The Eucharistic Miracle of Lanciano

The tradition holds that around the 8th century, a monk at Lanciano who doubted the Real Presence saw the host and wine of the Mass turn visibly to flesh and blood. The relics — a piece of "flesh" and several pellets of "blood" — have been preserved and venerated at the church there ever since.

The 1971 analysis

In 1970–71, Odoardo Linoli, a professor of anatomy and histology, was permitted to examine the relics. He reported that the flesh was striated muscle of the myocardium (heart wall), that the blood was human, and that both shared blood type AB. The findings were published and have been widely cited.

The provenance problem

The result is the kind of thing that should move a careful reader — and then the chain of custody collapses it. There is no continuous, documented record tying the object in the reliquary today to anything that happened in the 8th century. Over a thousand years of veneration, the relic could have been substituted, restored, or replaced at any number of points. The 1971 study, while performed by a credentialed examiner, has not been followed by the kind of independent, modern, multi-laboratory work — DNA, controlled dating — that an extraordinary claim of this sort demands.

Where this lands

What we have is a striking analytical result attached to an unverifiable object. The tissue may well be human heart muscle. That tells us almost nothing about whether it appeared miraculously thirteen centuries ago. Until the relic is subjected to controlled modern testing — and the provenance gap is, by its nature, unbridgeable — this stays a low-confidence case despite its fame.