By Dante Moroni

In late 2013, Biesiekierski et al. published a paper in the American Journal of Gastroenterology that was the first to provide evidence that FODMAPs (Fermentable, Poorly Absorbed, Short-Chain Carbohydrates) may be responsible for adverse symptoms of NCGS patients, instead of gluten.¹ Since then, there have been several studies conducted that investigated this observation. In this blog post I would like to review one of these studies, Skodje et al. 2018², and provide my own interpretation of the results along with critiques in studies design.

Let’s start with off with dosage and think about how that may have affected the results. In this study NCGS patients where given a muesli/granola bar that was either formulated with fructans, gluten, or neither. The FODMAP bar was spiked with 2.1g of fructans and the gluten bar with 5.7g of gluten. I don’t think 2.1g of fructans can be fairly compared to 5.7g gluten. My reasoning is as follows. Since 100g (~2.6 slices) of bread contains about 1.3g fructans³, and a slice of bread contains about 4g of gluten, you would actually want to dose with 16.8g of gluten for a reasonable comparison. 5.7g of gluten is nowhere near this amount and could explain the lack of increased symptoms.

Next let’s talk about statistics and data interpretation. Just by looking at the graphs comparing IBS scores to testing arms, we can see a large variation in patient outcomes. However, the authors were able to work their statistical circus tricks in order to draw a conclusion from the data and still only got statistical significance for bloating (p=0.004) and just barely reached significance for overall IBS symptoms (p=0.04). In my opinion there is way too much variation patient to patient and I don’t really see a significant difference between the groups. I’ve provided the overall IBS symptom graph and you can make your own judgement.

Part A of Figure 2 from the paper.

I believe the way the data was presented to the reader was silly not a good representation of what really happened in the study. They compared IBS scores to how much it differed from the placebo group. When you look at the IBS scores (0-100) from a bigger picture point of view, instead of a micro comparison you will see what I mean.

In summary, I do not think this study should lend much if any information to the hypothesis that FODMAPs are what drive NCGS and not gluten. Considering some recent media headlines that outright blame FODMAPs and quote studies like this one, you may understand my motivation for writing articles like this.

References

1. Biesiekierski JR, Peters SL, Newnham ED, Rosella O, Muir JG, Gibson PR. No Effects of Gluten in Patients with Self-Reported Non-Celiac Gluten Sensitivity After Dietary Reduction of Fermentable, Poorly Absorbed, Short-Chain Carbohydrates. Gastroenterology. 2013;145:320-328.
2. Skodje GI, Sarna VK, Minelle IH, Rolfsen KL, Muir JG, Gibson PR, Veierod MB, Henriksen C, Lundin KEA. Fructan, Rather Than Gluten, Induces Symptoms in Patients with Self-Reported Non-Celiac Gluten Sensitivity. Gastroenterology. 2018;154:529-539.
3. Whelan K, Abrahamsohn O, David GJP, Staudacher H, Irving P, Lomer MCE, Ellis PR. Fructan Content of Commonly Consumed Wheat, Rye, and Gluten-Free Breads. International Journal of Food Sciences and Nutrition. 2011;62:498-503.