Vitamin K2 (MK-7) Effects on the Body
Yes, Vitamin K2 (MK-7) has significant biological activity, primarily activating vitamin K-dependent proteins that regulate bone mineralization, prevent vascular calcification, and may reduce inflammation, though current dietary guidelines lack specific K2 recommendations due to insufficient data. 1
Primary Biological Functions
Vitamin K2 serves as a cofactor for gamma-glutamylcarboxylase, converting undercarboxylated proteins into their active carboxylated forms. 2 This activation is essential for:
- Blood clotting: Carboxylates coagulation factors II, VII, IX, and X, making them functionally active 1
- Bone health: Activates osteocalcin, which facilitates calcium deposition in bones 3
- Cardiovascular protection: Activates matrix Gla protein (MGP), which prevents calcium deposition in arterial walls 3
Key Differences from Vitamin K1
MK-7 (K2) is absorbed more readily and has superior bioavailability compared to vitamin K1 (phylloquinone). 2 While K1 is found in leafy greens and primarily supports hepatic coagulation function, K2 demonstrates more robust extrahepatic activity in bones and blood vessels. 2
Clinical Evidence for Health Benefits
Bone Health
Vitamin K2 upregulates osteoprotegerin, which acts as a decoy receptor for RANK ligand (RANKL), thereby inhibiting bone resorption. 3 Level I and II evidence supports K2 use in osteoporosis, potentially rivaling bisphosphonate therapy without toxicity. 4
- Enhanced bone calcification demonstrated in animal models, particularly when combined with zinc 5
- Lower rates of low-energy fractures associated with better vitamin K status 6
Cardiovascular Health
Level II evidence supports vitamin K2 in preventing coronary calcification and reducing cardiovascular disease risk. 4 By activating MGP, K2 prevents vascular stiffness and improves endothelial function. 6, 3
Anti-Inflammatory Effects
Vitamin K status correlates with lower concentrations of inflammatory markers in vivo, potentially through suppression of NF-κB signal transduction. 1 K2 also suppresses proinflammatory mediators including IL-1α, IL-1β, and TNF-α. 3
Other Potential Benefits
Evidence suggests K2 may benefit:
- Cancer: Suppresses growth via cell-cycle arrest, autophagy, and apoptosis 3
- Diabetes: May improve insulin sensitivity 7
- Peripheral neuropathy: Clinical studies show amelioration with supplementation 3
- Brain health: Supports brain development and may benefit Alzheimer's disease 6, 3
Safety Profile
Vitamin K1 and K2 are not associated with toxicity. 1 MK-7 has a documented history of safe and effective use without adverse effects, making it suitable for supplementation in pregnant women, nursing mothers, and children. 6
Critical Clinical Caveat
Patients on warfarin or other anti-vitamin K drugs must maintain consistent vitamin K intake and avoid sudden major changes. 1 Vitamin K2 can overcome warfarin's effect by bypassing the warfarin-sensitive vitamin K epoxide reductase step. 1 Blood clotting tests require monitoring, and warfarin dosage adjustment is necessary if K2 supplementation begins. 1, 4
Dietary Sources
Fermented cheeses are a major source of vitamin K2, as bacterial cultures synthesize menaquinones during fermentation. 7 Full-fat dairy products and fermented dairy (yogurt, cheese) also provide K2. 7
Current Guideline Limitations
The adequate intake (AI) for vitamin K is established for K1 only (1 mcg/kg body weight per day per EFSA; 120 mcg for males, 90 mcg for females per IOM), due to lack of data for vitamin K2. 1 This represents a significant gap in nutritional guidance given K2's distinct biological activities.