Whatever one takes this to mean, it is clear enough that literal flesh and blood are not in view, otherwise the Jerusalem council would not have advised the believers there to “abstain from blood” (Acts 15:28-29). It is worth noting that not even Roman Catholics interpret the surrounding context literally. Throughout the chapter, Jesus identifies himself as the bread of life five different times. In spite of this, however, the doctrine of transubstantiation holds that the elements of the Eucharist are not actually bread and wine (they are said merely to have the incidental characteristics that accompany bread and wine, though their substance is identical to Jesus himself). Thus, no one interprets the passage in an overly literal fashion, and there is no need to do so.
You may also be interested in Cannibalism in the Bible