Vitamin K1 vs K2 (MK-7): What the Trials Show | Dose Track
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Vitamin K1 vs vitamin K2: what is the difference?

Half-life · Bone trials · Arteries · Warfarin

Short answer: K1 comes mainly from leafy greens; K2 (menaquinones) from fermented and animal foods.1 In a head-to-head study, both were absorbed well, but MK-7 lasted much longer in the blood and built up 7 to 8 times higher.2 Bone trials are mixed for both.34 Both matter for anyone on warfarin.1

How do vitamin K1 and K2 compare side by side?

From the NIH fact sheet and the human trials cited. Amounts are study protocols, not advice.
Vitamin K1 (phylloquinone)Vitamin K2 (MK-7)
Food sourcesMainly green leafy vegetables; the main dietary form1Modest amounts in animal and fermented foods; also made by gut bacteria1
Absorption and half-lifeAbsorbed well, peak at 4 hours, shorter half-life2Absorbed well, peak at 4 hours, very long half-life, builds up 7 to 8 times higher2
Bone trials5 mg a day for 2 to 4 years: no effect on bone density; fewer fractures, but the trial was not built to test that3180 mcg a day for 3 years: less bone loss at spine and hip neck;5 360 mcg a day for 1 year: no effect4
Artery calcium500 mcg a day for 3 years: no overall effect; slower progression in a subgroup6Not tested in the sources checked
WarfarinCan interact with warfarin and other blood thinners150 mcg a day or more may interfere with warfarin in a meaningful way2

Reviewed . Half-life figures are shown only where the value Dose Track uses agrees with the cited source.

What did the head-to-head study find?

In healthy volunteers, K1 and MK-7 were both absorbed well and peaked about 4 hours after intake. MK-7 stayed in the blood far longer, so levels were steadier and rose 7 to 8 times higher with daily use, and it activated a bone protein (osteocalcin) more fully. The authors warned that 50 mcg a day or more of MK-7 may interfere with warfarin.2

What did the bone and heart trials find?

K1. In 440 postmenopausal women with low bone density, 5 mg a day did not slow bone loss over 2 to 4 years. Fewer had fractures (9 vs 20), but the trial was not designed to test fractures.3 In 388 older adults, 500 mcg a day for 3 years did not slow artery calcium overall; it did in those who already had some calcium.6

K2 (MK-7). In 244 postmenopausal women, 180 mcg a day for 3 years slowed bone loss at the spine and hip neck, but not the total hip.5 In 334 early menopausal women, 360 mcg a day for 1 year did not change bone loss.4

So which one?

MK-7 lasts longer in the blood, which is the clearest difference. Neither form has consistent bone results, and no trial compared them on fractures. Vitamin K has no upper limit, but it interacts with warfarin.1 This is general information, not personal advice. More detail: the Vitamin K1 (Phylloquinone) and Vitamin K2 (MK-7) guides.

This page summarizes labels and published studies. It is not personalized medical advice; confirm any dose or change with your prescriber.
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Frequently asked questions

Is vitamin K2 better than K1?+
MK-7 lasts much longer in the blood than K1 and builds up higher.2 Bone trials are mixed for both, and no trial compared them on fractures.
Does vitamin K2 help bones?+
One 3-year trial found less bone loss;5 a 1-year trial found no effect.4
Can I take vitamin K on warfarin?+
Vitamin K interacts with warfarin, and MK-7 at 50 mcg a day or more may interfere with it. Talk to your prescriber.12
Can I track vitamin K in Dose Track?+
Yes. Log it with micrograms and reminders, and add notes.

Sources

  1. NIH Office of Dietary Supplements. Vitamin K fact sheet for health professionals (updated October 22, 2026).
  2. Schurgers LJ, et al. Vitamin K-containing dietary supplements: comparison of synthetic vitamin K1 and natto-derived menaquinone-7. Blood. 2007;109(8):3279-83.
  3. Cheung AM, et al. Vitamin K supplementation in postmenopausal women with osteopenia (ECKO trial): a randomized controlled trial. PLoS Med. 2008;5(10):e196.
  4. Emaus N, et al. Vitamin K2 supplementation does not influence bone loss in early menopausal women: a randomised double-blind placebo-controlled trial. Osteoporos Int. 2010;21(10):1731-40.
  5. Knapen MH, et al. Three-year low-dose menaquinone-7 supplementation helps decrease bone loss in healthy postmenopausal women. Osteoporos Int. 2013;24(9):2499-507.
  6. Shea MK, et al. Vitamin K supplementation and progression of coronary artery calcium in older men and women. Am J Clin Nutr. 2009;89(6):1799-807.

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