wrote the piece on the Mercola site either has not actually read the Samsell/Seneff paper, or doesn’t have a sufficient grasp of basic science concepts to be able to critique it. Very disappointing.

  • Deb Grove

    Great analysis although the original article is so bad that anyone who can read doesn’t have to do much to analyze this. No real evidence is presented anywhere in the article. Just suppositions and correlations pulled out of the air!

    • Peter Olins

      Thanks, Deb.

      It’s amazing how many websites are using the latest two papers from Samsel and Seneff as “definitive” evidence for the supposed dangers of glyphosate. The papers are incredibly long and badly written, and my hunch is that the vast majority of people will just read the titles and abstracts, and assume that the text actually supports the claims made.

      Even in the celiac disease community—where I would have expected a higher level of skepticism about alarming medical claims—there are still many people promoting the idea that glyphosate (and/or GMO-derived foods) explain the recent rise in the prevalence of CD.

  • Deb Grove

    And if it does, so be it! But show the evidence with proper experiments, not correlations! BTW I LOVE your graph of autism vs organic food sales! And I hope MIT makes a decision about whether such pulp fiction comes out of their institution.
    Director Genomics

  • Peter Ellis

    It is frustrating to read a polemic that damns authors for their political agenda, makes accusations of “bad science” and is clearly pushing its own agenda. Want to actually address the questions raised by Seneff and Samsel? Then design and conduct experiments appropriate for determining whether or not there is a cause and effect relationship between glyphosate and celiac disease.
    Actual science is not conducted by writing attacks. What purpose is truly served by a piece such as yours? It serves to threaten anyone who might try to actually verify the ideas Seneff and Samsel propose.
    They may be off target, but that needs to be determined through research, not diatribe.

    • Peter Olins

      Hi Peter,

      Thanks for your comments. You seem to object to the style of my article, rather than to whether the criticisms are valid. I laid out four examples of flaws in the Samsell-Seneff argument: did they make sense? Do you disagree?

      As I mentioned in my article, there are plenty more flaws that I could have brought up, but the article was already getting very long, and I was concerned that it would be indigestible—especially for a general audience. Would you recommend that I should write a follow-up article with further detail? (If you are truly interested in learning more about this topic, feel free to contact me privately).

      I don’t understand your proposal for designing experiments. I think you have got things backward: it’s the responsibility of anyone who has a radical idea (such as Samsell and Seneff do) to present it in the light of all the available evidence—not my responsibility. Scientists typically design an experiment if they think that a hypothesis might actually be true. For example, if I thought that the moon might be made of blue cheese, I could design experiments to test my idea. But I’m pretty sure it’s made of rock. More specifically, since there are literally thousands of factors that have changed in our environment over the past few decades, what possible rationale could I have for choosing to investigate glyphosate exposure as the “most important factor” in causing CD—which is what S&S claim? Perhaps you have some ideas: if so, I’d be glad to discuss them.

      I was puzzled by your statement that “actual science is not conducted by writing attacks”. I disagree. In science, getting a paper published is just the first step: the real peer-review begins once the larger community has the opportunity to discuss and criticize. This process is essential for weeding out flawed ideas, logic or data. From your comment, I suspect that you may not have experienced the lively, and sometimes heated, debate that commonly occurs when radical hypotheses are presented.

      An important aspect of critique by peers is that they may be able to point out information that the original authors were unaware of. This is particularly relevant in the case of S&S, since they failed to cite literature or information that would contradict their ideas. I truly believe that they could have avoided embarrassment if they had chosen to collaborate with scientists actually working in the relevant fields of research.

      Finally, you seem to object to my motivation (agenda), but you don’t actually say what you think this is, so it’s hard to respond. I had two main reasons for writing this article: 1) I wanted to help calm the current alarm in the celiac community about possible causes of their disease, and 2) I wanted to debunk poor quality “science”.

      I have read literally thousands of published papers and abstracts over the past decade: some were of high quality; some were not. But a tiny handful stand out because they make outrageous claims, with little evidence or reasoning. Often they are published in obscure journals, where they may not be subjected to tough scrutiny. Normally, I would dismiss them, and assume that they would rapidly recede into obscurity, because they are of little interest to the community. However, in this case, the S&S paper seems to have achieved a certain notoriety on the Internet, and I thought it was important for someone to set the record straight.

  • Jacquelyn Rook

    Dear Peter Olins,

    I like your writing. You are very lucid. I like the way you see incoming comments for what they mean, the way you can see how things are not related even though someone claims they are, and above all I admire your unfailing courtesy and openness to civil discussion.

    Even if you are wrong (and I am by no means implying that I think you are), I thank you very, very much for your calm presence.

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