I'm looking at this diagram of homocysteine metabolism and see two distinct pathways that the amino acid may get metabolized to: with vitamin B12 it gets converted back into methionine, while with B6 ...
From what I understand, your body needs certain amounts of vitamins and minerals to maintain health. Why can't we just take enough pills to obtain these vitamins and minerals?
All herbivores produce vitamin B12 de novo. Gorillas, for example, are "vegans" so I suppose some human ancestor was also herbivore. Have we ever been B12 self-producers? If so, why have we lost that ...