Skip to content
DE
Vitamin

Vitamin K2

Vitamin K2 is a family of fat-soluble menaquinones, made by bacteria and found in fermented foods such as natto and cheese. With K1, it is a main natural form of vitamin K.

Also listed as Vitamin K-2, Vitamin K, Phylloquinone, Menaquinone

Bone & JointEssential HealthCardiovascularOrgan Function

What it is studied for

The strongest rated effects first. Bars show the size of the effect, the letter grades the evidence, and each rating lists the studies behind it.

Bone densityBone & JointStrongA3 studies
Essential HealthStrongA3 studies
Blood pressureCardiovascularSmallCNo linked study
Liver healthOrgan FunctionSmallCNo linked study
InflammationSmallCNo linked study
Cholesterol balanceCardiovascularSmallCNo linked study
Every rating with its studiesGrouped by health goal, with the publications behind each rating

What is vitamin K for?

Vitamin K helps activate proteins involved in blood clotting and bone metabolism. K1 and the K2 family are its main natural forms. 1

Why is K2 studied for bones?

Osteoporosis trials examine whether K2 changes bone density and fractures after menopause. Those outcomes need separate answers: a favorable scan result does not automatically mean fewer broken bones. 2

Who is at risk of deficiency?

Clinically important deficiency is rare in adults, but poor intestinal absorption and certain medicines can create a risk. Severe deficiency causes bleeding. 1

Key studies

The most recent publications linked to Vitamin K2's ratings.

Vitamin K2 in Health and Disease: A Clinical Perspective2024Efficacy of vitamin K2 in the prevention and treatment of postmenopausal osteoporosis: A systematic review and meta-analysis of randomized controlled trials2022The combination effect of vitamin K and vitamin D on human bone quality: a meta-analysis of randomized controlled trials.2020Quantifying dietary vitamin K and its link to cardiovascular health: a narrative review.2020Vitamin K as a Diet Supplement with Impact in Human Health: Current Evidence in Age-Related Diseases2020
All 6 studiesEvery publication linked to Vitamin K2

Why people take it

Essential Health20%
Immune Support19.5%
Bone & Joint14.4%
Energy13.9%
Longevity6.1%
Cardiovascular6%

SuppCo community snapshot, 2026-09-28. Reasons for use are not evidence that it works.

Questions people ask

Does a better bone-density result prove fewer fractures?

No. The K2 meta-analysis found improved lumbar density, while its overall fracture analysis was not significant. 2

Should everyone combine vitamins D and K?

Combination trials found favorable bone measurements, but cannot establish that everyone taking D needs extra K. 3

How much vitamin K does DGE recommend?

For ages 19 to under 51, the estimated adequate intake is 70 µg daily for men and 60 µg for women. 4

Can I change my K supplement while taking warfarin?

Sudden changes can alter anticoagulation; the treating clinician needs to be involved. 1

Is K2 an established treatment for artery calcification?

No. The biological rationale remains under study, and clinical results are inconclusive. 1

Sources

  1. Vitamin K: Fact Sheet for Health Professionals NIH Office of Dietary Supplements

Further reading

Illustration for Vitamin K2.GuideVitamin K: blood levels, clotting and bone healthK1, K2 and functional markers explained clearly, with the limits of lab tests and important interactions.Read the article