Supplement evidence

012 / 575Vitamin

Vitamin K

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The short answer

Preventing or treating deficiency and supporting normal blood clotting.

Evidence and scope: Established for an indicated use
This status does not grade the ingredient for every goal, outcome, or person.
Important limitation: Evidence does not establish routine supplementation as a lifespan intervention.
Before deciding: Intake must be kept consistent with warfarin and similar medicines.

01 / PRACTICAL GUIDE

Dose, absorption, and combinations

These are indication-specific reference or studied ranges—not a personalized prescription. Start with the objective, then check the form, label, medicines, and health conditions.

Reference range by objective

Meeting usual needs90 mcg/day women; 120 mcg/day men as adequate intake

Reference or studied range—not a personalized prescription. The product label or a clinician may specify a different dose.

Dose source ↗

More is not automatically better. A clinician or product label may specify a different amount.

Absorption / solubilityFat-soluble / lipid-based

Fat-soluble or lipid-based. Absorption generally improves with a meal containing fat.

How it is commonly taken

Take with a meal containing fat.

Do not combine casually

Do not change intake suddenly when using warfarin; keep intake consistent and coordinate with the prescriber.

Dose and use source ↗

Dose and use links lead to primary or official source material. Search links are discovery tools, not proof that every returned paper applies.

02 / EVIDENCE

What the research says

We keep supportive, mixed, negative, safety, and contextual findings together. The headline never replaces the underlying papers.

4research papers in this ledger

36unique primary studies represented

—unique participants represented

These are audited counts for this JIVANA collection, not search-result totals. Participants are counted once when multiple papers use the same cohort; review papers are not added again to participant totals.

Open the research timelineResearch timeline

Entries are ordered by publication year. A study period appears only when the source reports it.

2024

Does not support the tested claimPMID 38938724

Effects of Vitamin K2 and D Supplementation on Coronary Artery Disease in Men

The combination did not significantly reduce mean coronary-calcium progression. Subgroup and safety findings were hypothesis-generating and cannot isolate vitamin K2 from vitamin D.

Published: 2024Duration: 2 yearsn=304 participants

Study design and methods

Design: Multicenter, double-blind, randomized placebo-controlled trial
Population: 304 men, mean age 71, without prior ischemic heart disease in the coronary analysis
Intervention: Vitamin K2 720 μg/day plus vitamin D 25 μg/day versus placebo
Outcome: Coronary calcium and plaque progression; composite safety events

Funding or conflict note: Study tablets were provided by Kappa Bioscience and Orkla Care; funders reportedly had no role. The combined intervention and possible overlap are excluded from aggregate totals.

Open research record ↗

2023

Mixed or qualifiedPMID 37252246

Vitamin K supplementation and vascular calcification

Pooled surrogate measures favored slower coronary calcification and improved vitamin K status, but this did not establish fewer cardiovascular events and more rigorous trials are needed.

Published: 2023n=1,533 participants14 primary studies represented

Study design and methods

Design: Systematic review and meta-analysis of 14 randomized trials
Population: 1,533 adults across vascular-calcification trials, including cardiovascular and kidney-disease populations
Intervention: Vitamin K supplementation versus control
Outcome: Coronary and other calcification, vascular stiffness, vitamin K biomarkers, and serious adverse events

Funding or conflict note: The authors declared no commercial or financial conflict. Possible overlap with other vitamin K syntheses is excluded from aggregate totals.

Open research record ↗

2023

Does not support the tested claimPMID 37338608

The additive effect of vitamin K supplementation and bisphosphonate on fracture risk in post-menopausal osteoporosis

Neither K1 nor MK-4 added a clear bone-density or turnover-marker benefit to bisphosphonate, calcium, and/or vitamin D treatment; isolated hip-geometry findings were secondary.

Published: 2023Duration: 18 months

Study design and methods

Design: Randomized, placebo-controlled three-arm trial
Population: 105 postmenopausal women with osteoporosis and suboptimal vitamin K status
Intervention: Vitamin K1 1 mg/day, vitamin K2 (MK-4) 45 mg/day, or placebo alongside standard osteoporosis treatment
Outcome: Bone mineral density, hip geometry, and bone-turnover markers

Open research record ↗

2019

Mixed or qualifiedPMID 31076817

Effect of vitamin K on bone mineral density and fractures in adults

Vitamin K did not clearly improve bone density or vertebral fractures. A possible reduction in clinical fractures weakened when analysis was restricted to trials at low risk of bias.

Published: 201936 primary studies represented

Study design and methods

Design: Systematic review and meta-analysis of 36 randomized trials
Population: Adults, primarily postmenopausal women or people with osteoporosis
Intervention: Oral vitamin K formulations versus control
Outcome: Bone mineral density and clinical or vertebral fractures

Funding or conflict note: A 2020 correction adjusted pooled estimates after integrity concerns about one included study. The dossier uses the corrected, cautious interpretation. The abstract did not report a participant total, so participants are excluded from the aggregate total.

Open research record ↗

Unscreened discovery appendix—not evidence1,987 candidate publicationsSearch run: Aug 21, 2026

Complete for the displayed PubMed query at the search timestamp—not for all databases or every possible synonym. Candidates can be irrelevant, duplicate the same study, or report negative findings. They are never summed as evidence or participants until screened.

03 / SOURCES

Start with the source material

Official evidence overviewNIH Office of Dietary Supplements Live PubMed discovery searchNational Library of Medicine

The live search is for discovery only. Search-result counts change and are not included in the audited totals above.

Recent PubMed discovery recordsDirect links to the first 12 records returned by the reproducible search. These are discovery candidates—not reviewed summaries or a count of supportive findings.

04 / EXPERT CONTEXT

Expert context—not evidence

Expert positions are dated context—not scientific evidence. They never raise the evidence status or become consensus by repetition.

No direct, source-verified endorsement is currently recorded. Research authorship or discussion alone is not treated as endorsement.