I’m going to give you the conclusion up front. Your gluten free diet may not really be gluten free, but a very low gluten diet.

In late 2019, the results of the DOGGIE BAG study were published. DOGGIE BAG stands for Determination of Gluten Grams Ingested and Excreted by Adults on a Gluten free diet. They took 18 patients on a gluten free diet for at least 24 months who were primarily asymptomatic. The patients provided 25% of all of the food, including sauces, they consumed for 7 days to scientists. The patients also provided urine and stool samples for gluten testing.

They found that gluten is creeping into even the most strict gluten free diet. The scientists found that 8% (25 samples out of 313) of the food samples collected indicated the food contained gluten. Of the 25 samples that had detectable gluten, the median gluten concentration was 11ppm. Ten samples (40%) contained greater than 20ppm and five (20%) samples had greater than 200ppm.

I want to say that these numbers are shocking. That’s a lot of gluten in a few of these samples. However, only a very, very small percentage of the food eaten contained a significant amount of gluten. We don’t have details of what these people ate. The scientists did not test naturally gluten free foods like fruits, vegetables, and wine. Therefore, the number of foods containing detectable gluten could be lower.

After eating all of these foods, the scientists collected urine and stool samples. They detected gluten peptides in 6% of urine samples from eight participants and 11% of stood samples from five participants. Again, gluten was detected in a very small number of excretory fluids. As a side note, if you consume gluten it will be processed by the body and excreted. This is a normal function and even those without celiac will excrete gluten.

Now, after this they were also testing TTG IGA and biopsies. The amount of gluten consumed had no correlation with blood tests or biopsies. For example, two study participants had no food that tested positive for gluten. They also had no gluten in their stool or urine. Yet, one had improved biopsy results. The other did not. At the same time, two people who consumed foods containing more than 100ppm of gluten had improvement on their biopsies. So, who the hell knows.

We confirmed some things we already knew from this study. Most people attempting to avoid gluten still consume gluten on a regular basis. There are no really good tests to decide compliance with the diet.

Celiac damages the gut. It will continue to do so whether gluten is removed or not. The real question is, what causes this continued damage and how do we fix it. I think this is the most important question because simply eliminating gluten isn’t enough. And even when someone is 100% compliant on the gluten free diet doesn’t guarantee proper healing. This celiac problem has more layers that we don’t really understand just yet.

Link to study https://www.gastrojournal.org/article/S0016-5085(19)41945-8/fulltext