Why are some people so tolerant to alcohol?
Why is it that some people are so tolerant to alcohol whereas other people just need to get a whiff to tip them over the edge?
That's to do with an enzyme called alcohol dehydrogenase which contains a zinc atom. Different amounts of this enzyme would be expressed in people who have different genetic make up. This is one part of the answer. If you are a regular user you boost the enzymes in the liver to increase the numbers so you break these things down a little bit more.