Does vitamin K help protect against osteoporosis?

Probably not, at the doses people buy. A 2019 meta-analysis of 36 randomized trials in people after menopause or with osteoporosis concluded there is no evidence that vitamin K affects bone density or vertebral fractures. Clinical fractures were less likely, an odds ratio of 0.72, but in the trials at low risk of bias that became 0.76 with an interval from 0.58 to 1.01, which no longer rules out no effect. The authors call the evidence insufficient to confirm it, and finds too few trials to say anything for other groups.

Unsettled. Fewer fractures is possible and unproven. The signal comes mostly from trials with design problems and weakens when they are set aside. No abstract here gives the absolute number of fractures avoided.

Fracture risk with vitamin K, ratio against control or lowest intake

Randomized trialsObservational data

The top four rows are randomized trials, the bottom two are observational and cannot show cause. The abstracts give ratios only, so the absolute number of fractures avoided is not known. Sources: cards ev-vkbd-01, ev-vkbd-03, ev-vkbd-13 and ev-vkbd-14 below.

What the trials found

Ordinary supplement doses in Western trials

These are the trials closest to what is sold in a pharmacy, and three of four found nothing. In 452 adults aged 60 to 80 who were getting enough calcium and vitamin D, 500 micrograms of vitamin K1 a day for 3 years did not change bone density at the spine or hip, a dose the authors call attainable from diet. In the ECKO trial, 440 women with osteopenia after menopause took 5 mg of vitamin K1 a day and lost bone at the same rate as placebo over 2 to 4 years. They had fewer clinical fractures, 9 against 20, but that was a secondary outcome with few events. In 142 Danish women with osteopenia, 375 micrograms of MK-7 a day on top of calcium and vitamin D did not slow bone loss at any site over 3 years.

The exception is a Dutch trial of 244 healthy women after menopause. Over 3 years, 180 micrograms of MK-7 a day slowed the decline in bone density at the lumbar spine and femoral neck, and did nothing at the total hip. The abstract gives no effect size. A higher dose in the Danish trial, in women with osteopenia, found no effect.

Menatetrenone, a high-dose drug

Much of the positive evidence comes from menatetrenone, a form of vitamin K2 given at 45 mg a day. In Japan and other parts of Asia this is used as a treatment for osteoporosis, hundreds of times dietary intake. A 2019 meta-analysis of 18 trials in 8,882 patients found it raised lumbar bone density by 0.05 g/cm2 against placebo, from 5 trials in 658 people. Vertebral fractures fell by a ratio of 0.87, which was not significant. A 2022 meta-analysis of 9 trials in 6,853 women with osteoporosis after menopause, mostly menatetrenone, found lumbar density 2.17 percent and forearm density 1.57 percent higher. A second 2022 meta-analysis of 16 trials in 6,425 women found better spine density and no difference in fractures, a ratio of 0.96. Fractures fell only after the authors removed one study.

A UK Health Technology Assessment review found the four open-label Japanese trials poorly reported, and the largest, the Osteoporosis Fracture study, found no reduction in vertebral fractures.

Vitamin K in food

Observational data link more vitamin K1 in the diet with fewer fractures. Across 5 studies of 80,982 people, the highest intake went with a 22 percent lower risk, a ratio of 0.78. A 2026 dose-response analysis of 6 studies in 93,776 people found only a trend, 0.83 with an interval reaching 1.01. Vitamin K1 comes with leafy vegetables and a better diet overall, so these figures cannot separate the vitamin from the eater.

Who should be careful

Not for everyone. If you take warfarin, phenprocoumon, acenocoumarol or tioclomarol, do not start vitamin K pills for your bones without the doctor who manages your anticoagulant. The NIH Office of Dietary Supplements calls the interaction serious and potentially dangerous. Big changes in how much leafy green food you eat matter for the same reason.

The drug dose has side effects. In the menatetrenone meta-analysis adverse events were more common than on placebo, a ratio of 1.47, and so were adverse drug reactions, 1.29, with no rise in serious events. The 2022 meta-analysis of vitamin K2 also found more adverse reactions and no serious ones. People on dialysis are a separate case. In a 2-year trial of 123 dialysis patients, 360 micrograms of MK-7 a day prevented a fall in spine density but sped up bone loss at the forearm near the wrist, and the authors do not support it for bone in dialysis.

What expert bodies say

The EU and the US treat vitamin K differently. The EU register authorizes the claim that vitamin K contributes to the maintenance of normal bones, which is a claim about having enough and says nothing about preventing osteoporosis. NIH ODS states that the FDA has not authorized a health claim for vitamin K in the United States. We found no NICE or WHO position on vitamin K for osteoporosis.

How we searched

Searched: a local copy of PubMed, queried on 7 October 2026 for vitamin K1, K2, menaquinone, MK-7 and menatetrenone with bone density, osteoporosis, fracture and bone loss (more than 60 records, 28 of them reviews), and for randomized trials of K1 and MK-7 with bone density or fracture (21). We also searched the NIH ODS fact sheet and the EU claims register, and ran a web search for reviews from 2025, which found nothing newer than the local copy. Ten of the twelve included papers were checked against Retraction Watch, and none was retracted.

Included: five systematic reviews of randomized trials, four of them meta-analyses, five randomized trials, two meta-analyses of observational studies, three NIH ODS statements and one EU register entry.

Excluded: a 2006 meta-analysis that now carries an expression of concern because it cites retracted trials, two retracted papers, a 2024 meta-analysis whose abstract gives only p-values, reviews of bone turnover markers alone, reviews of anticoagulant drugs rather than vitamin K, and a 6-month trial in 14 women.

What we read: abstracts, and the fact sheet and register text.

What we could not get: the full text of the 2019 meta-analysis of 36 trials, so its forest plots and participant numbers were not read. Vitamin K has no upper intake level in the NIH fact sheet or from EFSA.

What would change this answer

A large placebo-controlled trial outside Japan with fracture as the main outcome. We found none in the corpus or on the web.
A second trial of MK-7 at the Dutch dose in healthy women, to settle whether that result or the Danish one holds.
Better reporting of the menatetrenone trials, which carry most of the positive bone density results.

The rest of the nutrient, in one place. Vitamin K: the nutrient whose most useful fact is about a medicine → What it does, how much you need, who runs short, and what too much does, with the evidence level shown on every line.

The full guide

Vitamin K: the nutrient whose most useful fact is about a medicine

The same question for other foods (bone density)

Sources

ev-vkbd-01 · Meta-analysis or systematic review · systematic review and meta-analysis of randomized controlled trials · n = 36 studies
For post-menopausal or osteoporotic patients, meta-analysis showed that the odds of any clinical fracture were lower for vitamin K compared to controls (OR, 0.72, 95%CI 0.55 to 0.95). Restricting the analysis to low risk of bias trials reduced the OR to 0.76 (95%CI, 0.58 to 1.01). There was no difference in vertebral fractures between the groups (OR 0.96, 95%CI 0.83 to 1.11).
Who: post-menopausal or osteoporotic adults in RCTs of oral vitamin K
Effect: clinical fracture OR 0.72 (0.55 to 0.95); low risk of bias only OR 0.76 (0.58 to 1.01); vertebral fracture OR 0.96 (0.83 to 1.11)
Certainty: Update written because earlier evidence integrity was questioned; number of participants not in the abstract.
Osteoporos Int, 2019 · checked 2026-10-07 · we read the abstract
ev-vkbd-02 · Meta-analysis or systematic review · systematic review and meta-analysis of randomized controlled trials · n = 36 studies
For post-menopausal or osteoporotic patients, there is no evidence that vitamin K affects bone mineral density or vertebral fractures; it may reduce clinical fractures; however, the evidence is insufficient to confirm this. There are too few trials to draw conclusions for other patient groups.
Who: post-menopausal or osteoporotic adults; other adult groups
Effect: lumbar spine BMD +1.63% at 2 years (0.10 to 3.16) shrinking to non-significant without high risk of bias trials
Certainty: Authors' conclusion; sensitivity analysis drives it.
Osteoporos Int, 2019 · checked 2026-10-07 · we read the abstract
ev-vkbd-03 · Meta-analysis or systematic review · systematic review and meta-analysis of randomized controlled trials · n = 8882
Pooled analyses showed that menatetrenone was more effective than placebo in improving lumbar bone mineral density (BMD) (five studies, N = 658, MD = 0.05 g/cm2, 95% CI 0.01 to 0.09 g/cm2) and decreasing ucOC/OC (two studies, N = 75, MD = - 21.78%, 95% CI - 33.68 to - 9.87%). Compared with placebo, menatetrenone was associated with a nonsignificantly decreased risk of vertebral fracture (five studies, N = 5508, RR = 0.87, 95% CI 0.64 to 1.20).
Who: patients with osteoporosis in RCTs of menatetrenone
Effect: lumbar BMD MD 0.05 g/cm2 (0.01 to 0.09), 5 studies, N = 658; vertebral fracture RR 0.87 (0.64 to 1.20), 5 studies, N = 5508
Certainty: Includes Chinese-language databases; fracture benefit uncertain by the authors' own words.
Osteoporos Int, 2019 · checked 2026-10-07 · we read the abstract
ev-vkbd-04 · Meta-analysis or systematic review · systematic review and meta-analysis of randomized controlled trials · n = 6102
Furthermore, compared with placebo, menatetrenone significantly increased the incidence of adverse events (AEs) (two studies, N = 1949, RR = 1.47, 95% CI 1.07 to 2.02) and adverse drug reactions (four studies, N = 6102, RR = 1.29, 95% CI 1.07 to 1.56). However, no significant difference in the incidence of serious AEs was found between menatetrenone and placebo.
Who: patients with osteoporosis in RCTs of menatetrenone
Effect: adverse events RR 1.47 (1.07 to 2.02), 2 studies, N = 1949; adverse drug reactions RR 1.29 (1.07 to 1.56), 4 studies, N = 6102
Certainty: Drug dose of 45 mg/day, far above food intake.
Osteoporos Int, 2019 · checked 2026-10-07 · we read the abstract
ev-vkbd-05 · Meta-analysis or systematic review · systematic review and meta-analysis of randomized controlled trials · n = 6853
Nine RCTs with 6853 participants met the inclusion criteria. Vitamin K2 was associated with a significantly increased percentage change of lumbar BMD and forearm BMD (WMD 2.17, 95% CI [1.59-2.76] and WMD 1.57, 95% CI [1.15-1.99]).
Who: postmenopausal women with osteoporosis in RCTs of vitamin K2
Effect: lumbar BMD WMD 2.17 (1.59 to 2.76); forearm BMD WMD 1.57 (1.15 to 1.99); adverse reactions RR 1.33 (1.11 to 1.59), no serious events
Certainty: Trials mostly Japanese menatetrenone; no fracture pooled estimate in the abstract.
J Bone Miner Metab, 2022 · checked 2026-10-07 · we read the abstract
ev-vkbd-06 · Meta-analysis or systematic review · systematic review and meta-analysis of randomized controlled trials · n = 6425
The overall effect test of the six RCTs showed no significant difference in fracture incidence between the two groups (RR=0.96, P=0.65). However, after excluding one heterogeneous study, the overall effect test showed a significant reduction in fracture incidence with VK2 (RR = 0.43, P = 0.01).
Who: postmenopausal women in RCTs of vitamin K2
Effect: lumbar spine BMD improved (P = 0.006, 10 studies); fractures RR 0.96 (P = 0.65, 6 RCTs); RR 0.43 after excluding one heterogeneous study
Certainty: Post hoc exclusion drives the positive fracture result.
Front Public Health, 2022 · checked 2026-10-07 · we read the abstract
ev-vkbd-07 · Meta-analysis or systematic review · systematic review and economic evaluation of randomized controlled trials · n = 5 trials
The smaller menatetrenone trials found that menatetrenone was associated with a reduced risk of morphometric vertebral fractures relative to no treatment or calcium; however, the larger Osteoporosis Fracture (OF) study found no evidence of a reduction in vertebral fracture risk.
Who: postmenopausal women with osteoporosis or osteopenia in 5 trials
Effect: menatetrenone: smaller trials favorable, larger OF study no reduction in vertebral fracture; ECKO phylloquinone clinical fractures RR 0.46 (0.22 to 0.99)
Certainty: Search to 2009.
Health Technol Assess, 2009 · checked 2026-10-07 · we read the abstract
ev-vkbd-08 · Randomized controlled trial(s) · randomized placebo-controlled double-blind trial, 2 to 4 years · n = 440
There were no significant differences in changes in BMD at any site between the two groups over the 2- to 4-y period.
Who: postmenopausal women with osteopenia, vitamin D replete
Effect: lumbar spine BMD difference -0.06% (-0.67 to 0.54), total hip 0.19% (-0.37 to 0.75); clinical fractures 9 vs 20 (p = 0.04)
Certainty: Fractures were a secondary outcome with few events; 5 mg is far above diet.
PLoS Med, 2008 · checked 2026-10-07 · we read the abstract
ev-vkbd-09 · Randomized controlled trial(s) · randomized double-blind controlled trial, 3 years · n = 452
Phylloquinone supplementation in a dose attainable in the diet does not confer any additional benefit for bone health at the spine or hip when taken with recommended amounts of calcium and vitamin D.
Who: men and women aged 60-80 years, calcium and vitamin D replete
Effect: no difference in BMD change at femoral neck, spine or total body
Certainty: Dose attainable from diet; 401 completed.
J Clin Endocrinol Metab, 2008 · checked 2026-10-07 · we read the abstract
ev-vkbd-10 · Randomized controlled trial(s) · randomized placebo-controlled trial, 3 years · n = 244
MK-7 intake significantly improved vitamin K status and decreased the age-related decline in BMC and BMD at the lumbar spine and femoral neck, but not at the total hip.
Who: healthy postmenopausal women
Effect: smaller decline in BMC and BMD at lumbar spine and femoral neck; no effect at total hip
Certainty: Effect size not in the abstract; industry co-funding listed as non-US government support.
Osteoporos Int, 2013 · checked 2026-10-07 · we read the abstract
ev-vkbd-11 · Randomized controlled trial(s) · randomized placebo-controlled double-blind trial, 3 years · n = 142
After 3 years, aBMD decreased at all sites without differences between the MK-7 and placebo-treated women (p > 0.09).
Who: postmenopausal women with osteopenia on vitamin D3 38 mcg and calcium 800 mg
Effect: aBMD fell at all sites without group differences (p > 0.09)
Certainty: Higher MK-7 dose than the Dutch trial with the opposite result.
Osteoporos Int, 2021 · checked 2026-10-07 · we read the abstract
ev-vkbd-12 · Randomized controlled trial(s) · multicentre randomized double-blind placebo-controlled trial, 2 years · n = 123
In aggregate, our findings do not support MK-7 supplementation to preserve bone in patients on dialysis.
Who: patients on chronic dialysis
Effect: 1/3 distal radius BMD MD -0.023 g/cm2 (-0.039 to -0.008); lumbar spine MD 0.050 g/cm2 (0.015 to 0.085)
Certainty: Authors do not support MK-7 to preserve bone in dialysis.
Nephrol Dial Transplant, 2023 · checked 2026-10-07 · we read the abstract
ev-vkbd-13 · Observational data · meta-analysis of cohort and nested case-control studies · n = 80,982
We observed a statistically significant inverse association between dietary vitamin K intake and risk of fractures (highest vs. the lowest intake, RR = 0.78, 95% CI: 0.56-0.99; I = 59.2%, P for heterogeneity = .04).
Who: cohort and nested case-control participants, dietary phylloquinone
Effect: highest vs lowest RR 0.78 (0.56 to 0.99); per 50 mcg/day RR 0.97 (0.95 to 0.99)
Certainty: Observational; vitamin K intake tracks vegetable intake and overall diet quality.
Medicine (Baltimore), 2017 · checked 2026-10-07 · we read the abstract
ev-vkbd-14 · Observational data · systematic review and dose-response meta-analysis of observational studies, GRADE · n = 93,776
We found a trend towards a decreased risk of overall fractures with increased vitamin K consumption, with a risk ratio of 0.83 (95% CI, 0.68-1.01).
Who: participants of observational studies of dietary vitamin K
Effect: overall fractures RR 0.83 (0.68 to 1.01); hip fractures RR 0.76 (0.56 to 1.02); benefit up to 120 mcg/day
Certainty: Both intervals cross 1.
Curr Rheumatol Rev, 2026 · checked 2026-10-07 · we read the abstract
ev-vkbd-15 · Position of an expert body · fact sheet · n = —
In Japan and other parts of Asia, a pharmacological dose of MK-4 (45 mg) is used as a treatment for osteoporosis [5].
Who: general population; patients with osteoporosis in Japan and Asia
Effect: 45 mg MK-4 used as a drug in Asia
Certainty: Summary without own analysis.
NIH Office of Dietary Supplements, Vitamin K Fact Sheet for Health Professionals · checked 2026-10-07 · we read the section
ev-vkbd-16 · Position of an expert body · fact sheet · n = —
FDA has not authorized a health claim for vitamin K in the United States.
Who: general population
Effect: no authorized US health claim
Certainty: Contrasts with the authorized EU claim below.
NIH Office of Dietary Supplements, Vitamin K Fact Sheet for Health Professionals · checked 2026-10-07 · we read the section
ev-vkbd-17 · Position of an expert body · EU register entry · n = —
POL-HC-6524 Vitamin K Vitamin K contributes to the maintenance of normal bones Authorised
Who: EU food labeling
Effect: authorized health claim
Certainty: Maintenance claim for adequate intake; it does not say vitamin K prevents osteoporosis.
EU Register on nutrition and health claims, claim POL-HC-6524, snapshot 2026-09-21 · checked 2026-10-07 · we read the dataset
ev-vkbd-18 · Position of an expert body · fact sheet · n = —
Vitamin K can have a serious and potentially dangerous interaction with anticoagulants such as warfarin (Coumadin) as well as phenprocoumon, acenocoumarol, and tioclomarol, which are commonly used in some European countries [7,8].
Who: people taking warfarin, phenprocoumon, acenocoumarol or tioclomarol
Effect: vitamin K antagonizes these drugs
Certainty: Applies to supplements and to sudden changes in food intake.
NIH Office of Dietary Supplements, Vitamin K Fact Sheet for Health Professionals · checked 2026-10-07 · we read the section

How this page was made. Evidence was extracted from primary sources into cards, every number was re-checked against the source, and the text was written from those cards. Bioma Learn has no human medical reviewer at this time, and we say so rather than invent one. Methodology. This is information, not medical advice.