Osteoporosis is a condition where bone tissue becomes less dense over time. Loss of bone density significantly increases the risk of bone fractures. Some studies suggest that vitamin K may help treat or prevent osteoporosis, but results are controversial.(53)
Although it can affect both older men and women, it is recognized as a major health issue for postmenopausal women since decreases in the hormone estrogen can result in increases in demineralization of bone.(53)
Vitamin K is important for healthy bones because of its interactions with bone proteins. Through a process called carboxylation, vitamin K changes these proteins so they can bind to calcium, an important mineral for bones:(1, 4, 22, 53)
Protein | Importance in Bone Health |
---|---|
Osteocalcin |
Plays a role in:
|
MGP |
|
Protein S | The role of protein S in bone density is unclear, except that children born with a deficiency in this protein have reduced bone density. |
Vitamin K deficiency can result in non-carboxylated proteins. Higher blood serum levels of non-carboxylated bone proteins are linked to reduced bone density and greater risk of bone fracture in elderly women. Additionally, research indicates that drugs that block vitamin K activity (e.g., anticoagulant drugs) may reduce bone density in the arm.(1, 4, 22, 53)
Studies have shown that postmenopausal women and elderly men who take vitamin K1 supplements have increased levels of carboxylated bone proteins. Whether or not use of vitamin K supplements improves bone density and decreases risk of fractures is still unclear, however, because of conflicting study results.(1)
Research shows a link between vitamin K levels and bone health in older populations or in patients with diseases that cause vitamin K deficiency and increased risk for osteoporosis. Animal and clinical studies suggest vitamin K2 or vitamin K1 in combination with other supplements may help:
Post-Menopausal Women. In a 14-week controlled study involving 33 healthy postmenopausal women, combining several supplements (including 500 µg of vitamin K) with low-glycemic dietary intake (similar to a Mediterranean diet) and mild exercise significantly reduced markers for bone turnover. The untreated placebo group, on the other hand, exhibited a 19% increase in these markers, which are indicative of less healthy bone metabolism.(53)
Vitamin K combined with vitamin D and calcium supplements may also be beneficial. Results of a clinical study involving post-menopausal Korean women showed that taking the supplements for 6 months increased bone density. Levels of under-carboxylated bone proteins were also reduced.(56)
Vitamin K2 has been found to promote bone formation in postmenopausal women.(54)
Clinical studies suggest vitamin K2 may also prevent new fractures in patients with osteoporosis.(54)
Conversely, some research showed that increased vitamin K intake, by itself, showed no benefit for bone density in some groups:
It is difficult to figure out if assess the benefit of vitamin K on osteoporosis based on bone density alone. This is due to the wide array of study types involving disparate populations and different forms of vitamin K.(3)
However, a 2006 meta-analysis was conducted on similar type studies measuring bone density and fracture risk. The researchers concluded that vitamin K supplementation (primarily vitamin K2) does offer bone-strengthening benefits - particularly for Asian people. Vitamin K may also be helpful in some people at risk for vitamin K deficiency, particularly when combined with other supplements or healthy diets.(3, 53-57)