Gluten is a protein fraction from certain grains, including barley and wheat, which causes coeliac disease in a small percentage of the population.
Although barley contains gluten, much of it is broken down and eliminated during the production of beer. However, traces can remain, which may trigger a reaction in sensitive individuals. Additionally, the levels of gluten in beer vary greatly depending on the materials used and the production process. Since the sensitivity to gluten also varies considerably, some beers may be safe for some coeliac patients to drink, but not all in either case. In the EU, beers with no more than 20 mg/kg of gluten may be labelled as “gluten-free”.
Both Heineken® Original and Heineken® 0.0 are not gluten-free and have levels of gluten just over 20 mg/kg, this is just over 0.002%.