There’s been a lot written about vitamin K recently. It’s similar to where vitamin D was a few years ago. It turns out that vitamin K is lot more important than we thought; it has many roles in the body we never knew about, and we need quite a bit more than was previously thought.
Until recently, Vitamin K was known only for its ability to help blood clotting. In fact people on anticlotting medications (blood thinners like Coumadin) are still often given some bad advice by their doctors: they’re told to avoid green vegetables because they’re high in vitamin K. Green vegetables are of course among the healthiest foods on the planet, and we now know that vitamin K is a lot more than just a “clotting vitamin.” It’s even vital to prevent the very heart disease blood thinners are prescribed to address. Although I believe there are much healthier alternatives to taking blood-thinning medications, if someone is going to take them, better advice would be to keep intake of foods rich in vitamin K relatively consistent from day to day, so that drug dosage can be calibrated accordingly.
What’s been investigated more recently is vitamin K’s role in regulating calcium in the body. It’s the answer to the “calcium paradox” – a situation where people take lots of calcium to build bone, but the calcium goes to their arteries instead. There’s a protein in bone (osteocalcin) that attracts calcium and draws it into the bone matrix; there’s another protein (matrix Gla-protein, or MGP) that powerfully inhibits calcification in the blood vessels and other soft tissues. Both of these proteins are “turned on” by vitamin K; so vitamin K basically tells calcium where it should go and where it shouldn’t go, preventing both osteoporosis and heart disease.
Vitamin K may prevent other illnesses as well. It may protect the brain and help to prevent dementias, like Alzheimer’s disease, and may have a role in preventing cancer and diabetes. We already know it is an antioxidant and reduces inflammation, and that it stimulates the production of energy.
The RDA is based solely on the amount of vitamin K needed for clotting purposes. While most people get enough to prevent bleeding disorders, quite a bit more vitamin K is required if other needs are to be met. There’s not yet a good way to measure vitamin K with blood tests to see whether or not you’re deficient, but using unactivated osteocalcin and unactivated MGP as markers of vitamin K deficiency, population studies have found widespread deficiencies among healthy adults. I think you can assume that if you’re not supplementing you probably are deficient. Apart from excessive bleeding, a symptom of very gross vitamin K deficiency, there are no discernible symptoms. You may of course be losing bone or developing atherosclerosis without being aware of it! Meanwhile, toxicity studies have shown that taking many times the current RDA is safe.
It’s also been found that one form of vitamin K (vitamin K1) is most active in clotting, whereas another form (vitamin K2) is more active in calcium regulation. Whereas vitamin K1 can be converted into K2 in the body, there are advantages in ingesting both forms. Some people are now recommending very high daily doses of vitamin K2, however I’m not yet convinced that such high levels are necessary. I’m quite comfortable with the amounts in our Multi: 500 mcg of K1; Bone Mineral Formula: 750 mcg of K1 and 250 mcg of K2. Our vitamin D3 capsules also contain 10 mcg vitamin K2 per gelcap.