What is vitamin K2?
Menaquinone (MK-7 and others)
Vitamin K2 is a form of vitamin K that activates proteins which pull calcium into bones and help keep it out of artery walls.
If vitamin D is the truck bringing calcium into town, K2 is the traffic controller that sends each delivery to the right address: bones yes, arteries no.
Why it matters for aging
Vitamin K comes in two main forms. K1, from leafy greens, mainly helps blood clot. K2 comes from fermented foods, especially natto (fermented soybeans), and in smaller amounts from aged cheese, egg yolks and some meats.
Because vitamin K affects blood clotting, people taking warfarin or similar blood thinners must not start K2 supplements without their doctor.
A common myth
Vitamin K2 is proven to clean calcium out of your arteries.
In a 2026 trial of people with heart disease, K2 modestly slowed new calcium buildup in heart arteries. Other trials found no clear effect, and none has shown fewer heart attacks yet.
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Updated Nov 9, 2026 · All terms