Do you think there was once a tangible, practical reason for the prohibition on pork, shellfish, blood, found in the Bible/Qur’an? (I’m most familiar with these, so my question will be based on Judeo-Christian restrictions, but feel free to bring up other religions as well). In the case of pork, one could point to the dirty behavior of the pig, and shellfish contains common allergens. But that isn’t necessarily where the restrictions originate. I’m just throwing out ideas.

Jehovah’s Witnesses take the prohibition on consuming blood to the extreme of not allowing blood transfusions. Are there other cultures and religions with taboos about the consumption of blood?

What do you think is the reasoning behind these restrictions? Any theories or sources are welcome.