Vitamin K helps prevent vascular calcification, improves
Richard Wood, Ph.D., is a researcher from Tufts University in Boston, where
he directs the Mineral Bioavailability Laboratory at the USDA Human Nutrition
Center on Aging. Dr. Wood presented an overview of the data concerning the newly
discovered importance of vitamin K in regulating calcium metabolism and
preventing both bone fractures and vascular and other soft-tissue calcification.
Until recently, vitamin K has been seen strictly as a pro-clotting factor,
Wood pointed out. It regulates prothrombin, Factors VII, IX and X. But it is the
newly discovered importance of vitamin K in regulating calcium deposition that
makes it one of the key players in anti-aging protocols, especially in view of
the fact that we tend to become increasingly deficient in vitamin K as we age.
Postmenopausal women show lower levels of carboxylated ostecalcin compared to
premenopausal levels, indicating a vitamin K deficiency.
Poor vitamin K status has been found to raise the risk of a heart attack 2.4
times-as much as smoking, Wood pointed out. The most likely reason is that
vitamin K helps prevent vascular calcification. Wood explained that vitamin K is
a limiting factor in the carboxylation of various bone-regulating proteins that
help prevent bone formation in the wrong places, including the middle layer of
the arterial wall.
Vitamin K was discovered to be a cofactor in the chemical reaction that adds
the carboxyl group (COOH) to glutamate, making it possible for bone-regulating
proteins such as osteocalcin to bind calcium. Osteocalcin is produced in the
osteoblasts, cells that create new bone. It should be noted, however, that
osteocalcin and related proteins have been found not only in bone, but also in
soft tissue the brain, pancreas, and lungs. The speaker mentioned that one of
the important vitamin K-dependent proteins is the matrix Gla protein, a potent
inhibitor of soft-tissue calcification when it is sufficiently carboxylated.
In Japan, vitamin K has been approved for the treatment of osteoporosis, in
combination with vitamin D3. Several epidemiological studies have found a
significant increase in the risk of fractures associated with vitamin K
deficiency. In particular, Wood cited the Framigham Heart Study. Those in the
highest quantity of vitamin K intake showed a 65% reduction in hip fractures
compared with those in the lowest quantity. In other words, those consuming the
most vitamin K had only about a third of the hip fractures of those consuming
the least vitamin K.
Wood emphasized, however, that studies have not found any effect of dietary
intake of vitamin K on mineral bone density. A study of bone markers in Japanese
children has strongly suggested that vitamin K, which increases levels of
carboxylated osteocalcin, affects primarily bone quality, which translates into
resistance to fracture, rather than mineral density.
Vitamin K intake was also found to be inversely correlated with aortic
calcification, an important predictor of heart attack risk. Patients whose
aortic calcification was evident in X-ray images had more undercarboxylated
osteocalcin, indicating poor vitamin K status. Poor vitamin K status has been
found to triple the risk of severe vascular calcification, Wood stated.
Deficiency of vitamin K leads to undercarboxylation, and hence inactivity of
bone-regulating proteins such as matrix Gla protein, resulting in soft-tissue
calcification. And the greater the degree of calcification, the greater the risk
of a heart attack.
Warfarin (Coumadin), an anticoagulant, depletes vitamin K and causes severe
vascular calcification in rats. Bisphosphonate drugs can prevent this harmful
side effect. Coumadin patients cannot take vitamin K supplements and are even
told to avoid foods rich in vitamin K.
Though the speaker did not go into the neuroprotective role of vitamin K, it
is worth noting that some researchers think that supplementing with vitamin K
may help prevent Alzheimer's disease and ward off stroke. This is due to the
ability of vitamin K to reduce neuronal damage by protecting the vascular
system, guarding against inflammation and blocking excess infiltration of
calcium into brain cells. Vitamin K is also involved in regulating important
brain enzymes and growth factors. It seems that we are discovering more and more
functions of this remarkable anti-aging vitamin.
Vitamin K from supplements is more bioavailable than dietary vitamin K, Wood
pointed out. Since vitamin K is fat-soluble, it's a good idea to add olive oil
(itself a source of vitamin K) or another healthy fat when you eat dark green
vegetables such as spinach, broccoli, kale, green cabbage, brussels sprouts or
lettuce (even pale lettuce such as iceberg supplies some vitamin K). Green
plants supply the form of vitamin K called phylloquinone, or vitamin K-1. Our
intestinal bacteria convert K1 to K2, or menaquinone (actually there are several
menaquinones), the active hormonal form. Some menaquinone is also found in
fermented products such as cheese or natto, a fermented soybean product, and in
liver, meat and egg yolk.
As has been jocularly observed, as we age, we turn to stone. We calcify. More
accurately, our arteries and organs calcify, while our bones decalcify. Vitamin
K is an essential resource against this pathology of aging.
The role of dysregulated calcium metabolism in aging-related degenerative
disorders, as well as the corrective role of magnesium, vitamin D and vitamin K,
is finally beginning to get much-deserved attention. Supplementation with
calcium alone is obviously not enough; some think it might even be harmful. It
is critical to help the aging body control calcium. Vitamin K is the latest
addition to our arsenal.