Vitamin K2
Fat-Soluble VitaminDirects calcium to bones and away from arteries. Works synergistically with Vitamin D3. MK-7 form has longest half-life.
Evidence comparisons not yet run for these claims.
Expert Consensus
Evidence Summary
The research on Vitamin K2 spans several health domains, with the strongest and most consistent evidence focused on bone health, particularly in postmenopausal women. Multiple meta-analyses, systematic reviews, and RCTs collectively suggest that Vitamin K2 — especially in the form of menaquinone-7 (MK-7) — may help reduce bone loss, improve bone quality, and support skeletal health, often with greater effect when combined with Vitamin D and calcium. There is also emerging evidence for cardiovascular benefits, including improvements in arterial stiffness, though this area is less established. More preliminary evidence exists for applications in dermatology and symptom management such as nocturnal leg cramps.
Read full evidence summary →Top studies
Efficacy of vitamin K2 in the prevention and treatment of postmenopausal osteoporosis: A systematic review and meta-analysis of randomized controlled trials.
Efficacy of vitamin K2 in the prevention and treatment of postmenopausal osteoporosis: A systematic review and meta-analysis of randomized controlled trials.
The combination effect of vitamin K and vitamin D on human bone quality: a meta-analysis of randomized controlled trials.
The combination effect of vitamin K and vitamin D on human bone quality: a meta-analysis of randomized controlled trials.
Expert Mentions
All 15 mentions
“if it came down to one or two nutrients D3 and K2 would be up there methyl folate would be right at the absolute top of the chart for me”
D3 and K2 are among the most important nutrients, ranking at the top alongside methylfolate.
“I would add probably to that a vitamin D3 or K2 yeah on that if you're if you're missing the basics then nothing else matters”
Adding a vitamin D3 and K2 supplement to a basic supplement routine is recommended for people who are missing the basics.
Safety, interactions & who should avoid Vitamin K2
Vitamin K2 supplementation appears to be well-tolerated in the populations studied, with no major safety concerns flagged across the reviewed trials. However, individuals on anticoagulant medications such as warfarin should exercise caution, as Vitamin K can interfere with clotting-related drug mechanisms.
Vitamin K2 (MK-7) has a favorable safety profile at studied doses with no established tolerable upper intake level. However, it may interfere with anticoagulant medications such as warfarin. It is generally considered safe for most adults, but individuals on blood-thinning therapy should consult a healthcare provider before supplementing.
Who should avoid it
Individuals taking warfarin or other vitamin K antagonist anticoagulants should use caution and consult their physician, as K2 may counteract the drug's blood-thinning effects. Those with rare conditions involving vitamin K metabolism disorders should also seek medical guidance before supplementing.
Known interactions
- ·Warfarin (vitamin K antagonist anticoagulants): K2 may reduce anticoagulant efficacy, potentially altering INR levels
- ·Broad-spectrum antibiotics: may reduce gut bacterial production of menaquinones, altering vitamin K status
- ·Cholesterol-lowering bile acid sequestrants (e.g., cholestyramine): may reduce absorption of fat-soluble vitamins including K2
Pregnancy & breastfeeding
We don’t assign pregnancy-safety ratings. Many supplements lack adequate safety data in pregnancy and breastfeeding, and the absence of a warning here does not mean a supplement is safe to take. Don’t start, stop, or continue any supplement while pregnant or nursing without your OB-GYN or midwife.
Read: Supplements during pregnancy & breastfeeding →This is educational information only. Consult a healthcare provider before starting any supplement.
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Key findings
- ·Meta-analyses and systematic reviews support Vitamin K2 supplementation for reducing bone loss and improving bone mineral density in postmenopausal women, particularly when combined with Vitamin D.
- ·A 3-year RCT found that low-dose MK-7 supplementation helped decrease bone loss in healthy postmenopausal women, suggesting benefits even at modest doses over extended periods.
- ·RCTs in both healthy postmenopausal women and chronic hemodialysis patients found improvements in arterial stiffness with MK-7 supplementation, pointing to potential cardiovascular benefits.
Evidence gaps
- ·Most studies focus on postmenopausal women or specific patient populations such as hemodialysis patients, leaving gaps in evidence for men, younger adults, and diverse demographics.
- ·Optimal dosing, duration, and form of Vitamin K2 (e.g., MK-4 vs. MK-7) have not been firmly established, and no separate Recommended Daily Intake for K2 distinct from K1 has been widely adopted.
- ·Evidence for applications outside bone and cardiovascular health — such as dermatology, leg cramps, and aortic valve calcification — is limited to single or small trials and requires larger, well-powered studies before conclusions can be drawn.