Chris Kresser: I don’t know about that. I mean, if you think about this in terms of food, which is the way that our ancestors got vitamin K2, in MK-4 form, which is the form that’s typically found in most foods except fermented foods. They may or may not have been eating it three times a day. Maybe they ate it just one time a day and they had a big meal with organ meat that had vitamin K2. I just don’t know that we have enough research to get that specific or that it matters that much. I think it’s easy to get hung up on these details, but we need to consider patient compliance and just things from an evolutionary perspective. I do agree that both the MK-4 and the MK-7 forms can be effective. I previously recommended only MK-4, but I’ve changed my mind on that after reading more of the research.
In terms of the ratios, again, I don’t think we have enough research to be really specific. A lot of the research on ratios of A and D and K2 have come from broiler chickens. That’s relevant, but I’m not super-impressed with the quality of that research, and when you think about it from an evolutionary perspective, you can be sure that our ancestors weren’t sitting there thinking, OK, I can take a bite of this, but then I have to balance that with a bite of this organ meat over here that has K2. I’m partly serious. I think we get a little too hung up on these details, and we’re talking about the last 1 percent. It’s true that you don’t want to have a vitamin A-to-D ratio that’s way out of line. Taking way too much A and not enough D and K2 can cause a toxicity problem with vitamin A, and those should be balanced in a ratio, but you’ll get that ratio, I think, from just eating the nutrient-dense foods that our ancestors ate, and you don’t need to really think that much more about it.