Vitamin K2
Also known as: menaquinone, MK-7, menaquinone-7, MK-4, phylloquinone K2
Effective Dosage
240–720 mcg daily (studies used varying doses depending on indication)
What the Science Says
Vitamin K2 is a fat-soluble vitamin found naturally in fermented foods and some cheeses. It activates proteins like osteocalcin that help direct calcium into bones rather than soft tissues, making it relevant for bone health and potentially cardiovascular health. Clinical trials suggest it may improve bone turnover markers, reduce long COVID symptoms when combined with vitamin D3, and show some benefit in reducing hepatocellular carcinoma recurrence — though results across cardiovascular and muscle-recovery outcomes are inconsistent.
What It Doesn't Do
Won't reliably reduce inflammation in heart tissue — a large 24-month trial found no effect on epicardial fat or systemic inflammation markers. Doesn't meaningfully speed up muscle recovery or reduce soreness after hard workouts. No strong evidence it improves muscle strength on its own. Eating K2-rich cheese didn't outperform regular cheese for athletic performance in skiers.
Evidence-Based Benefits
Vitamin K2 (MK-7) activates osteocalcin and influences bone turnover markers, with Jarlsberg cheese studies showing increased osteocalcin and reduced bone resorption marker CTX in postmenopausal women and older men (PMID: 41768503). Combined K2/D3 supplementation showed improvement in Long COVID symptom scores, gut markers, and systemic inflammation in a randomized controlled trial (PMID: 39861434). A meta-analysis of 11 studies in hepatocellular carcinoma patients found vitamin K supplementation significantly reduced disease recurrence and mortality at 1, 2, and 3 years without increased adverse events (PMID: 41388930).
Moderate EvidenceEffective at: 240–720 mcg/day depending on indication; No single universally established dose from provided studies
Source: auto-research
Absorption & Bioavailability
Good — MK-7 form (menaquinone-7) has a long half-life and is well-absorbed; studies confirmed circulating MK-7 levels rose significantly after supplementation. Fat-soluble, so best taken with a meal containing fat.
Red Flags to Watch For
- Interacts with blood-thinning medications like warfarin — can reduce their effectiveness and increase clot risk; always consult a doctor if on anticoagulants
- Intramuscular vitamin K injections (not oral supplements) have been linked to serious skin reactions including sclerodermoid plaques and drug-induced anetoderma
- Most trials combine K2 with vitamin D3, making it hard to isolate K2's independent effects
- High-dose supplementation (720 mcg/day for 2 years) showed no cardiovascular benefit in a large RCT, despite being widely marketed for heart health
Products Containing Vitamin K2
See how Vitamin K2 is used in these analyzed products:
Research Sources
- PubMed
- NIH DSLD
This information is for educational purposes only and is not medical advice. Always consult a healthcare professional before starting any supplement regimen. Last updated: 2026-04-06