Exaggerations and Eucharistic Miracles

Two new forensic science papers raise concerns about Eucharistic miracle investigations. The main author, Dr. Kelly Kearse, is a faithful Catholic, Eucharistic minister for over 20 years, and science teacher at Knoxville Catholic High School in Tennessee. Kearse is also an immunologist who trained at Johns Hopkins, worked as a principal investigator at the NIH’s cancer and immunology branch, and served as editor for a Methods in Molecular Biology textbook.

Before summarizing his concerns, I want to make it clear that his purpose is not to disprove miracles and not to question the Real Presence of Christ in the Eucharist. Quite the opposite! The present concerns address exaggerations and how to correct them. Kearse points out important natural explanations that were never addressed. Until those are ruled out as causes, it is premature to claim a miracle. Kearse also provides analytical protocols that would decisively show whether the blood and cardiac tissue samples all originate from a single source, a key point in the validation of Eucharistic miracles that has never been addressed.

The first paper, “The relics of Jesus and Eucharistic miracles: scientific analysis of shared AB blood type,” was published in the Journal of Forensic Science, Medicine and Pathology. 

Five samples test positive for type AB blood, the rarest of blood types at about 5 percent of the global human population. Two are Eucharistic miracle cases, one from Lanciano, Italy (c. 750) and the other from Tixtla, Mexico (2016). According to tradition, in Lanciano the bread turned into flesh and the wine turned into blood. Both species underwent scientific analysis in the 1970s by Professor Odoardo Linoli, who reported the blood as AB type. In Tixtla, a nun noticed a reddish substance on a Host while distributing Communion; it, too, tested as type AB. The other AB results are from cloths believed to have touched Jesus at the crucifixion (the relics): the Shroud of Turin (a burial garment), the Tunic of Argenteuil (a seamless robe), and the Sudarium of Oviedo (a face cloth). 

It seems remarkable that all five test for the same, rare blood type. But there is a problem: the A and B antigens are not unique to humans. Since the 1960s, biologists have known that bacteria cells also have A and B antigens on their surfaces. Hence, if a sample is contaminated with bacteria, even if it contains no blood at all, it could still show a type AB blood result in this test. 

Yet, without anyone ever checking for bacteria as the explanation, the claim about the blood type is often repeated as miraculous. In his 2021 book, A Cardiologist Examines Jesus, Dr. Franco Serafini calculates the probability that all five samples would produce an AB result, given their rarity, to be one in 3.2 million. A 2023 article at Catholic Answers Magazine goes so far as to claim that this “statistical impossibility” is a mathematical proof for the Real Presence, proof that God is real, and proof that “our Lord has AB blood.” A 2024 article at EWTN calls type AB “the Divine Blood Type as revealed by Eucharistic miracles.” 

The investigators knew the samples were dirty, handled by multiple people, and contaminated with microorganisms. Dr. Linoli reported residuals of small dead insects and larvae on the Lanciano samples fifty years ago. The Shroud blood fibers were found to be contaminated with bacteria and fungi. The Tixtla sample was handled by multiple people over the seven years it took to investigate. Kearse maintains that “it is reasonable to propose that shared AB antigens from bacteria could readily explain the observed shared blood type.” 

Kearse describes both genetic and protein tests that can detect other antigens and the genes responsible for them, providing not only information about the source of the AB antigens (human or otherwise) but also whether the samples are genetically identical. If the samples truly contain blood from a single source—that is, Jesus—then the DNA would match for all samples. These tests are routine now. To even begin to make the claim that the AB results are a “Divine Blood Type” or a “statistical impossibility,” these tests would need to be done.  If the samples truly contain blood from a single source—that is, Jesus—then the DNA would match for all samples. To even begin to make the claim that the AB results are a “Divine Blood Type,” these tests would need to be done. Tweet This

The second paper, “Scientific Analysis of Eucharistic Miracles: Importance of a Standardization in Evaluation,” was published in the Journal of Forensic Science and Research. 

In multiple Eucharistic miracle cases, parishioners found consecrated Hosts in improper locations, too dirty to consume. According to norms, the procedure in such situations is to place the Host in water, store it in the Tabernacle until it dissolves, and then discard it in the sacrarium, a sink that goes straight to the ground and bypasses the sewer. 

In Buenos Aires, Argentina, in the 1990s, a Host was found in a candleholder near the back of a church. After eleven days in water, a reddish substance appeared on it. In Sokółka, Poland, in 2008, a Host was found on the steps of the altar. A week later, it was undissolved and covered by a red substance. In Legnica, Poland, in 2013, a consecrated Host fell to the ground and after storage in water displayed a crescent-shaped portion turning red. 

Kearse devised, for the first time ever, a set of control experiments. He obtained unconsecrated communion wafers and processed them according to the same conditions described above. He left them in a dusty, dark corner for several days and then stored them in water at ambient temperature and humidity for 7-10 days. Approximately 15 percent of the control wafers formed a gelatinous red substance on the surface, like the photos from the Eucharistic miracle reports. 

Microscopy, fluorescence, and molecular biology techniques showed the reddish substance to be fungus and bacteria. Again, this is a natural explanation that was not checked but easily could be. Kearse presents a variety of tests showing that blood can easily be distinguished from microorganisms. As before, genetic testing would ultimately confirm what the red substances are and whether they have a single origin. 

Another concern regards the claim of divine DNA. Only the Buenos Aires and the Tixtla samples underwent a forensic DNA test, known as an amplified PCR (polymerase chain reaction) test. The Buenos Aires study indicated that “a very low concentration of human DNA was recovered” and that the sample contained a good amount of DNA from a “non-human origin.” For the Tixtla sample, no human DNA could be detected at all. 

A “very low concentration of human DNA” is indicative of handling contamination. In forensic DNA tests, trace amounts of DNA from humans who touch a sample can be unintentionally amplified, and reports say the Hosts were touched by several people. 

As for DNA of “non-human origin,” the forensic lab reports simply show an “N.R.” (no result). Yet, instead of reporting the straightforward result that no human DNA was detected, the investigators went the other way. They said that human DNA was present but defies detection because it is of divine origin, explaining that Jesus’ DNA would only have maternal DNA and no paternal DNA from a biological father. If this is the standard for testing miracles, then anyone can conclude anything.

Kearse ran the same DNA tests on his controls and found that non-human DNA does, in fact, show up in the form of plant DNA from wheat in the wafer. He found that bacterial and fungal DNA were abundant as well, which would show up as non-human DNA. These natural explanations must be checked before claims of divine DNA can be taken seriously. 

Recently, Edward Pentin reported on the worldwide Vatican International Exhibition began by Blessed Carlo Acutis, the teenager who traveled the world to catalog 160 Eucharistic miracle investigations and died at the age of fifteen from leukemia. These stories are published by the Real Presence Eucharistic Education and Adoration Association in their book and exhibit The Eucharistic Miracles of the World. Pentin notes that the exhibit has been shown in thousands of parishes and at more than 100 universities globally. The book and posters repeat all the exaggerations mentioned here. 

Hopefully, a new team will be formed to coordinate genetic tests on all available Eucharistic miracle samples and implement Kearse’s recommendations for a standard protocol. I asked him how he thought Catholics would take this news. He said: 

Transformation of communion bread into literal human tissue and blood is an extraordinary and historic event. True faith should welcome evaluation at the scientific level, in as detailed and transparent of a manner as possible, to establish the validity of such findings so that they may be shared unequivocally with the world.

The results may show that all the samples are from the same human body, which we could reasonably assume to be that of Jesus Christ! Or they may show that none of these cases are miraculous after all. As disappointing as that would be, Catholics are truth-seekers who believe in the testimony of Christ. It would be tragic indeed, worse than big-haired charlatans faking miracle cures on television, for Catholics to try to convince the world of the Real Presence of Christ in the Eucharist with unsubstantiated scientific claims about bleeding hosts and divine DNA. Thanks to Kearse, there is a way to obtain better information. Starting those tests yesterday would not be soon enough.