The Brewing Process
Brewing breaks barley gluten into smaller pieces. To make gluten-removed beers, brewers add additional enzymes to break down the fragments even further. Beer companies argue the resulting protein fragments are too small to be recognized as gluten by the immune systems of people with celiac disease.
These claims are difficult to prove. Standard food safety tests measure whole gluten proteins. Once these have been broken down, no one knows absolutely what fragments remain or how toxic they may be for people with celiac disease. Although some tests can detect certain fragments, experts have not agreed on a test sensitive enough to catch all of them. For this reason, U.S. guidelines prohibit gluten-free labels on any beer made from wheat, barley
A New Way to Detect Gluten
The Gluten Intolerance Group tried a new approach: testing reactivity of beer with antibodies from human blood. The study took blood samples from 31 people with untreated celiac disease and 29 without celiac for comparison. These were used to test samples of barley, regular commercial beer, gluten-removed beer and gluten-free beer. Gluten-free beers include those made from grains other than wheat, barley and rye.
Antibodies from 11 of 31 celiac patients reacted significantly to barley. Four of the 11 also reacted to conventional beer while three reacted to gluten-removed beer. A variable response was expected, as people with celiac disease are known to react differently to different strains of wheat and barley. Meanwhile, one of the 29 control samples reacted with barley but not with any of the beers. The results show both conventional beer and gluten-removed beer can contain protein residue potentially harmful to people with celiac disease.
None of the celiac disease patients reacted to gluten-free beer.