Vitamin K2
TL;DR
Vitamin that 'directs' calcium into bones and away from arteries
Moderate evidence for reducing arterial calcification and heart disease
Essential partner to Vitamin D for cardiovascular safety
Found in fermented foods like Natto and certain cheeses
Excellent safety; interacts with Warfarin
Cost: ~$5-10/month
Best for: Heart health, bone density, those taking high-dose Vitamin D
What it is
Vitamin K2 (specifically the MK-7 form) is the 'traffic cop' for calcium. While Vitamin D helps you absorb calcium, K2 activates proteins (like Osteocalcin and Matrix Gla Protein) that tell that calcium to go into your bones and teeth rather than your heart valves and arteries.
Without enough K2, high-dose Vitamin D and Calcium can actually contribute to 'calcification' of the soft tissues—a major driver of heart disease and kidney stones. K2 is mostly missing from the modern Western diet.
What the research says
K2 is all about 'vascular flexibility.' The Rotterdam Study. A massive observational study found that those with the highest K2 intake had a 57% lower risk of dying from heart disease. Arterial Stiffness. Clinical trials (like those by Vermeer et al.) show that MK-7 supplementation can significantly reduce arterial stiffness in postmenopausal women. Verdict. It is the ultimate 'insurance' for a healthy cardiovascular system.
Vitamin K2 on Amazon
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Safety
Extremely safe. There is no known toxicity level. However, because it is involved in blood clotting, it is the only vitamin with a major interaction with Warfarin.
Interactions
- Warfarin (Coumadin): K2 can completely neutralize the effect of this drug. Do not take K2 if you are on Warfarin without strict medical supervision.
Dosing
Standard Dose: 100-200 mcg daily as MK-7. Timing: Take with a fat-containing meal. Form: MK-7 is much more effective than MK-4 due to its longer half-life in the body.
Cost
Affordable. $5-10 per month.
The bottom line
Vitamin K2 is the missing link in heart and bone health. If you are taking Vitamin D or concern yourself with 'plaque,' K2 is non-negotiable.
Sources for this page include published meta-analyses, systematic reviews, and NIH dietary supplement fact sheets. All claims reflect the evidence as of early 2026.
This is not medical advice. Consult your healthcare provider before starting any supplement, especially if you take medications.