Vitamin K2 for Bone Health: Can It Help Postmenopausal Women?

observational-study PMID: 23525894

Quick Summary: A recent study found that taking a daily dose of vitamin K2 (specifically MK-7) for three years helped postmenopausal women maintain stronger bones and slow down bone loss, which is a common concern after menopause.

What The Research Found

This research showed that taking a daily vitamin K2 supplement (MK-7) helped postmenopausal women:

Keep their bones stronger: The study found that women taking MK-7 had less bone loss in their spine and hip area.

Improve Vitamin K levels: The supplement helped improve the body's use of vitamin K, which is important for bone health.

Potentially reduce fracture risk: The study suggested that MK-7 might help protect against fractures in the spine.

Study Details

Who was studied: 244 healthy women who had gone through menopause.

How long: The study lasted for 3 years.

What they took: Half the women took a daily capsule with 180 micrograms of MK-7 (a type of vitamin K2). The other half took a placebo (a dummy pill).

What This Means For You

If you're a postmenopausal woman, this research suggests that taking a vitamin K2 supplement (MK-7) might be a good idea to help keep your bones strong. Talk to your doctor about whether this is right for you. It's important to remember that this study focused on a specific type of vitamin K (K2, not K1) and that other things, like getting enough calcium and vitamin D, are also important for bone health.

Study Limitations

Who it applies to: This study only looked at postmenopausal women, so we don't know if the results would be the same for men or younger women.

Where it worked: The supplement seemed to help bones in the spine and hip area, but not necessarily in all parts of the body.

More research needed: While promising, more research is needed to confirm these findings and to see if vitamin K2 can actually prevent bone fractures.

Key Findings

This 3-year randomized controlled trial found that daily supplementation with 180 μg of menaquinone-7 (MK-7), a form of vitamin K2, significantly improved bone health in healthy postmenopausal women. MK-7 enhanced vitamin K status (reduced uncarboxylated osteocalcin [ucOC]/carboxylated osteocalcin [cOC] ratio), slowed age-related declines in bone mineral density (BMD) at the lumbar spine and femoral neck, and improved bone strength indices. It also reduced vertebral height loss in the lower thoracic region, suggesting protection against vertebral fractures. No significant effects were observed at the total hip.

Study Design

The study was a double-blind, placebo-controlled randomized trial (not observational, as initially noted) involving 244 healthy postmenopausal women. Participants were followed for 3 years, with measurements of BMD, bone strength, and vitamin K status (via ucOC/cOC ratio) taken at baseline and after 1, 2, and 3 years. Bone mineral density (BMD) and bone mineral content (BMC) were assessed using dual-energy X-ray absorptiometry (DXA), while vertebral fractures were evaluated via vertebral fracture assessment (VFA).

Dosage & Administration

The intervention group received 180 μg/day of MK-7 (as capsules) for 3 years. The placebo group received identical capsules without MK-7. Supplementation was administered daily, and compliance was monitored through capsule counts.

Results & Efficacy

Vitamin K Status: MK-7 significantly reduced the ucOC/cOC ratio (p < 0.001), indicating improved carboxylation of osteocalcin, a marker of bone health.
Bone Mineral Density:
Lumbar spine: MK-7 slowed BMD decline compared to placebo (p < 0.05).
Femoral neck: Significant preservation of BMD (p < 0.05).
Total hip: No significant effect.
Bone Strength: Positive effects on femoral neck strength indices (p < 0.05).
Vertebral Fractures: MK-7 reduced vertebral height loss in the lower thoracic region (p < 0.05), though absolute effect sizes were not quantified in the summary.

Limitations

Population Specificity: Results apply only to healthy postmenopausal women; efficacy in men, premenopausal women, or younger populations is unknown.
Site-Specific Effects: No significant benefits at the total hip, suggesting MK-7 may not uniformly protect all skeletal sites.
Fracture Assessment: VFA via DXA may underestimate vertebral fracture prevalence compared to radiographic methods.
Generalizability: The study did not assess dietary vitamin K intake or baseline deficiency status, which could influence outcomes.
Duration: While 3 years is long for a trial, longer-term effects on fracture risk remain unproven.

Clinical Relevance

Postmenopausal women may benefit from low-dose MK-7 supplementation (180 μg/day) to mitigate age-related bone loss, particularly at the lumbar spine and femoral neck. The reduction in ucOC/cOC ratio highlights MK-7’s role in osteocalcin activation, a process critical for bone mineralization. However, the lack of total hip effects and absence of direct fracture incidence data suggest MK-7 should complement—not replace—standard bone health strategies (e.g., calcium, vitamin D, weight-bearing exercise). Clinicians should consider individual patient profiles and consult further research before recommending MK-7 for bone protection.

Note: The study focused on MK-7 (vitamin K2), not vitamin K1 (phylloquinone), as implied in the user’s query. Results may not apply to other vitamin K forms.

Source: PubMed (PMID 23525894)

Vitamin K2 for Bone Health: Can It Help Postmenopausal Women?