The Gluten Nocebo Effect

The same researches who suggested gluten intolerance apart from celiac disease could be the cause of a horde of troublesome symptoms have recently suggested that gluten intolerance was likely an incorrect conclusion.  The initial research conclusions lead tons of doctors to recommend and normal people to adopt a gluten free diet in hopes of improving their health in general or addressing specific symptoms.

But the smoking gun was never found.  What biological interaction between this particular protein (gluten) and the digestive system was causing disagreeable conditions? Most diseases attack healthy cells. Or intolerances and allergies produce some sort of inflammation as an autoimmune response. But no such object was found for gluten intolerance. So like good researchers, another study was proposed to see if gluten could be rigorously determined to be  as a trigger for gastrointestinal symptoms.

An extraordinarily rigorous nutritional  study was conducted by Peter Gibson and Jessica Biesiekierski at Monash University in Austrailia. The details of the study included completely controlled diets starting with a baseline diet devoid of all know symptom triggers and then  adding and subtracting gluten and other triggers all with fecal and urine samples being taken the whole time. Additionally it was a double blind study where the participants didn’t really know the truth about what they were eating. The study revealed that participants reported a worsening in symptoms for ALL treatment diets whether they contained gluten or not. This worsening of symptoms was even reported for the placebo diet which was actually identical to the baseline diet!

These findings indicate that it’s not gluten content in food that causes symptoms but rather the psychological expectation that a gluten will cause symptoms! The name for this phenomenon is the nocebo effect. It’s similar to the placebo effect in that it is completely psychological in nature based purely on expectations of the patient. The distinction between the two is that in the nocebo effect the patient expects the treatment to cause harm even if it doesn’t contain anything harmful. Case in point, tell somebody with gluten intolerance that they will be eating a diet containing gluten, they will experience gluten intolerance symptoms whether or not the diet actually contained gluten.

So much for gluten intolerance. BUT a large number of people are still experiencing unpleasant GI symptoms who were not part of this study and didn’t know if gluten was causing it or not and have felt better by removing gluten from their diet. Gibson’s study did suggest some positive information in addition to the nocebo discovery. The baseline diet used was a low FODMAP diet. FODMAPs are short chain carbohydrates (oligosaccharides), disaccharides, monsaccharides, and related alcohols that are poorly absorbed in the small intestine. I don’t know those fancy words that wikipedia uses, but I recognize the poorly absorbed in the small intestine part. And most gluten free food are also low FODMAP foods which could account for the symptoms people are having and relieving with a gluten free diet.

So a low FODMAP diet might be helpful instead of a gluten free diet. Below are a few links to help you get started if you think this might be for you.


Dr. Sue Shepherd 

Monash University

Stanford University Medical Clinic


2 thoughts on “The Gluten Nocebo Effect

  1. This was because, as those with gluten sensitivities
    know, gluten will cause damage to the small intestine, damaging the
    villi, which aid in food digestion. So the best advice
    is to stick with these non-grain based vodkas that are readily available these days.
    Decades ago, these foods would’ve been impossible for celiac disease sufferers to consume, unless they wanted to eat bread that tasted
    like cardboard and was as dense as a rock.

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