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. For each specific product tested, three samples (e.g., 3 packages of noodles, 3 boxes of cereal, 3 bags of chips) are purchased. Beginning in June 2013 one sample of each specific product will be purchased (but two different products will be tested each week).
3. Samples are sent unopened to Bia Diagnostics, an independent food testing lab in Burlington, Vermont.
4. Samples are tested 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 three samples instead of one gives us a better "picture" of the gluten content of the product. Regardless, this is a snapshot of the gluten content of a particular product at one point in time. There is no way of knowing without testing many more samples whether the results of the three samples tested are representative of the gluten content of this product as a whole.

Please note that starting in June 2013 we will be testing two different products weekly (one sample of each product). One product will be labeled gluten-free; the other product will not be labeled gluten-free but appear to be gluten-free based on ingredients.

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. 


Initially we tested four new products monthly. In June 2013 we started testing at least eight new products monthly.

Gluten Free Watchdog, LLC conducts follow-up testing of labeled gluten-free products that test greater than or equal to 20 parts per million of gluten within one year of the original test date. Manufacturers can request that retesting occur sooner than one year (please see the manufacturer page). If a product continues to test at or above 20 parts per million of gluten a complaint will be filed with the Food and Drug Administration's Consumer Complaint Coordinator.
Foods NOT labeled gluten-free are not retested as the manufacturer is making no warranties regarding the gluten-free status of their product.

Any product labeled gluten free may be selected for testing. Products are randomly selected from store shelves and also may be mail ordered. Consumers and dietitians also may request testing of a certain product via our contact form. A request for testing does not automatically mean that a product will be tested.

Starting in June 2013, products that appear to be free of gluten containing ingredients but are not labeled gluten-free also may be selected for testing following the same protocol as above.

No. All products tested are purchased by Gluten Free Watchdog, LLC at retail outlets.