I've read that there are certain vitamins/substances(not referring to NSAIDS) that antagonize vitamin K; one of them being vitamin C. In the link below, it placed vitamin C as an agonist, which goes against what I previously read. I usually take vitamin K with calcium, thinking that it's a good idea, but Ca in the link is listed as an antagonist.
Vitamin and Mineral Agonists and Antagonists
Vitamin and Mineral Agonists and Antagonists