The Vatican has ruled that bread used to celebrate the Eucharist during Roman Catholic Mass must not be gluten-free – although it may be made from genetically modified organisms.
In a letter to bishops, Cardinal Robert Sarah said the bread can be low-gluten.
However, the cardinal said there must be enough protein in the wheat to make it without additives.
The new Vatican rules are needed because the bread is now sold in supermarkets and on the internet, the cardinal said.
Roman Catholics believe bread and wine served at the Eucharist are converted into the body and blood of Christ through a process known as transubstantiation.
Cardinal Robert Sarah of the Vatican’s Congregation for Divine Worship and the Discipline of the Sacraments said the wine used must also be “natural, from the fruit of the grape, pure and incorrupt, not mixed with other substances”.
The Vatican letter said that the ruling was issued at the request of Pope Francis.
There are about 1.2 billion Roman Catholics around the world.