Frequently Asked Questions

The most commonly asked questions about how Gluten Free Watchdog works.


1. Food products are purchased from store shelves and through mail-order.
2. Samples are sent unopened to Bia Diagnostics, an independent food testing lab in Colchester, Vermont.
3. Samples are tested at least in duplicate using the standard sandwich R5 ELISA (R7001 Ridascreen Gliadin) and extracted with the cocktail solution (Art. No. R7006, official R5 Mendez method). If needed, samples also may be tested using the competitive R5 ELISA (R7021 Ridascreen Gliadin Competitive).

At the present time the R5 ELISA (R7001 Ridascreen Gliadin) is widely regarded as the best available formally validated ELISA for assessing final food product for gluten. The R5 ELISA is one of only two commercially available ELISAs validated at the levels used for regulatory purposes and official governmental methods (the other is the Morinaga Wheat Protein ELISA). The R5 ELISA is included in the FDA’s Question and Answer page on the gluten-free labeling rule as one of the methods the agency will use for rule enforcement if testing a product becomes necessary.

Testing each sample in duplicate does two things: it helps guard against laboratory error and it helps ensure that the sample tested is homogenized. This means that any "contaminant" (in this case gluten) is well distributed within the sample. If the results of the two extractions are fairly similar a reasonable amount of confidence can be placed in the results. Some products may be more difficult to homogenize than others. 


At least eight new products are tested monthly.

Yes. If you would like a previously tested product tested, please let us know.

Products labeled gluten-free and products appearing to be free of gluten-containing ingredients (but not labeled gluten-free) may be selected for testing. Consumers and health care providers may request product testing via our contact form. A request for testing does not automatically mean that a product will be tested. Almost all products currently tested by Gluten Free Watchdog are consumer/dietitian requests.


Products tested are purchased by Gluten Free Watchdog, LLC at retail outlets. Exceptions are made when a product is very difficult to find or must be ordered in bulk.