The whole idea is that some research suggests that vitamin D may be harmful without vitamin K to offset its effects ("so that calcium doesn't build up in the ve

The whole idea is that some research suggests that vitamin D may be harmful without vitamin K to offset its effects ("so that calcium doesn't build up in the vessels but goes to the bones where it's supposed to be"). That's all there is to it. No need to discuss absorption. Furthermore, the idea "taking D and K at the exact same time reduces the absorption of D" is unsubstantiated in medical research