Claim deep dive·Moderate evidence·Updated July 13, 2026
Evidence review: Vitamin K2 supports bone density and reduces fracture risk
Especially well-supported for MK-4 at high pharmacologic doses (45 mg/day in Japanese trials). MK-7 at 180 mcg/day shows modest BMD preservation in postmenopausal women.
The bottom line.
The strongest studies.
Sorted by study tier (meta-analyses first, then RCTs, then reviews) and recency. Every entry links to PubMed by PMID, and every citation on this page points here.
Meta-analyses & systematic reviews
4- 1Efficacy of vitamin K2 in the prevention and treatment of postmenopausal osteoporosis: A systematic review and meta-analysis of randomized controlled trialsSource linkedPMIDMa ML et al. · Front Public Health · 2022
16 RCTs with 6,425 subjects showed vitamin K2 significantly improved lumbar spine bone mineral density, particularly with combination therapy
- 2Efficacy and safety of vitamin K2 for postmenopausal women with osteoporosis at a long-term follow-up: meta-analysis and systematic reviewSource linkedPMIDZhou M, Han S, Zhang W, Wu D · Journal of Bone and Mineral Metabolism · 2022
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.
- 3The combination effect of vitamin K and vitamin D on human bone quality: a meta-analysis of randomized controlled trialsSource linkedPMIDKuang X, Liu C, Guo X, Li K, Deng Q, Li D · Food & Function · 2020
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.
- 4Vitamin K and the prevention of fractures: systematic review and meta-analysis of randomized controlled trialsSource linkedPMIDCockayne S et al. · Arch Intern Med · 2006
Meta-analysis of Japanese MK-4 trials showed significant fracture reduction: OR 0.40 for vertebral, 0.23 for hip, and 0.19 for all nonvertebral fractures.
Randomized controlled trials
11- 5The effect of vitamin MK-7 on bone mineral density and microarchitecture in postmenopausal women with osteopenia, a 3-year randomized, placebo-controlled clinical trialSource linkedPMIDRønn SH, Harsløf T, Oei L et al. · Osteoporosis international : a journal established as result of cooperation between the European Foundation for Osteoporosis and the National Osteoporosis Foundation of the USA · 2021
- 6Vitamin K2 (menaquinone-7) prevents age-related deterioration of trabecular bone microarchitecture at the tibia in postmenopausal womenSource linkedPMIDKnapen MH et al. · Bone · 2016
MK-7 prevented age-related deterioration of trabecular bone microarchitecture at the tibia in healthy postmenopausal women over 3 years
- 7Low-Dose Daily Intake of Vitamin K(2) (Menaquinone-7) Improves Osteocalcin gamma-Carboxylation: A Double-Blind, Randomized Controlled TrialsSource linkedPMIDInaba N et al. · J Nutr Sci Vitaminol · 2015
Menaquinone-7 increased carboxylated/undercarboxylated osteocalcin ratio dose-dependently; daily intake >=100 mcg suggested for optimal gamma-carboxylation
- 8Low-dose vitamin K2 (MK-4) supplementation for 12 months improves bone metabolism and prevents forearm bone loss in postmenopausal Japanese womenSource linkedPMIDKoitaya N et al. · J Bone Miner Metab · 2014
Low-dose MK-4 (1.5 mg/day) for 12 months improved bone turnover markers and prevented forearm bone mineral density loss in postmenopausal women aged 50-65.
- 9Low-dose menaquinone-4 improves γ-carboxylation of osteocalcin in young males: a non-placebo-controlled dose-response studySource linkedPMIDNakamura E, Aoki M, Watanabe F et al. · Nutrition journal · 2014
- 10Three-year low-dose menaquinone-7 supplementation helps decrease bone loss in healthy postmenopausal womenSource linkedPMIDKnapen MH et al. · Osteoporos Int · 2013
MK-7 supplementation significantly decreased age-related decline in bone mineral content and bone mineral density at femoral neck; also improved bone strength
- 11The prevention of hip fracture with menatetrenone and risedronate plus calcium supplementation in elderly patients with Alzheimer disease: a randomized controlled trialSource linkedPMIDSato Y, Honda Y, Umeno K et al. · The Kurume medical journal · 2011
- 12Randomized controlled study on the prevention of osteoporotic fractures (OF study): a phase IV clinical study of 15-mg menatetrenone capsulesSource linkedPMIDInoue T, Fujita T, Kishimoto H et al. · Journal of bone and mineral metabolism · 2009
- 13Short-term menatetrenone therapy increases gamma-carboxylation of osteocalcin with a moderate increase of bone turnover in postmenopausal osteoporosis: a randomized prospective studySource linkedPMIDShiraki M, Itabashi A · Journal of bone and mineral metabolism · 2009
- 14Vitamin K2 (menatetrenone) effectively prevents fractures and sustains lumbar bone mineral density in osteoporosisSource linkedPMIDShiraki M et al. · J Bone Miner Res · 2000
In 241 osteoporotic patients over 24 months, 45 mg/day vitamin K2 significantly reduced clinical fracture incidence and maintained lumbar BMD compared to untreated controls.
- 15Vitamin K2 (menatetrenone) effectively prevents fractures and sustains lumbar bone mineral density in osteoporosisSource linkedPMIDShiraki M, Shiraki Y, Aoki C, Miura M · J Bone Miner Res · 2000
Vitamin K2 MK-4 at pharmacological doses significantly reduced fracture risk
Reviews & position papers
3- 16The biological responses of vitamin K2: A comprehensive reviewSource linkedPMIDHalder M et al. · Clin Nutr · 2023
Comprehensive review confirming MK-4's unique functions as SXR/PXR ligand, mitochondrial electron carrier, and transcriptional regulator, with roles beyond carboxylation in bone and brain.
- 17The Dual Role of Vitamin K2 in 'Bone-Vascular Crosstalk': Opposite Effects on Bone Loss and Vascular CalcificationSource linkedPMIDMandatori D et al. · Nutrients · 2021
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
- 18Vitamin K2 therapy for postmenopausal osteoporosisSource linkedPMIDIwamoto J, Takeda T, Sato Y · Nutrients · 2014
MK-4 at pharmacological doses is approved in Japan for osteoporosis treatment
What pushes back.
Caveats, null findings, and methodological limits that hold the tier where it is.
What the evidence supports.
What we recommend
180 to 360 mcg/day MK-7 alongside vitamin D and adequate calcium. The 45 mg/day MK-4 dose used in Japanese fracture trials is a pharmaceutical dose, not a standard supplement dose. 8,10
Tier criteria: /methodology/evidence-tiers. Sourcing standards: /methodology/interactions.
Common questions.
Quick answers drawn from the verdict, evidence, and recommendation above.
Does the evidence support the claim that vitamin k2 supports bone density and reduces fracture risk?
Especially well-supported for MK-4 at high pharmacologic doses (45 mg/day in Japanese trials). MK-7 at 180 mcg/day shows modest BMD preservation in postmenopausal women.
How strong is the evidence behind Vitamin K2 and Vitamin K2 MK-4 for this claim?
NutriStack rates this as Moderate evidence, meaning several aligned RCTs or one large RCT plus supporting reviews. Full tier criteria are at https://nutristackapp.com/methodology/evidence-tiers.
What contrary evidence or caveats apply?
Trials are concentrated in postmenopausal women; data in men is thinner. Many positive trials are Japanese and use dosing that western trials do not replicate.
What does NutriStack recommend?
180 to 360 mcg/day MK-7 alongside vitamin D and adequate calcium. The 45 mg/day MK-4 dose used in Japanese fracture trials is a pharmaceutical dose, not a standard supplement dose.
Selected claims, opened up
This is how NutriStack presents an evidence review.
Each published claim review shows its verdict, attached studies, contrary evidence, dose context, and limits. Coverage is selective rather than a claim that every database assertion has received the same review.