Vitamin ·Strong evidence ·Reviewed May 2026
Directs calcium to bones and teeth while preventing arterial calcification. Critical partner for vitamin D3 supplementation.
The bottom line
Evidence rating strong. Most-documented uses: bone health, cardiovascular health, calcium metabolism. 19 sources indexed (2004–2024), with 20 interaction records on file.
Core mechanism
Activates osteocalcin (directs calcium into bone matrix) and matrix GLA protein (MGP, prevents calcium deposition in arteries and soft tissues) through gamma-carboxylation of glutamic acid residues.14,3
Ranked by evidence and value.
Real-world pricing across three quality tiers. Assumes Vitamin K2 MK-7.
Assumes about 90-200 mcg/day. MK-7 is usually the default K2 market and is moderately priced for a once-daily fat-soluble vitamin. Updated 2026-04-02.
How much you'd eat to match a supplemental dose.
Natto is the standout food source of MK-7.
Consistent natto intake is uncommon outside targeted diets.
Timing: With a meal containing fat
Avoid self-starting if you take warfarin or another vitamin K-sensitive anticoagulant.
Timing: With dinner
Typically paired with vitamin D3 rather than used alone.
What to test, the optimal window inside the conventional range, and how long a response takes.
Where this appears in the symptom-to-supplement map, ranked by relevance.
K2 supports carboxylation of bone-related proteins such as osteocalcin.13,1
Avoid if you use warfarin unless supervised.
MK-7 directs calcium into bone and away from arterial walls via osteocalcin activation.14,1
Pair with D3 and calcium.
Vitamin K2 activates matrix Gla protein and osteocalcin, which help direct calcium into mineralized tissue, a mechanism of emerging interest for dental health.14,1
Direct dental evidence is limited; often paired with D3 and calcium. Check with a clinician if you take warfarin or other anticoagulants.
Vitamin K2 (MK-7) supports osteocalcin activation and may modestly support alveolar bone integrity.3,4
Often paired with vitamin D3.
Vitamin K2 activates osteocalcin, a protein that helps bind calcium into the bone matrix, which may support bone mineral quality.1,3
Avoid or supervise if on warfarin; treat as adjunctive support alongside medical care.
Fat-soluble vitamin K is poorly absorbed in steatorrhea, and deficiency can impair clotting and bone metabolism.
Do not start if you take warfarin without clinician oversight, since vitamin K alters its effect.
Evidence-based stacks that include it, with the exact dose and timing each one uses.
Supports vitamin K-dependent proteins involved in calcium handling; avoid self-starting with warfarin or vitamin K-sensitive anticoagulants.9,14
Supports vitamin K-dependent proteins involved in vascular calcium biology; avoid self-starting with warfarin.9,14
Vitamin K2 activates osteocalcin, a protein that helps bind calcium into the bone matrix, and may help direct calcium toward bone rather than soft tissue. Evidence for an independent bone density benefit is mixed and still developing, so it is positioned as a supporting cofactor.14,3
Vitamin K2 activates osteocalcin, a protein that helps bind calcium into the bone matrix, and may support directing calcium toward bone rather than soft tissue. Evidence for fracture prevention in well-nourished populations is still developing.14,3
Vitamin K intake has special relevance for people using warfarin because VKORC1 and CYP2C9 genotype influence warfarin sensitivity and dose requirements (PMID 20653669).
Recommendation: Keep vitamin K intake consistent and coordinate any vitamin K supplement with the prescriber if taking warfarin or another vitamin K antagonist.
Vitamin D3 increases calcium absorption, while K2 activates osteocalcin and matrix GLA protein to direct calcium into bones and away from arteries.
Recommendation: Take together. K2 (MK-7 100-200mcg) is recommended whenever supplementing D3 above 2000 IU.
K1 primarily supports coagulation while K2 (MK-7) directs calcium to bones. Complementary roles in vitamin K metabolism.
Recommendation: Both forms are beneficial. K2 (MK-7) has a longer half-life and better extrahepatic distribution than K1.
K2 activates osteocalcin to direct calcium to bones and matrix GLA protein to prevent arterial calcification. Essential when supplementing calcium.
Recommendation: Always take K2 (MK-7, 100-200mcg) when supplementing calcium to ensure proper calcium deposition in bones, not arteries.
K2 (MK-7) is fat-soluble and absorption increases with dietary fat. Fish oil provides an excellent fat vehicle.
Recommendation: Take K2 with fish oil or a fat-containing meal for optimal absorption.
High-dose vitamin E may reduce K2-dependent protein carboxylation, potentially affecting both bone and cardiovascular K2 benefits.
Recommendation: Keep vitamin E at moderate doses (200 IU or less) when relying on K2 for bone and cardiovascular health.
K2 (MK-7) is fat-soluble and absorption increases with dietary fat. Fish oil provides an excellent fat vehicle.
Recommendation: Take K2 with fish oil triple strength or a fat-containing meal for optimal absorption.
K2 (MK-7) is fat-soluble and absorption increases with dietary fat. Fish oil provides an excellent fat vehicle.
Recommendation: Take K2 with krill oil or a fat-containing meal for optimal absorption.
MCT Oil provides a fat-containing carrier that can improve absorption of fat-soluble compounds like Vitamin K2.
Recommendation: Take Vitamin K2 with MCT Oil or another fat-containing meal to improve absorption.
Flaxseed Oil provides a fat-containing carrier that can improve absorption of fat-soluble compounds like Vitamin K2.
Recommendation: Take Vitamin K2 with Flaxseed Oil or another fat-containing meal to improve absorption.
Evening Primrose Oil provides a fat-containing carrier that can improve absorption of fat-soluble compounds like Vitamin K2.
Recommendation: Take Vitamin K2 with Evening Primrose Oil or another fat-containing meal to improve absorption.
Vitamin K2 supports directing calcium into bone and away from arteries, complementing strontium's bone-building action within a bone-health regimen.
Recommendation: Reasonable to include vitamin K2 alongside strontium for bone support, especially when calcium and vitamin D are also used. They do not compete for absorption.
Vitamins A and K2 contribute to bone and calcium handling alongside vitamin D, supporting balanced mineralization at nutritional intakes.
Recommendation: Reasonable to take together at nutritional doses; avoid high-dose preformed vitamin A (retinol), which at excess can adversely affect bone and antagonize vitamin D signaling.
Numbered references. Citations throughout the page link here.
16 RCTs with 6,425 subjects showed vitamin K2 significantly improved lumbar spine bone mineral density, particularly with combination therapy
In 9 RCTs with 6,853 participants, VK2 significantly increased lumbar BMD (WMD 2.17, 95% CI 1.59-2.76) and forearm BMD (WMD 1.57, 95% CI 1.15-1.99). No serious adverse events related to VK2 supplementation were reported.
Vitamin K combined with vitamin D significantly increased total BMD (pooled effect size 0.316, 95% CI 0.031-0.601) and significantly decreased undercarboxylated osteocalcin across 8 RCTs with 971 subjects.
Bladbjerg EM, Levy-Schousboe K, Frimodt-Møller M et al.. No Detectable Coagulation Activation After Vitamin K (MK-7) Supplementation in Patients on Dialysis With Functional Vitamin K Deficiency: A One-Year Randomized, Placebo-Controlled Study. Journal of renal nutrition : the official journal of the Council on Renal Nutrition of the National Kidney Foundation. 2024
Naiyarakseree N, Phannajit J, Naiyarakseree W et al.. Effect of Menaquinone-7 Supplementation on Arterial Stiffness in Chronic Hemodialysis Patients: A Multicenter Randomized Controlled Trial. Nutrients. 2023
Rønn SH, Harsløf T, Oei L et al.. The effect of vitamin MK-7 on bone mineral density and microarchitecture in postmenopausal women with osteopenia, a 3-year randomized, placebo-controlled clinical trial. Osteoporosis international : a journal established as result of cooperation between the European Foundation for Osteoporosis and the National Osteoporosis Foundation of the USA. 2021
De Vriese AS, Caluwé R, Pyfferoen L et al.. Multicenter Randomized Controlled Trial of Vitamin K Antagonist Replacement by Rivaroxaban with or without Vitamin K2 in Hemodialysis Patients with Atrial Fibrillation: the Valkyrie Study. Journal of the American Society of Nephrology : JASN. 2020
MK-7 prevented age-related deterioration of trabecular bone microarchitecture at the tibia in healthy postmenopausal women over 3 years
Menaquinone-7 increased carboxylated/undercarboxylated osteocalcin ratio dose-dependently; daily intake >=100 mcg suggested for optimal gamma-carboxylation
Caluwé R, Vandecasteele S, Van Vlem B et al.. Vitamin K2 supplementation in haemodialysis patients: a randomized dose-finding study. Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association. 2014
MK-7 supplementation significantly decreased age-related decline in bone mineral content and bone mineral density at femoral neck; also improved bone strength
Vitamin K2 deficiency may be responsible for the 'calcium paradox', low calcium in bone and accumulation in vessel walls; K2 activates both osteocalcin and MGP
Huang SH, Fang ST, Chen YC. Molecular Mechanism of Vitamin K2 Protection against Amyloid-β-Induced Cytotoxicity. Biomolecules. 2021
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