Test result from Moms Across America for Trader Joe’s Gluten Free Almost Everything Bagels Possible False Positive

Gluten Free Watchdog tested Trader Joe’s Almost Everything Bagels due to consumer concerns over the results of testing commissioned by the group Moms Across America.

This is a complex test report summary. Please bear with us as we try to explain the discrepancy between the Moms Across America test results and Gluten Free Watchdog test results.

Bottom line: The test result from Moms Across America for Trader Joe’s Gluten-Free Almost Everything Bagels may be a false positive, especially if the lab did not use extra protein to prevent non-specific binding (please see explanation below). As a reminder, the lab used by MAA tested the bagels with the G12 ELISA from Romer Labs. The bagels reportedly tested at 269.8 parts per million of gluten. Final testing done through Gluten Free Watchdog using the R5 ELISA and the G12 ELISA was below the lower limit of quantification (< 5 parts per million of gluten or < 4 parts per million of gluten depending on the assay used).

Testing done at Bia Diagnostics for Gluten Free Watchdog:

Three bags of bagels with three different best by dates were tested. The bagels were tested using two different assays–the R5 ELISA and the G12 ELISA. Bagels were tested with and without a milk additive (see explanation below).

All eight food portions tested with the R5 ELISA tested < 5 parts per million of gluten (below the limit of quantification).

The food portions tested with the G12 ELISA without a milk additive tested with quantifiable gluten (>/= 4 ppm gluten). The food portions tested with a milk additive tested < 4 parts per million of gluten (below the limit of quantification).

Why the discrepancy in the results?

This section is important to read and understand.

Enzyme-linked immunosorbent assays (ELISAs) like the R5 and G12 are based on what is called an antigen-antibody reaction. If gluten is present in the food samples that are being tested, it will bind to the antibodies in the R5 and G12. Sometimes what is called non-specific binding occurs—meaning something other than gluten binds to the antibodies. This may cause false positive results. To help prevent non-specific binding, extra protein in the form of milk protein or fish gelatin may be included in the testing process.

When the R5 ELISA was used to test the bagels for gluten, the results were the same regardless of the use of a milk additive. However, when the G12 ELISA was used, the use of a milk additive appears to have prevented non-specific binding. This means that the milk additive appears to have prevented false positive results.

Gluten Free Watchdog has been in touch with Romer Labs (manufacturer of the G12 ELISA) and R-Biopharm (manufacturer of the R5 ELISA). They both offered suggestions on possible ingredients in the bagels that could be causing the non-specific binding. We are in the process of having these ingredients tested at Bia Diagnostics. To date, results suggest that brown rice flour and sorghum flour may cause non-specific binding when the G12 ELISA without a milk additive is used to test these ingredients for gluten.

Next steps:

Gluten Free Watchdog will not be testing every product tested by Moms Across America and found to contain quantifiable gluten. We recommend that the lab used by MAA retest products from their retained samples, using extra protein to prevent non-specific binding.

Something for all of us to keep in mind:

Testing food for gluten is complicated. It is often not straight forward. Results must be scrutinized. When test results don’t make sense (and everyone involved in testing food for gluten has been there), there is likely a reason. The key is to try to figure it out—why are there discrepancies in test results? Sometimes we never figure it out but sometimes we do. And this is how we learn.

Addendum August 1, 2024: Additional information for those who may be interested in testing protocols… Gluten Free Watchdog commissioned two rounds of bagel testing from Bia Diagnostics. In the first round, a milk additive was included when testing the bagels using the R5 ELISA. This was done because the instructions call for the addition of milk additive when testing tannin and polyphenol containing food samples. A milk additive was not included when testing the bagels using the G12 ELISA. According to Bia Diagnostics, the kit instructions for the G12 call for fish gelatin (extra protein) when testing chocolate containing samples. The bagels do not contain chocolate. In round two of testing, we decided to switch the protocol. We did not use milk additive when testing using the R5. We did use milk additive when testing using the G12. We then had to put on our thinking caps to figure out what might be causing the discrepancy in results between the R5 and G12 when following the kit instructions for both assays. This involved reaching out to both R-Biopharm and Romer Labs for their thoughts regarding non specific binding when testing using the G12 and what ingredient(s) might be causing it.