Can vitamin K2 help keep your bones strong?

Vitamin K2 may help keep spine bone density up in postmenopausal women. Fracture results are mixed, and artery studies so far are small.

Published October 2026

Short answer

Some trials show a modest spine density gain, but fracture benefit is not established, and the artery evidence is small and mixed. Evidence grade C (Limited). Meta-analyses and trials show spine density gains, but some well-run trials found none and fracture results are mixed; downgraded for inconsistency and because bone density is a surrogate marker.

Key takeaways

In a 2022 meta-analysis of 16 trials with 6,425 people, vitamin K2 was linked to better lumbar spine bone density [1].
A 12-month trial of 334 women in Norway found no difference in bone loss, while a three-year trial found slower loss at the spine [2][3].
Pooled fracture results were not clearly positive, and one analysis reached significance only after dropping one trial [1][4].
Higher rates of side effects were reported in some pooled analyses, but no serious side effects were linked to it [5].

The short version

Vitamin K2 may help keep bone density in the spine from falling in postmenopausal women. Pooled trials show a modest gain at the lumbar spine [1][5]. Whether it prevents fractures is not settled, because the fracture results are mixed [1][4]. Trials on vitamin K2 and artery calcification are small and do not agree.

What the studies show

For bone density, a 2022 meta-analysis of 16 randomised trials with 6,425 people found a significant improvement in lumbar spine bone density [1]. A second 2022 meta-analysis of nine trials with 6,853 people found a larger lumbar bone density change with vitamin K2 (weighted mean difference 2.17, 95% confidence interval 1.59 to 2.76) [5].

Single trials are more mixed. A three-year trial of 244 postmenopausal women found that a vitamin K2 form called menaquinone-7 (MK-7) slowed the age-related decline in bone mineral content and density at the lumbar spine and femoral neck, though not at the total hip [3]. A 12-month trial of 334 women in Norway found no difference in bone loss at any site [2].

For fractures, a 2022 meta-analysis of six trials found no clear difference overall (risk ratio 0.96, P = 0.65). The result became significant only after excluding one trial with a heterogeneous result [1]. A 2019 review of menatetrenone, another form of vitamin K2, found a vertebral fracture risk ratio of 0.87 (0.64 to 1.20), which was not significant [4].

For arteries, a two-year trial in 180 people with coronary artery disease found that MK-7 slowed the rise in coronary calcium: the score reached a median of 184 units in the MK-7 group against 214 in the placebo group [6]. A two-year trial of 365 men with aortic valve calcification found no difference when MK-7 was taken with vitamin D [7].

The nuances

Many of the bone trials in these reviews tested menatetrenone, a form studied for years in Japan [5][4]. In one Chinese trial of 236 women with osteoporosis, menatetrenone and calcium at 500 mg a day gave no difference in spine density; the lumbar gains were 1.2% with menatetrenone and 2.2% with calcium [8].

In a 12-week trial of kidney transplant recipients, MK-7 prevented a rise in arterial stiffness but did not change calcification propensity [9]. In a 24-week trial in people on dialysis, the effect on arterial stiffness was not significant overall and only reached significance in people with diabetes [10].

For safety, one pooled analysis found higher rates of side effects with vitamin K2 (risk ratio 1.33, 1.11 to 1.59), with no serious side effects linked to it [5]. Another pooled analysis of menatetrenone found more adverse drug reactions (risk ratio 1.29, 1.07 to 1.56) [4]. Our searches did not find studies on the upper intake limit, pregnancy, or breastfeeding, so those remain open.

People taking warfarin should be cautious. A 2016 review of dietary vitamin K and warfarin found conflicting evidence, and it advised against restricting vitamin K-rich foods, but it excluded supplements [11].

What this means for you

If you are considering vitamin K2 for your bones, talk with a doctor first, especially if you take a blood thinner such as warfarin, have kidney disease, or are pregnant. The fracture evidence is not settled [1][4]. For the full picture of bone health, see the vitamin K2 topic page.

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Vitamin K2 — Vitamin K2 may help keep spine bone density up in postmenopausal women, but fracture results are mixed and the artery studies are small and do not agree.