> Calcifediol becomes active more quickly than cholecalciferol, enough so that if I were in the business of defending the Spanish study I might argue that it ta

> Calcifediol becomes active more quickly than cholecalciferol, enough so that if I were in the business of defending the Spanish study I might argue that it takes a few weeks for cholecalciferol to work, so giving it to someone who will already be dead or recovered by then is meaningless. Yes, this is one possible conclusion of these experiments. It sounds to me like the mechanisms/pathways of vitamin D are well understood and not controversial. It is known that there can be very long delays (weeks) until blood levels increase from food supplements, and it is blood levels at the time of infection that matters. The results confirm all this. > It would make me more comfortable if someone who did understand Vitamin D biochemistry would confirm this, but I'm not going to hang the whole argument on it. Ok, then. Thanks anyway.