The wafers used to symbolize the body of Christ, referred to as “hosts,” must be “unleavened, pure of wheat.” The Vatican’s letter goes on to rule gluten-free hosts “invalid,” but “low-gluten hosts” perfectly acceptable.
This isn’t a new development that’s a response to the popular health craze/awareness of gluten intolerance. The letter points out that these guidelines were put in place in March of 2004 in the Instruction Redemptionis Sacramentum. The Vatican was reacting in part to the appearance of gluten-free wafers available for commercial purpose, according to reports.
The letter also outlines rules for communion wine and host production, insisting that producers must know that they’re making these items for the Church’s use and ingredients must be pure with no other factors incorporated.