Vitamin K is finally getting the attention—and the respect—it so richly deserves. It’s comprised of two structurally related (but very different acting) compounds, vitamin K1 and vitamin K2. Vitamin K1 is primarily found in green leafy plants such as lettuce and spinach. Vitamin K2 is primarily synthesized by bacteria in the colon, although it’s available in some foods (see below).
Vitamin K1 is found in leafy greens—even lettuce—so it’s relatively easy to get from your diet. Vitamin K2 is trickier. It’s found mainly in animal foods like egg yolks, cheese and dark chicken meet or in fermented foods like natto and sauerkraut.
The most important thing that vitamin K1 does is help the body with clotting. That’s why doctors tell you to “avoid” green leafy vegetables when you’re on Coumadin, a popular drug which is frequently given to thin the blood of patients who are prone to blood clots.
(The advice to take Coumadin while avoiding green leafy vegetables may be well past its expiration date at this point, but that’s a discussion for another day.)
Vitamin K2, on the other hand, does a whole bunch of other things having nothing to do with clotting. For one thing, it’s vitally important for strong healthy bones. Why? Because vitamin K is necessary to make a bone-related protein called osteocalcin. Without vitamin K, osteocalcin either doesn’t get made or doesn’t work very well, and without osteocalcin minerals like calcium can’t bind to bone. So, in a metaphorical sense, vitamin K acts like a traffic cop, making sure calcium winds up where it belongs—in the bones (and teeth)—and not where it doesn’t (in the arteries!). And that brings us to the second, very important role of vitamin K2 in heart health.
See, keeping calcium in the bones where it belongs is only one side of the coin. The other side is keeping calcium out of the arteries, where it most definitely does not belong! (Remember “hardening of the arteries?” Well, that’s calcium showing up where it has no business being!) That’s why vitamin K2 is gaining such a strong reputation as a heart-healthy nutrient—which it is!
Vitamin K2 is found in fermented foods, such as sauerkraut, natto, and some cheeses (many of which most people don’t eat). The situation is made worse by the fact that antibiotics wipe out so many of the bacteria that normally produce vitamin K2 in the colon. Because I don’t think most people get enough K (especially K2), I almost always recommend supplementing.
Vitamin K2 comes in two forms—MK4 and MK7. Both are good, but the MK7 is longer acting. Remember to take vitamin K with a meal containing some fat. Along with vitamins A, D and E, vitamin K is a fat-soluble vitamin and better absorbed when consumed with some healthy fat.
At least once a year, an interviewer will ask me to name the ten supplements I think are most important for their readers to take. I always explain that no routine will suit everyone and that everybody’s different. That said, I do have a basic list of go-to supplements that I think just about everyone would benefit from. A couple of years ago I added vitamin K2 to that list of core supplements. I now consider it cornerstone nutrient for both the heart and the bones.
Weider Global Nutrition just launched a K2 product I like a lot called Artery Health which combines the MK-7 form of K2 with a couple of powerful antioxidants like ginger. And it’s easy to find—you can get it all over, including Costco and Amazon and a whole bunch of other places.