Vitamins & minerals
Vitamin K — K1 & K2
Names you may see: vitamin K1 K2 phylloquinone menaquinone MK4 MK7 MK-4 MK-7
The quick take
Vitamin K participates in normal blood clotting and the function of certain bone proteins.
A closer look
What forms will I see on a label?
K1 is phylloquinone; K2 includes menaquinones such as MK-4 and MK-7. These forms and their amounts differ.
Why people use it
People choose vitamin K for bone-health support, often alongside vitamin D. K2 products are also marketed for calcium-related cardiovascular goals.
These are common goals and marketing uses. The evidence section below explains what research supports.
What does the evidence tell us?
Vitamin K is essential, but evidence for preventing fractures or cardiovascular disease through routine supplementation remains uncertain.
What should I know before using it?
Vitamin K can substantially affect warfarin and similar anticoagulants. Keep intake consistent and discuss any supplement changes with the clinician managing treatment.
Sources & further reading
NIH Office of Dietary Supplements ↗
Content reviewed: September 30, 2026
General educational information. Follow the product label and seek individual advice when needed.