.- Vatican officials have said there are no plans to discuss changing the matter of the Eucharist during an upcoming synod for the pan-Amazonian region of South America.

The possibility of changing the kind of bread allowed to be used in the celebration of the Eucharist does “not appear in the Preparatory Document for the Special Assembly next October and therefore is not a subject of the next Synod,” Bishop Fabio Fabene, Undersecretary of the General Secretariat of the Synod of Bishops, told CNA Friday.

The clarification comes after a Brazilian Jesuit theologian said last month that the October synod on the Amazon could consider the substitution of wheat bread in the eucharistic species with a host made from yuca – a root plant common in the Amazon.

The exclusive use of bread made from wheat and wine for celebrating Mass is explicitly regulated by the Church, with any other material defined as invalid matter for the sacrament.

Fr. Francisco Taborda, SJ, said Feb. 28 that a fundamental shift in the matter of the Eucharist was a likely topic to be addressed during the special session of the Synod of Bishops for the Pan-Amazonian region in October.

Speaking to Crux, Taborda suggested that because of the humidity in the Amazon at different times of the year, wheat bread sometimes becomes overly moist - something he suggested could justify a radical departure in sacramental teaching and disciple.

If bread turns too moist, “it’s not bread, and if it’s not bread, it’s not the Eucharist,” he said.

“In the Amazon, bread is made out of yuca.”

Taborda said that the decision to substitute the essential matter of Eucharistic consecration should be left to local bishops. Fabene told CNA that “the changing of the Eucharistic matter is the competence of the Congregation for the Doctrine of the Faith.”

The 80 year-old theologian is an emeritus professor of theology at the Jesuit Faculty of Philosophy and Theology (FAJE) in Belo Horizonte, Brazil, where he taught for many years. He has written several books, including on the theology of the sacraments.

Taborda spoke to Crux while attending a seminar entitled "Toward the Special Synod for the Amazon: Regional and universal dimensions," and held in Rome Feb. 25-27.

While the study session was organized by the General Secretariat of the Synod of Bishops, a Synod spokesman told CNA that Taborda’s statements “are exclusively personal,” and do not represent official plans.

The teaching of the Church on the essential matter for the consecration of the Eucharist is closely regulated. Canon 924 §2 of the Code of Canon Law states that the bread “must be only wheat.” Similarly, the wine used must be natural and made from grapes and mixed only with water.

Fr. Mark Morozowich is the Dean of the School of Theology and Religious Studies at the Catholic University of America, an ecclesiastical faculty with special authority from the Vatican to teach theology.

Morozowich explained to CNA the principles that govern “enculturation,” or deference to local circumstances, within the Mass.

“The Church has always enculturated the liturgy,” he said. “This is something we’ve done through the centuries in every single place from the very beginning.”

Starting with the first ministry of the apostles, he said, “the Church lived Jesus Christ, proclaimed his cross, death, and resurrection. The Church proclaimed Jesus Christ being present body and soul in the elements of the Eucharist.”

He said that there have been, and continue to be, some regional differences in the matter used in the celebration of the Eucharist, but those differences are limited by the Church’s doctrinal teaching.

“Classically, we can look at the very clear acceptance of the Byzantine rite having a leavened bread for its Eucharist, whereas the Roman Church has an unleavened bread for its Eucharist.”

“Both are different but yet both are valid matter according to their own ritual tradition,” Morozowich said. “This is something that has been going on for two thousand years.”

“Some people talk about the use of something else besides wheat flour or the use of something besides wine in the Eucharist; one important part of this is certainly about [remembering] what we are expressing in this prayer, but there’s a continuity to the sacrifice of Christ when he was on this Earth. That basic principle needs to be reflected in all these discussions.”

The Mass is not, Morozowich said, about enacting an exact historical recreation of the last supper, “but at the same time the Church has said there are some core elements of this reality of the presence of this way the [Christian] community has celebrated throughout its life time.”

“The Church needs to be very cautious with what are the latest ‘fads’ if you will,” he said. “The Church is very concerned to present the culture and the prayers in a way that is telling and faithful to the way they have been lived through the centuries.”

Even within the differences between the Latin and Byzantine rites, he said, there is an essential continuity of Eucharistic matter.

“Leavened or unleavened, the Church has always used wheat bread. Whether it is mixed with hot or cold water, or mixed once or twice, the Church has always used wine,” Morozowich said.

“These are essential, so that as the believer celebrates the Eucharistic and reflects on the institution of that Eucharist, they have a sense of a transcending of time and a sense of the true presence that is mediated through these specific elements.”