Vitamin K activates proteins for blood clotting and bone. K1 comes from leafy greens; K2 (MK-7) from fermented foods and supplements. Official values exist only for K1.
These are doses tested in research, not personal advice. Some exceed the upper limit because they were short courses or given under medical care.
Moderate evidenceModerate: smaller trials, mixed results or official guidance.Based on 1 randomised trial. 1 finding disagrees.How grades work
Slow bone loss after menopause
180 µg a day
244 healthy postmenopausal women took 180 µg MK-7 a day for 3 years. Bone density loss at the spine and hip neck was smaller than with placebo, and the effect showed only after 2 to 3 years. Industry-funded.
A Danish trial gave 375 µg MK-7 a day for 12 months to 142 women with osteopenia: bone density did not differ from placebo, only some bone structure measures at the shin.
Why: MK-7 stays in the blood much longer than MK-4, so a small once-a-day dose works. Long-term bone trials used about 180 µg MK-7.
Alternatives: MK-4 trials used milligram doses several times a day. At supplement doses it barely registers: in healthy women, 420 µg MK-4 was undetectable in blood at every time point, while the same dose of MK-7 was still measurable 48 hours later. K1 is what EFSA values are based on and is plentiful in leafy greens.
Vitamin DWeak evidenceWeak: one small trial, pilot data or results that conflict.Based on 1 meta-analysis.How grades work
Often sold together. A meta-analysis of 8 trials (971 people) found vitamin K plus vitamin D raised bone density a little more than no treatment, especially with K2 under 500 µg a day. The effect was small.