Condition
    Moderate Evidence
    Effectiveness 2/5

    Vitamin K1 for Osteoporosis

    Despite the popular association between vitamin K and bone health, high-dose K1 supplementation did not improve bone mineral density in a four-year randomized trial.

    Overview

    Despite the popular association between vitamin K and bone health, high-dose K1 supplementation did not improve bone mineral density in a four-year randomized trial.

    Verdict

    Not supported

    The bone evidence people cite for "vitamin K" comes from K2 menaquinone trials; K1 itself has been tested at high dose and did not deliver.

    How It Works

    Phylloquinone carboxylates osteocalcin, but hepatic uptake dominates and circulating half-life is short, limiting delivery to bone relative to menaquinones.

    Dosing & Protocol

    Typical dose

    Recommended dose
    Not recommended as a bone intervention
    Expected timeframe
    Not applicable - no fracture or density benefit demonstrated

    Protocol

    form
    Not applicable
    duration
    Not applicable
    co factor
    The verdict is no. The ECKO randomised trial gave 5 mg/day of vitamin K1 to postmenopausal women with osteopenia for 2-4 years: bone mineral density was no different from placebo. Vitamin K1 is required for carboxylation of osteocalcin, which is why the hypothesis was attractive, but supplementation above dietary adequacy does not translate into density or fracture benefit. Note that vitamin K2 (particularly MK-4 at 45 mg/day in Japanese trials) is a separate question with different, though still contested, evidence. Adequate dietary vitamin K1 from green vegetables is worth having on general grounds.
    titration
    Not applicable
    starting dose
    Not applicable - vitamin K1 is not an osteoporosis treatment

    Evidence

    What the studies say

    The ECKO trial randomized 440 postmenopausal women with osteopenia to 5 mg/day of vitamin K1 or placebo for two years, with 261 continuing to four years. Bone mineral density at the lumbar spine and total hip did not differ from placebo at any timepoint. A post-hoc fracture signal favoured K1 but the trial was not powered for fractures and the finding has not been replicated. Undercarboxylated osteocalcin fell substantially, confirming the supplement was biologically active — it simply did not translate into density. This is a clean demonstration that a plausible biomarker mechanism can operate fully without producing the outcome. Menaquinone-4 at 45 mg/day and MK-7 at 180 mcg/day have shown more favourable, though still contested, results, likely because they persist in circulation far longer and reach extrahepatic tissue better. Adequate dietary K1 from greens remains sensible; supplementing it for bone is not supported.

    Effect of vitamin K on bone mineral density and fractures in adults: an updated systematic review and meta-analysis of randomised controlled trials

    Score: 10/10
    2019
    meta_analysis
    n=11112

    Mott A, Bradley T, Wright K +5 more

    No consistent effect of vitamin K on bone mineral density; fracture reductions were confined to lower-quality trials.

    View source

    Vitamin K and the prevention of fractures: systematic review and meta-analysis of randomized controlled trials

    Score: 7/10
    2006
    meta_analysis
    n=3000

    Cockayne S, Adamson J, Lanham-New S +3 more

    Vitamin K supplementation was associated with improved bone density in all but one trial.

    View source

    Vitamin K supplementation in postmenopausal women with osteopenia (ECKO trial): a randomized controlled trial

    Score: 9/10
    2008
    rct
    n=440

    Cheung AM, Tile L, Lee Y +3 more

    Daily 5 mg vitamin K1 did not protect against bone mineral density loss in postmenopausal women with osteopenia.

    View source

    Effect of vitamin K supplementation on bone loss in elderly men and women

    Score: 9/10
    2008
    rct
    n=452

    Booth SL, Dallal G, Shea MK +3 more

    Phylloquinone reduced undercarboxylated osteocalcin but produced no difference in bone mineral density.

    View source

    Three-year low-dose menaquinone-7 supplementation helps decrease bone loss in healthy postmenopausal women

    Score: 8/10
    2013
    rct
    n=244

    Knapen MH, Drummen NE, Smit E +2 more

    MK-7 improved vitamin K status, decreased age-related decline in lumbar spine and femoral neck bone mineral density and reduced vertebral height loss.

    View source

    Safety

    Caveats

    Osteoporosis has treatments that demonstrably cut fracture risk - bisphosphonates, denosumab, and anabolic agents such as teriparatide and romosozumab - alongside adequate calcium (1000-1200 mg/day), vitamin D, resistance and weight-bearing exercise, smoking cessation and falls prevention. Do not substitute vitamin K1 for these, particularly after a fragility fracture, where the risk of a second fracture is high and treatment is urgent. Safety ceiling and interaction: vitamin K directly antagonises warfarin - a 5 mg daily dose will substantially reduce the INR and cause treatment failure, thrombosis or stroke. Anyone on warfarin must keep vitamin K intake consistent and not start a supplement without their anticoagulation clinic. Vitamin K1 is otherwise low in toxicity, and normal dietary intake is safe in pregnancy; high-dose supplementation in pregnancy is not established.

    Less likely to help if

    Everyone, for osteoporosis outcomes.

    Medical Disclaimer

    The information provided on this website is for educational and informational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition or before starting any supplement regimen.

    Individual results may vary. The statements on this website have not been evaluated by the Food and Drug Administration. Products and information are not intended to diagnose, treat, cure, or prevent any disease.