Over the weekend Pope Francis issued a letter saying that Catholics can't use gluten-free communion wafers to participate in Holy Communion.
Only unleavened wheat bread can be used.
For those Catholics with Celiac disease and other gluten allergies, low-gluten substitutes are allowed, as long as there is enough gluten to still make it "wheat bread."
Sorry you gluten-allergy-having people, that's the requirement for the sacrament.
The Church's law states:
"Bread made from another substance [...] does not constitute valid matter for confecting the Sacrifice and the Eucharistic Sacrament.”
The Pope's letter also reminds Bishops that wine must be "fruit of the grape" and not mixed with anything else.