PlainPill

Vitamin K1

Based on 4 first-hand reports and 18 meta-analyses & systematic reviews in the medical literature. Ranked #1405 of 1,974 overall.

14
User score
Mostly positive
25% positive0% mixed0% negative75% unclear

Of reports that state an outcome, 100% are positive.

Clinical research
AStrong research base
18
meta-analyses
87
RCTs
1,491
papers

What Vitamin K1 does, according to users

Of the people who reported each effect, the share who said it got better.

No specific effects reported yet.
betterno changeworse

What the research says

Systematic reviews and meta-analyses from PubMed, with their published conclusions.

AStrong research base

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.

Clin Calcium · 2008 · Meta-analysis / systematic review
[Vitamin K2]

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 ↗
J Nutr Sci · 2024 · Meta-analysis / systematic review
The effect of vitamin K supplementation on cardiovascular risk factors: a systematic review and meta-analysis

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 ↗
Farm Hosp · 2011 · Meta-analysis / systematic review
[Prophylactic vitamin K for vitamin K deficiency bleeding of the newborn]

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 ↗
Medicine (Baltimore) · 2017 · Meta-analysis / systematic review
Vitamin K intake and the risk of fractures: A meta-analysis

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.

500ugsplit into 4 doses
1.5 mgdaily

Reported side effects

How often each side effect came up across all reports.

No side effects reported so far.

What users say

Verbatim quotes, shortened only — each links to the original discussion.

“500ug Vitamin K1”
Source discussion ↗
“My multivitamin stack includes vitamin D, vitamin K1 and K2, vitamin B complex”
Source discussion ↗
“K1: 1.5mg, daily”
Source discussion ↗
Top discussions (3)

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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