A tale by Herman of Bologna in the Viaticum narrationum (ca. 1280–1290) describes the rather comical story of how a Jew of Cologne, having received communion, kept the host in his mouth; when he removed it, he discovered that it had turned into a tiny child. When he put it back in his mouth, it had become so hard he could not chew it or swallow it, and eventually, admitting the miracle, he was converted. This was in fact the first literary tale in which a Jew ingested the Eucharist. Many versions of this tale continued to be circulated in the later Middle Ages.¹⁷²

(Emphasis added. Source.)