Vitamin K
also known as Vitamin K1, Phylloquinone, Phytonadione, Vitamin K2…
Supports blood clotting, bone formation and repair, calcium use, osteoporosis prevention, vascular health, liver function, glucose storage, infection resistance, and longevity.
Recommended daily intake
- Adult Men · 120 mcg (adequate intake)
- Adult Women · 90 mcg (adequate intake)
- K2 Separate Intake · no formal RDA for K2 specifically; clinical research uses 90-180 mcg of MK-7
Upper intake limit
Not formally established
Signs of deficiency
- Easy bruising and bleeding
- Heavy menstrual bleeding
- Blood in urine or stool
- Soft, fragile bones
- Calcification in arteries (suggested by some research as a sign of K2 inadequacy)
- Supports prothrombin production
- Supports normal blood clotting
- Supports bone formation
- Supports bone repair
- Supports calcium use in bones
- May help prevent osteoporosis
- May protect vascular health by reducing artery calcification
- Supports liver function
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Common questions
The adequate intake is 120 mcg for adult men and 90 mcg for adult women. There's no separate official amount for vitamin K2 specifically, though clinical research commonly uses 90 to 180 mcg of the MK-7 form.
Its best-known role is blood clotting, but it's also essential for bone formation and repair, helping your body use calcium correctly. There's also research suggesting it may help protect arteries from calcification.
No formal upper limit has been established. That's not the same as unlimited, though, particularly if you're on blood-thinning medication, since vitamin K directly affects clotting.
It's one of the nutrients tied to bone health, working alongside calcium and vitamin D to support bone formation and reduce fracture risk.