This statement is being distributed by Sapporo Breweries:
"A representative from Sapporo Breweries, Ltd./Tokyo has advised that Sapporo beer does contain barley. However, after the barley is boiled, the gluten is filtered out along with the barley skins. The representative assured me that although the barley itself does contain gluten, their brewing process effectively removes all the gluten from their beer."
The reason that this doesnt make sense for celiac patients has to do with the digestion of the barley hordeins, the proteins that are similar to wheat gliadins in barley. During the malting and fermentation processes, the barley hordeins are broken down into smaller pieces called peptides. It is true that no intact hordein proteins can generally be found in beer. However, the smaller pieces of these proteins resulting from enzymatic digestion are often quite water soluble so that they remain in the beer throughout the complete processing to the final product. (Remember that beer is not a distilled product as are whiskey or vodka. Filtration of the beer will not remove these small water-soluble hordein polypeptides.) A barley hordein might have a polypeptide chain including 300 amino acids in its sequence, yet it is reasonably well established by experiments that polypeptides with as few as 13 amino acid residues in the chain can still retain toxicity for celiac patients. These small pieces of the original proteins can (and do) have very different properties from the original larger proteins. In the strict sense, Sapporo is correct that there are no more intact hordeins in their beer. What they cannot claim is that there are no hordein peptides in the beer that might harm celiac patients.
There is some evidence from analytical methods involving antibodies prepared to gliadins that there are peptides in beer that react with these antibodies. It is not proved beyond any doubt that the peptides in beer are actually toxic to celiac patients, but it is quite possible that the peptides remaining in any barley-based or wheat-based beer, Sapporo included, are harmful to celiac patients. The amount of harmful peptides, if they are present, is likely to be small, but there is no satisfactory analytical data, in my opinion, that defines the amount exactly. So it could be in a range that would be harmful to a celiac patient drinking beer on a regular basis. My guess is, and I emphasize that I cant back this up with scientific results, that a glass of beer once every few months would not do lasting harm to the average celiac patient. By average celiac patient, I mean those who have no obvious allergic character to their disease and do not notice any immediate reaction when they ingest gluten.