[Question:]{.underline} Would a person suffering from Celiac disease be protected by transubstantiation from being harmed by gluten in the host?
[Answer:]{.underline} The argument that the accidental qualities of bread cannot harm the intestine of one who suffers from Celiac disease (non-tolerance of gluten in wheat bread) is false. It is of course true that the substance of the bread does not remain after the consecration of the sacred species. However, all the accidents remain, which includes not just the exterior appearance, but everything that is subject to the senses and that science can investigate, including the chemical composition. The chemical effects of the gluten on the intestinal wall will consequently still remain, just as much as the appearance and texture of bread, for they are just as accidental to the real nature of what is there as the appearance and texture. Here lies the miracle and the mystery of the Blessed Eucharist. It would be a miracle if the accidental qualities of gluten were not to harm the intestine. Although such miracles can happen, we cannot depend up on such an extraordinary intervention of Almighty God.
Consequently, a person who suffers from Celiac disease needs to ask the priest to give him a very small portion of the host, if his sensitivity is not too acute. However, if his intolerance of gluten is such that he cannot tolerate even the smallest quantity of a gluten containing substance, then he has no alternative than to request a special indult to receive Holy Communion under the species of wine, from a special chalice. It is never permissible to manufacture the host out of rice or a non-wheaten material that does not contain gluten. Such hosts are not valid matter for the Holy Eucharist. Likewise, hosts manufactured out of wheat from which all the gluten has been removed (now available), must be considered doubtful matter, since gluten is a protein, necessary for the make up of wheaten flour. It is not permissible to use such matter to make hosts, since we must follow the safest possible path with respect to the sacraments, nor is it permissible to expose them even to the small possibility of invalidity due to defect of matter.
Answered by Father Peter Scott, SSPX.