Vitamin K

Why It Matters for Longevity

Vitamin K is an essential cofactor for blood clotting proteins (factors II, VII, IX, X) and for the carboxylation of osteocalcin (bone matrix protein) and matrix Gla protein (MGP, which prevents arterial calcification). Deficiency leads to impaired coagulation, reduced bone mineralization, and accelerated vascular calcification.

Longo recommends ensuring adequate vitamin K intake via a multivitamin every 2–3 days and through green leafy vegetables. Plant foods (kale, spinach, broccoli) provide vitamin K1 (phylloquinone); fermented foods and some animal products provide K2 (menaquinones), which has greater affinity for vascular and bone tissues.

Gast et al. (2009) analyzed 16,057 women in the Prospect-EPIC cohort and found that each 10 mcg/day higher dietary K2 intake was associated with a 9% reduction in coronary heart disease — with K2 showing substantially stronger cardiovascular effects than K1 at comparable intakes.

Knapen et al. (2013) conducted a 3-year RCT showing that low-dose MK-7 supplementation (180 mcg/day) significantly reduced the age-related decline in bone mineral density and bone strength in healthy postmenopausal women, with statistically significant preservation of bone stiffness.

The Rotterdam Study: Menaquinone and Atherosclerosis

The landmark epidemiological data come from the Rotterdam Study, a population cohort of 4,807 subjects followed for approximately 10 years from 1990 to 2000. Geleijnse et al. (2004) found that participants in the highest tertile of dietary menaquinone intake had a relative risk of 0.43 for CHD mortality compared to the lowest tertile — a 57% reduction — and an odds ratio of 0.48 for severe aortic calcification. All-cause mortality was also lower in the top tertile (RR 0.74). Critically, phylloquinone (K1) intake showed no relationship to any of these outcomes, establishing that the cardiovascular protection was specific to K2 forms. The biological mechanism is MGP carboxylation: undercarboxylated MGP allows calcium to deposit in arterial walls, while K2-activated MGP sequesters calcium ions and prevents their precipitation in vascular smooth muscle. Geleijnse et al., 2004, J Nutr

K1 vs K2: Different Kinetics, Different Targets

Phylloquinone (K1) is abundant in leafy greens and has a plasma half-life of approximately 1 hour; it is directed primarily to the liver, where it activates coagulation factors. Menaquinone-7 (MK-7) from natto has a plasma half-life of ~72 hours, enabling sustained activation of extra-hepatic K-dependent proteins — specifically osteocalcin in bone and MGP in arterial walls. This pharmacokinetic difference, not merely dose, explains why K2 shows effects on vascular and bone outcomes that K1 does not.

MK-4 (found in small amounts in eggs and some meats) and MK-7 (concentrated in natto at ~1,000 mcg/100g) are the best-studied forms. Longer-chain menaquinones such as MK-8 and MK-9 appear in fermented dairy (particularly Dutch-style hard cheeses), though their bioavailability and carboxylation efficiency differ from MK-7.

Vascular Calcification: Meta-Analytic Evidence

A 2023 systematic review and meta-analysis of 14 RCTs enrolling 1,533 participants found that vitamin K supplementation significantly slowed coronary artery calcification progression (mean difference −17.37, 95% CI: −34.18 to −0.56, p=0.04) and markedly reduced dephospho-uncarboxylated MGP (dp-ucMGP) levels (MD −243.31, 95% CI: −366.08 to −120.53, p<0.0001). Dp-ucMGP is a validated biomarker of vascular K-deficiency: higher values indicate more inactive, calcium-permissive MGP in arterial tissue. Nine of the 14 trials used MK-7 specifically. Adverse event rates were not different from control groups. Li et al., 2023, Front Nutr

This meta-analytic signal does not yet establish clinical outcomes such as reduced cardiovascular events in general populations, and studies in chronic kidney disease — where vascular calcification is most severe — have been more equivocal. The evidence is strongest for slowing the biomarker trajectory (CAC score and dp-ucMGP) rather than for downstream mortality reduction.

Osteocalcin, Bone Mineralization, and the K-D Axis

Osteocalcin is a small bone matrix protein synthesized by osteoblasts; it requires gamma-carboxylation by vitamin K to bind hydroxyapatite and direct calcium into the bone crystal lattice. Carboxylated osteocalcin also functions as an endocrine signal, promoting insulin secretion and improving glucose tolerance — a pathway linking bone quality to metabolic health. Vitamin D3 stimulates osteocalcin gene expression, while vitamin K2 activates the resulting protein; the two vitamins operate on the same downstream target through different steps, which is why co-supplementation is widely used in bone health trials.

Knapen et al. (2013) demonstrated in the 3-year MK-7 RCT that 180 mcg/day significantly preserved femoral neck bone mineral content and stiffness in postmenopausal women, with the bone stiffness index (combining BMD and geometry) showing a statistically significant advantage over placebo. The effect was modest in absolute terms but sustained over 3 years and occurred without calcium co-supplementation — pointing to improved mineral utilization rather than increased mineral supply. Knapen et al., 2013, Osteoporos Int

Warfarin Interaction

Patients on warfarin (a vitamin K antagonist) must maintain consistent, not absent, vitamin K intake. Wide fluctuations in dietary K1 interfere with INR stability; the standard clinical advice is not to avoid vitamin K–containing vegetables but to consume them at a consistent daily amount so that dose adjustments can be calibrated. High-dose K2 supplements in anticoagulated patients have not been systematically studied and warrant medical guidance.

How to Use It

Pairs well with kale, spinach, broccoli. Use as a nutrient in your daily meals according to the Longevity Diet guidelines. Kale provides ~817 mcg K1/100g raw; spinach ~483 mcg; broccoli ~102 mcg. Natto is the only outstanding K2 source (~1000 mcg/100g MK-7). Drizzle olive oil on leafy greens to increase K1 bioavailability, since phylloquinone is fat-soluble and absorption is minimal from fat-free meals.

What to Pair It With

Synergies

• Vitamin D (synergy): Vitamin D promotes calcium absorption and osteocalcin synthesis; vitamin K2 activates osteocalcin via carboxylation, directing calcium into bone rather than soft tissues. Co-supplementation is widely recommended for bone and vascular health.
• Calcium (synergy): K2 activates matrix Gla protein (MGP) and osteocalcin, which guide calcium into bone and prevent arterial calcification; without adequate K, calcium supplementation may increase vascular calcification risk.
• Olive Oil (complement): Dietary fat is required for absorption of fat-soluble vitamin K1 from vegetables; drizzling olive oil on leafy greens significantly increases phylloquinone bioavailability.

Flavor Profile

Category: supplement/nutrient.

The Science

• Gast et al., 2009, Nutr Metab Cardiovasc Dis: Each 10 mcg/day higher K2 intake was associated with 9% lower coronary heart disease risk in 16,057 women (Prospect-EPIC); K2 effects were substantially stronger than K1.
• Knapen et al., 2013, Osteoporos Int: 3-year RCT of MK-7 (180 mcg/day) in healthy postmenopausal women: significantly reduced age-related bone mineral density decline and preserved bone stiffness vs placebo.
• Geleijnse et al., 2004, J Nutr: Rotterdam Study cohort of 4,807 subjects over 10 years: highest tertile menaquinone intake associated with RR 0.43 for CHD mortality and OR 0.48 for severe aortic calcification; K1 showed no association.
• Li et al., 2023, Front Nutr: Meta-analysis of 14 RCTs (1,533 participants): vitamin K supplementation significantly slowed coronary artery calcification (MD −17.37, p=0.04) and reduced dp-ucMGP (MD −243.31, p<0.0001).

References

1. Gast GC, de Roos NM, Sluijs I, et al. A high menaquinone intake reduces the incidence of coronary heart disease. Nutr Metab Cardiovasc Dis. 2009;19(7):504-10. PMID: 19179058. doi:10.1016/j.numecd.2008.10.004
2. Knapen MH, Drummen NE, Smit E, Vermeer C, Theuwissen E. Three-year low-dose menaquinone-7 supplementation helps decrease bone loss in healthy postmenopausal women. Osteoporos Int. 2013;24(9):2499-507. PMID: 23525894. doi:10.1007/s00198-013-2325-6
3. Geleijnse JM, Vermeer C, Grobbee DE, et al. Dietary intake of menaquinone is associated with a reduced risk of coronary heart disease: the Rotterdam Study. J Nutr. 2004;134(11):3100-5. PMID: 15514282. doi:10.1093/jn/134.11.3100
4. Li T, Wang Y, Tu WP. Vitamin K supplementation and vascular calcification: a systematic review and meta-analysis of randomized controlled trials. Front Nutr. 2023;10:1115069. PMID: 37252246. doi:10.3389/fnut.2023.1115069

Key Nutrients