Chemistry is the core of our product, Nima. Every time someone tests food, she is basically basically performing a miniature chemistry experiment (science is so cool!). Reliable results are critical to us. We know that people are going to use our product to make informed decisions about what to eat after looking at the results. Like all good scientists, our chemistry team is constantly testing things and gathering data to help achieve reliability and accuracy when testing food for gluten.

As part of the validation for chemistry, over the past year we’ve been looking at places in San Francisco with reports of gluten free foods are not so free of contamination. To qualify as gluten-free, the US FDA has determined the measurement of less 20 parts per million (ppm). We recognize this can be a struggle for restaurants – particularly with regards to cross contamination. Indeed, in the wake of this announcement, many restaurants have changed menus to indicate that while an item contains gluten free ingredients, they can’t control for cross-contamination.

So, what did we do?

In a study last year we gathered samples from five restaurants where consumers had indicated in various online reviews that the food had made them sick. Our research shows people with gluten allergies get sick at least one in every three times they eat outside the home. Dishes that were specifically mentioned by testers in specific restaurant reviews – everything from donuts to french fries to lamb – were the core of our research.

We wanted to understand what the average person might test. Working with an outside partner, we took three different samples of the each food. The smallest sample across the 27 samples (9 foods, 3 weights each) was .138 grams and the largest 2.983. The variance can be explained by the differing densities of the foods tested. The heaviest was a lamb and the lightest a dosa. Why do we care? We know that when people sample food, they may not all take the same sample size. We also know the chemistry has to work for all types of food. So by testing, as we did in this small study, we can begin to understand how this will work in the real world. (Trust us, this is just one of a series of ongoing tests.)

Each sample was then tested using Sandwich ELISA. ELISA is an acronym – enzyme-linked immunosorbent assay. As the name suggests, sandwich ELISA basically captures the amount of gluten between two antibodies. Antibodies are proteins that specifically recognize molecules that celiac or gluten intolerant populations respond to, including gliadin in wheat, hordein in barley and secalin in rye.

The results showed that every sample tested came under 20 ppm – so all met the definition for gluten free. However, allergic consumers may react at lower levels — as we found in using our CEO, Shireen, as a guinea pig. Two of the donuts (supposedly gluten-free) tested did have trace levels of gluten – one flavor at 10.1 and the other at 9.8 ppm. Shireen was happily eating them one minute and unwell before we even had the results of the test back. Everything else was below 5 ppm, so was happily shared with our gluten free folks on the team.

gluten test results for restaurants

This does show that for those with gluten allergies and Celiac that it cross contamination is very real. It can also have unfortunate side effects, as Shireen found out after her mini donut binge. We’ll continue to conduct these tests and will share more results in the future!