Vitamin K, which is best known for its role in blood clotting, is also an essential nutrient for bone formation. Apart from playing a key role in bone health, vitamin K deficiency is linked to cardiovascular health, insulin resistance and Alzheimer’s disease. In bone health, vitamin K and D are synergistic nutrients in calcium and bone metabolism. Without vitamin K sufficiency through dietary intake, and or supplementation, vitamin D therapy and its benefit in calcium optimization, may not adequately benefit bone calcification, and could lead to calcification of arteries and atherosclerosis.
Numerous studies provide evidence for an association between a low dietary vitamin K intake and an enhanced risk for fractures from osteoporosis. In a 10-year study of 72,327 women (Nurses Health Study), the highest dietary vitamin K (110 micrograms /day) intake correlated to a 30% reduced risk of hip fracture. (9) Similarly, a population of 800 elderly men and women participating in the Framingham Heart Study, found that those with the highest vitamin K (K1) intake, 250 mcg/day, had a threefold reduction in hip fracture risk. (10) Note that the aforementioned studies along with many others on vitamin K and bone health, conclude a benefit in the reduction of fractures, and perhaps preventing bone breakdown (resorption), rather than implying that vitamin K alone actually contributes to bone formation.
There are also genetic factors that influence vitamin K sufficiency in many individuals. Approximately one quarter of the US population carries the ApoE4 gene that not only is a risk factor for Alzheimer’s and cardiovascular disease, but for poor vitamin K status as well. ApoE, a functional component of blood fat and protein complexes (lipoproteins), transports vitamin K (K1) primarily via triglyceride rich lipoproteins (chylomicrons).(11,12) In ApoE4 gene types (genotype), vitamin K laden lipoproteins are taken up and cleared by the liver more readily with the resultant lower circulation vitamin K. Conversely, a person that that carries an ApoE2 gene, has higher circulating vitamin K due to decreased uptake and clearance by the liver of the ApoE2 associated lipoproteins. ApoE4 genotypes may need to have more vitamin K intake to maximally carboxylate/modify osteocalcin. (12)
Given the genetic characteristics and dietary patterns of many individuals, supplementation may be necessary to sufficiently modify osteocalcin to form strong bones and prevent bone loss. Several studies have shown that doses of I mg. (1,000 micrograms) to 45 mg. of vitamin K had beneficial outcomes in optimizing osteocalcin function and increasing bone mass density. The obvious question that follows, is what may be the right dose for you? In research that examined what doses of vitamin K were needed to maximally carboxylate (modify) osteocalcin, one study demonstrated an increasing modification, or carboxylation of osteocalcin by 1 mg. of vitamin K1 over doses of 250, 375, and 500 micrograms (mcg.). Another study administered 86, 200, and 450 mcg. of K1 after first inducing a deficiency state of vitamin K by allowing only 18 mcg. of vitamin K in the diet. Carboxylated or modified osteocalcin remained low in the group that received 450 mcg. of K1. (12) The takeaway? To replete vitamin K levels for the maximal carboxylation of osteocalcin and to benefit bone mass density, higher intake through supplementation is probably necessary and prudent. Based on the above research, I strongly recommend a minimum of 1,000 mcg. (1 mg.) of vitamin K daily for most healthy individuals. Since ApoE 4 genotypes may need to compensate for lower circulating K, it would be prudent to increase intake of vitamin K from diet and through supplementation if you are an ApoE4 genotype. More research is needed to establish optimal doses for ApoE4 genotypes, albeit if 1,000 mcg. is optimal for most healthy individuals, significantly more may be needed to override the influence of ApoE4 on vitamin K sufficiency. As obvious the need for maximizing vitamin K for healthy bones and a healthy circulatory system (see below), a combination of nutrients will ultimately render the desired clinical benefits through synergy. Rarely is one nutrient a panacea.
Vitamin K Synergy
Vitamin K and D are synergistic in healthy calcium regulation and bone formation. The use of vitamin K with vitamin D may substantially reduce bone loss. In a study combining vitamin D3 (Cholecalciferol) and vitamin K2, bone formation in patients with primary osteoporosis, resulted in an increase in lumbar bone mineral density. (13) Another study demonstrated found that vitamin K at I gram/day, significantly enhanced the effectiveness of supplementation with calcium, vitamin D, and magnesium and zinc, in preventing bone loss. (14) Yet in another example of vitamin K and an integrated approach to therapies for osteoporosis, a study found that Vitamin K augmented hormone replacement therapy (HRT) in postmenopausal osteoporosis. The study showed that declining bone mass density in individuals on HRT alone, improved with vitamin K (K2) therapy. (15)
Symptoms & conditions related to vitamin K deficiency:
• Gastrointestinal bleeding
• Calcification of soft tissue, especially heart valves
• Digestive problems, especially malabsorption
• Cardiovascular Disease
• Malabsorption syndromes
Vitamin K In Foods
Some of the best sources of vitamin K (K1) are kale, collard greens, broccoli, spinach and other green leafy vegetables. Intestinal bacteria also produce some vitamin K (K2). K2 is also supplied by chicken, egg yolk, butter, cow’s liver, certain cheeses and fermented soybean products such as natto. The body stores very little vitamin K; small amounts of this vitamin are deposited in the liver and in the bones, but this amount is only enough to supply the body’s needs for a few days. Absorption of vitamin K from vegetables is enhanced by the presence of dietary fat in the same meal. Please see the chart below for the healthiest sources of vitamin K.
When one considers that the average American adult consumes
The Calcification Paradox
In animal research, vitamin D is used to create heart disease-hardening of the aorta (arterial calcification). In vitamin D therapy, vitamin K prevents calcium buildup the arteries while facilitating normal bone growth and development. Insufficient intake of dietary vitamin K may increase the risk of vascular calcification and subsequent hardening of the arteries. Vitamin K enables the deposition of calcium onto the bone while preventing the deposition of calcium onto the arteries. Osteoporosis and atherosclerosis (hardening of the blood vessels), is in many individuals a related biological phenomena and has been termed the “calcification paradox”. A deficiency of vitamin K is not only understood to be a central feature of decreased bone density and risk for fractures as described above, but in calcification of the arteries as well. This calcification paradox is not an uncommon clinical finding in aging individuals with several studies indicating that postmenopausal women are at increased risk. (16) Supplementing with vitamin D to optimize calcium status in individuals may put them at risk for calcification and hardening of the arteries. Optimal vitamin D supplementation must be accompanied by plentiful dietary and supplemental vitamin K for not only healthier and stronger bones, but for vascular health as well. If you supplement with vitamin D, look for a product (i.e. Vitamin D Synergy & Vitamin D Supreme ) that also has vitamin K with it to safeguard against calcification and hardening of your arteries, or take a separate vitamin K formula that includes both K1 & K2 (i.e. Tri-K ).
Although allergic reaction is possible, there is no known toxicity associated with high doses of supplemental forms of vitamin K1 and K2. (5) Those taking medications to thin the blood, such as Coumadin, should consult with their physician before increasing consumption of foods high in vitamin K. Supplemental vitamin K does not cause the blood to clot excessively in healthy people. However, this does not mean that no potential exists for adverse effects resulting from high intakes. Intake of doses higher than otherwise would be available from a healthy diet should only do so with the supervision of a qualified practitioner.
A serum assay for undercarboxylated osteocalcin (ucOC), is an excellent test for vitamin K sufficiency, and is now available from FunctionalHealthSolutions.com.
If you are reading this through a source other than FunctionalHealthSolutions.com and you wish to read Part 1 and the vitamin D portion of this article, visit the Bone Health category in the Article & News section @ FunctionalHealthSolutions.com
9. Vitamin K intake and hip fractures in women: a prospective study.
10. Dietary vitamin K intakes are associated with hip fracture but not with bone mineral density in elderly men and women.
11. Metabolism and cell biology of vitamin K
12. Transport of vitamin K to bone in humans : Nutritional advances in human bone metabolism
13. Efficacy of combined administration of vitamin D3 and vitamin K2 for primary osteoporosis. Iwamoto J.
14. Vitamin K1 supplementation retards bone loss in postmenopausal women between 50 and 60 years of age.
15. Treatment for patients with postmenopausal osteoporosis who have been placed on HRT and show a decrease in bone mineral density: effects of concomitant administration of vitamin K(2).
16. Vitamin K in the treatment and prevention of osteoporosis and arterial calcification. Adams J, Pepping J.;