Out of curiosity, why did you post this in “traditional Catholicism” rather than “moral theology”? I do not imagine that traditional Catholics would have a different view of this subject than any other Catholics.
I fear that you are taking Acts 15:29 out of context. It is not prohibited for Christians to consume blood today. Since you are British, you will be familiar with black pudding, your native variety of blood sausage. It is now entirely permissible for Christians to eat black pudding and other varieties of blood sausage. Why? Because the verse that you are citing is part of a summary of the conclusions reached at the Council of Jerusalem. This council addressed disputes arising between Jewish and gentile Christians in the early Church. The prohibition against consuming blood therefore pertains to the specific situation of Christians who belong to a community comprising both Jews and gentiles. It was a temporary measure intended to settle a dispute pertaining to a specific situation. The gentiles did not have to obey the whole of the Jewish law, but they were to refrain from consuming blood as this was considered particularly offensive by their Jewish brothers and sisters. Unless you belong to a congregation that includes a substantial number of Jewish converts who observe the dietary laws and feel that the consumption of blood by gentiles puts their Christian faith in jeopardy, you no longer have to obey this regulation. Therefore, this verse not only has nothing to do with blood transfusions, but does not even impose a prohibition that is binding upon Christians today.
In general, I would avoid paying too much attention to what the Jehovah’s Witnesses say. They do not belong to the mainstream of Christianity. Whereas the Church of the East, the Oriental and Eastern Orthodox Churches, Protestants, and Old Catholics all agree on fundamentals such as Christology and the Trinity, Jehovah’s Witnesses have diverged so far from fundamental Christian beliefs that it is debatable whether they are really Christians. For example, they believe that 144,000 people will live in heaven, while everybody else will rise from the dead to live in an earthly paradise, and that there is no hell. They also believe that the invisible Second Coming of Jesus took place in October 1914, when he supposedly commenced his kingship in heaven. These are just a couple of their very peculiar beliefs that illustrate just how far removed they are from what most people would consider to be Christian beliefs.
