Careful testing of beers labeled "gluten-free" and "low-gluten" revealed that several contained the barley protein hordein, which causes a similar reaction to gluten in people with celiac disease and non-celiac gluten sensitivity, a new study shows.
The study, published last week in the open-access medical journal PLOS One, compared hordein protein levels in 60 different beers, using two different types of testing. It found low but significant levels of hordein in two gluten-free beers, and higher levels in two so-called "low-gluten" beers.
The research comes from the same Australian team that looked previously at "low-gluten" beers, which apparently are relatively common Down Under but aren't found in the U.S. and Canada. Each beer -- including eight gluten-free beers and two "low-gluten" beers -- underwent laboratory analysis with two different tests.
The good news: six out of eight of the gluten-free-labeled beers really were gluten-free, at least to the very low limits of these tests. Interestingly, this included both gluten-free beers made from "de-glutened" barley (no products were identified by name).
Two of the eight gluten-free beers contained hordein proteins at between 1% and 4% of the average for all the beers (not a huge amount, certainly, but probably enough to make some of us react).
The "low-gluten" beers, meanwhile, contained hordein at levels near the average for all beers ... including those beers not marketed as gluten-free (one, in fact, contained barley protein at a level 40% higher than the average for all beers).
Several conventional barley beers also contained undeclared wheat proteins, a particular problem for someone with a wheat allergy (those of us who can't tolerate gluten wouldn't choose one of those, obviously).
The bottom line? Testing shows that the majority of beers marketed as "gluten-free" are in fact gluten-free to levels below 1 part per million (for reference, less than 20 parts per million is accepted as the "gluten-free" standard in the U.S. and Canada).
The researchers also determined that testing the beers with what's called "multiple reaction monitoring mass spectrometry," or MRM-MS for short, detected barley protein in beers where the more commonly used sandwich ELISA test came up with a false negative (the sandwich ELISA works well for the wheat protein gluten but is known to underestimate the barley protein hordein).
The researchers recommended using the MRM-MS test for gluten-free beer, specifically because it can detect hordein far more effectively than the sandwich ELISA test.
I also should note that several of the non-gluten-free beers also contained very low levels of gluten and/or hordein -- perhaps that explains why some celiacs and gluten-sensitive people report they can drink certain "regular" beers without reacting.
For my list of safe beers, see: Gluten-Free Beer
Photo © Getty Images/Jack Andersen