Book Review: Vitamin K-2 and the Calcium Paradox: How a Little-Known Vitamin Could Save Your Life

By Kate Rheaume-Bleue (Collins, 2012)

Reviewed by Rosalind Michahelles

The paradox in the title refers to the fact that – according to the author’s research — dietary calcium, unaccompanied by vitamin K-2 may well end up in soft tissue like blood vessels rather than in bones and teeth. In other words, it may harden your arteries rather than strengthen your bones and your teeth. Apparently vitamin K-2 plays a crucial stimulating role where two proteins are concerned: one is osteocalcin, which pulls calcium into bones; the other is matrix gla protein (MGP) which pulls calcium out of soft tissue. Vitamin K-2 thus provides a twofold benefit.

What about the more famous vitamin K-1, you may be asking. K-1 – philiquinone – comes from plants like leafy green vegetables and is important in the blood clotting function. That is why patients on blood-thinners like warfarin are advised to avoid kale and spinach and such. Some K-2 will be made in the body from K-1 but by far the more important source is dietary. Good sources of K-2, according to the studies the author refers to, are (a) the fat of grass-fed animals, which means goose liver and some cheeses like Gouda and Brie, among other menu items and (b) natto, a Japanese soybean ferment. Natto is hard for most people to like on the first couple of tries. But those in Japan who eat it seem to have the strongest bones.
Vitamins A and D collaborate with K-2 in ways that allow one to pick up the slack when the other one is short. In this “sparing action” (p.201), sufficient vitamin A means less K-2 is needed. Cooperatively, vitamins A and D operate a “switch mechanism,” whereby a small amount of either guards against toxicity from too much of the other (p.203).
One unfortunate scenario has unfolded from taking generous supplements of calcium and vitamin D without the accompaniment of A and K-2. Vitamin D helps draw calcium from the intestines into the blood stream – but then what? Without the other vitamins it can lodge in arterial plaque, increasing the likelihood of heart problems. The coronary artery calcium test is one way to find out if that’s happening. Another potential problem is that kidney stones may form when excess calcium builds up in urine.
How to test for K-2 deficiency? One possibility is to test for inactivated osteocalcin in the blood. It will be in inverse relation to vitamin K-2, as K-2 is the principal activator of osteocalcin. If you do decide to take a supplement, be sure that all three vitamins are coming in, either through diet or pills. Vitamin K-2 comes in two flavors, so to speak. Menaquinone-4, which in nature comes from animals, is synthetic when in supplements. MK-7, on the other hand, comes from natto. The author, who is Canadian, says that MK-4 is less effective such that a larger and more frequent dose is recommended; MK-7 is thus the gold standard.
If you have problems with bones or teeth or arteriosclerosis or varicose veins or kidney stones, this interesting book is worth reading. One lesson I got from it – once again – is that food is our best medicine but when the food supply strays from nature we should look to supplements, but in moderation. Beef used to provide vitamin K-2 because cows ate grass; now that they eat corn and soy, etc., we may well need vitamin K-2 supplements to ward off osteoporosis, tooth decay, and heart disease.
Rosalind Michahelles is a certified holistic health counselor in Cambridge. For questions about this essay or related issues please call 617-491-3239 or visit