Conclusion: A recent systematic review of seven Japanese randomized controlled trials by Cockayne has also shown that supplementation with phytonadione (Vitamin K1) and menaquinone (Vitamin K2) , particularly menaquinone-4, is associated with increased BMD and reduced fracture incidence. To confirm these results, a larger well design RCT using fractures as the primary endpoint is clearly needed.
PubMed 18830045 ↗Vitamin K1
Based on 4 first-hand reports and 18 meta-analyses & systematic reviews in the medical literature. Ranked #1405 of 1,974 overall.
Of reports that state an outcome, 100% are positive.
What Vitamin K1 does, according to users
Of the people who reported each effect, the share who said it got better.
What the research says
Systematic reviews and meta-analyses from PubMed, with their published conclusions.
3+ meta-analyses or systematic reviews and 10+ randomized controlled trials in humans. The grade measures how much human research exists — read the conclusions below for what it found.
Conclusion: Also, subgroup analysis showed no potential effect of vitamin K supplementation on any outcome and omitting any articles did not affect the final results. We demonstrated that supplementation with vitamin K has no effect on anthropometrics indexes, CRP, glucose metabolism, and lipid profile factors except HOMA-IR.
PubMed 38282652 ↗Conclusion: There is sufficient evidence to support the effectiveness of a single intramuscular dose of vitamin K to prevent the classic form of HDN. With regard to late HDN and oral route, the results are inconclusive because the studies used biochemical indicators of effectiveness, which can not be correlated with the actual coagulation status of the newborn due to lack of scientific evidence.
PubMed 21111646 ↗Conclusion: When stratified by follow-up duration, the RR of fracture for dietary vitamin K intake was 0.76 (95% CI: 0.58-0.93) in studies with more than 10 years of follow-up. Our study suggests that higher dietary vitamin K intake may moderately decrease the risk of fractures.
PubMed 28445289 ↗Dosage people report
As stated by users — not a recommendation. Follow the label or your doctor.
Reported side effects
How often each side effect came up across all reports.
What users say
Verbatim quotes, shortened only — each links to the original discussion.
“500ug Vitamin K1”
“My multivitamin stack includes vitamin D, vitamin K1 and K2, vitamin B complex”
“K1: 1.5mg, daily”
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User data from public discussions; research from PubMed. Information only, not medical advice — talk to a doctor before starting, stopping or combining anything. Data updated October 2, 2026. How we rate