The unleavened bread used during Holy Communion in Roman Catholic Masses must contain at least some gluten, the Vatican said in a recent statement.

In a June 15 directive, which circulated over the weekend following a report from Vatican Radio, the church reaffirmed policies regarding the host, or sacramental bread, and wine used during the celebration of the Holy Eucharist.

Quoting from a 2003 letter to bishops from the Congregation for the Doctrine of the Faith, Cardinal Robert Sarah wrote, “Hosts that are completely gluten-free are invalid matter for the celebration of the Eucharist.”

Low-gluten hosts are valid, he said, but they must contain “a sufficient amount of gluten to obtain the confection of bread without the addition of foreign materials and without the use of procedures that would alter the nature of bread.”

During the Eucharist ceremony, Roman Catholics consume bread and wine as the body and blood of Jesus Christ.

Gluten, a protein in wheat and other grains, has come under scrutiny in recent years as awareness about celiac disease and other gluten-related sensitivities has increased. Celiac disease, an autoimmune disorder that affects digestion in the small intestine, can cause symptoms ranging from stomach pain to infertility. The condition affects roughly 3 million Americans, or 1 percent of the population, according to The University of Chicago’s Celiac Disease Center.

The Vatican’s directive said the church felt compelled to clarify its policy due to the ease with which congregations can purchase Communion bread in today’s world. The Vatican does not approve of gluten-free substitutes that include ingredients that mimic the natural effects of gluten.

“Until recently, it was certain religious communities who took care of baking the bread and making the wine for the celebration of the eucharist,” the letter stated. “Today, however, these materials are also sold in supermarkets and other stores, and even over the internet.”

The directive also said that Eucharist materials could be made with genetically modified organisms but called it “a grave abuse” to use ingredients such as fruit, sugar or honey in Communion bread. 

In addition to the rules surrounding hosts, the church approved the use of mustum, a non-alcoholic grape juice that has been partially fermented, as a substitute for Communion wine.

The U.S. Conference of Catholic Bishops said anyone who cannot ingest even a small amount of gluten may receive a “wine only” Communion.

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