Researchers have recently reported that vitamin K supplementation plays an important role in preventing fractures.
Vitamin K exists in several forms including vitamin K1 (phytonadione) and vitamin K2 (menaquinone). In a new study, investigators reviewed data from 7 studies conducted with postmenopausal women to evaluate their fracture risk and its association with their intake of vitamin K. Each of the studies reviewed had at least 50 subjects and lasted a minimum of 2 years.
The meta-analysis of the data showed that vitamin K1 and vitamin K2 supplementation reduced serum under-carboxylated osteocalcin levels regardless of dose. Osteocalcin is a calcium-binding protein in bone and is essential for the normal mineralization of bone. Osteocalcin requires vitamin K as a cofactor in order to become optimally active, which occurs after carboxylation. Thus, under-carboxylated osteocalcin, caused by insufficient vitamin K levels, is less active, resulting in decreased calcium binding and bone mineralization. The researchers also found that vitamin K consumption had inconsistent effects on total serum osteocalcin levels and had no effect on bone resorption. However, the study revealed that high-dose vitamin K1 and vitamin K2 supplementation improved bone strength indices in the hip and reduced the incidence of clinical fractures overall.
Thus, the researchers stated, “The review of the reliable literature confirmed the effect of vitamin K1 and vitamin K2 supplementation on the skeleton of postmenopausal women mediated by mechanisms other than bone mineral density and bone turnover.”
Reference:
Iwamoto J, Sato Y, Takeda T, Matsumoto H. High-dose vitamin K supplementation reduces fracture incidence in postmenopausal women: a review of the literature. Nutr Res. 2009 Apr;29(4):221-8.