Vitamin K2 and bone loss after menopause: a 3-year trial

What does the research say?

In this Dutch trial, healthy postmenopausal women who took a daily vitamin K2 (MK-7) supplement for three years lost less bone density at the spine and hip than women taking a placebo. The effect was modest, but it lasted for the full three years.

The science

Bone density usually falls after menopause. Vitamin K2 activates osteocalcin, a protein involved in binding calcium into bone, and MK-7 is the long-acting form found in natto.

Women were randomised to 180 µg of MK-7 or placebo daily. MK-7 improved vitamin K status (lower levels of inactive osteocalcin) and reduced the age-related decline in bone mineral content and density at the lumbar spine and femoral neck. Measures of bone strength also held up better.

Key findings

• Less bone loss at the lumbar spine and femoral neck over 3 years.
• Improved vitamin K status, shown by lower inactive osteocalcin.
• Bone strength measures declined less in the MK-7 group.
• The supplement was well tolerated.

Limitations

• Only healthy postmenopausal women were studied, so results may not apply to men or people with osteoporosis.
• The trial measured bone density, not fractures.
• It tested a supplement dose; the amount from food varies widely.
• Anyone taking warfarin or another vitamin K antagonist should not change their vitamin K intake without medical advice.

References

1. Knapen MHJ, Drummen NE, Smit E, Vermeer C, Theuwissen E. Three-year low-dose menaquinone-7 supplementation helps decrease bone loss in healthy postmenopausal women. Osteoporos Int. 2013;24(9):2499–2507. doi.org/10.1007/s00198-013-2325-6