You mentioned that vitamin K supplementation may be contraindicated for people on warfarin. Does that include Plavix in the case of a patient with stents who is supplementing with D? Can they get enough from animal sources to balance that?

Chris Kresser:  Yeah, it would include any anticoagulant drug. Vitamin K is definitely contraindicated. There’s some controversy about whether K2 affects the coagulation pathways and thus should be avoided with anticoagulant drugs. Some say yes and some say no. Personally I would be conservative in that situation, and I would have them try to get vitamin K2 from food. And, yes, I do believe you can get enough K2 from food, and that’s definitely how our ancestors did it. Unless you’re going for therapeutic use for a bone density issue, just eating pasture-raised dairy if that’s tolerated, fermented foods, and then if you can stomach the taste of natto, that’s a really good source as well. I personally can’t, but fortunately I do well on pasture-raised dairy and fermented foods.