Effects of vitamin K on Calcium and bone metabolism
The term vitamin K is used for a family of naphthoquinones: the natural vitamins K1 and K2. [...] Vitamin K1 is synthesized by plants. Menaquinone is a large family of vitamins K2 [...] synthesized by bacteria.
The essentiality of vitamin K is dominantly defined by its role as a cofactor for the vitamin K-dependent carboxylase, an enzyme that is responsible for the post-translational conversion of the GLA residues in a limited number of proteins including osteocalcin. [...]
Osteocalcin, the most abundant noncollagenous protein in bone, is produced by osteoblasts during bone matrix formation. The GLA residue, when it is carboxylated, binds the Calcium ions. If sufficient vitamin K is not available, some or all of the GLA residues are de-carboxylated. [...] Epidemiological studies have demonstrated that elderly women with high circulating levels of undercarboxylated osteocalcin have an increased risk of hip fractures [...]
Vitamin K supplementation leads to significant reductions of Calcium in urine [...], suggesting a decrease in bone resorption. [...] Vitamin K2 can influence differentiation and functions of bone marrow cells. Consequently, vitamin K2 can facilitate bone metabolism [...] and modulate cellular differentiation and functions in bone marrow.
In recent literature there is evidence that vitamin K is an important modulating factor of bone physiology. [...] Epidemiological studies demonstrate that both low vitamin K intake as well as unphysiological low biochemical parameters (e.g. undercarboxylated osteocalcin) are associated to an increased osteoporotic fracture risk. [...] Age and hormone-related changes associated with menopause also influence the serum levels of undercarboxylated osteocalcin.
[...] There is, however, impressive evidence from Japanese research groups that very high pharmacological doses of vitamin K2 are able to prevent further bone weakening and also to reduce fracture risk.
Armin Zittermann: Effects of vitamin K on calcium and bone metabolism. Current Opinion in Clinical Nutrition and Metabolic Care.
Reducing the risk of fractures with Calcium and Vitamin D
Calcium and Vitamin D therapy has been recommended for older persons, with key risk factors including decreased bone mineral density (BMD), osteoporotic fractures, increased bone remodelling as a result of secondary hyperparathyroidism and increased propensity to falls. [...] Integration of Calcium and Vitamin D is a key component in the prevention and treatment of osteoporosis. [...] Based on the relationship between serum 25(OH)D - dihydroxycholecalciferol, the active form of vitamin D3, BMD, bone turnover, we suggest that 50 nmol/l is the appropriate serum 25(OH)D threshold to define vitamin D insufficiency. Supplementation should therefore generally aim to increase 25(OH)D levels within the 50-75 nmol/l range. This level can be achieved with a dose of 800 IU/day of vitamin D [...], the dose that was used in successful fracture prevention [...]
Osteoporotic fractures are a growing health problem [...]. The risk of fracture increases exponentially with age and with a decrease in bone mineral density (BMD), often associated with increased bone remodelling rate, resulting in a net bone reabsorption and a subsequent decrease of bone strength.
[...] The supplement of Calcium and Vitamin D in elderly individuals with a poor nutritional status, can reduce bone resorption, increase bone mineral density and reduce the risk of fractures.
[...] In conclusion, a low intake of Calcium and a poor Vitamin D status are key factors for osteoporosis and fracture risk. The supplement of Calcium and Vitamin D is an essential component in the prevention and treatment of osteoporosis and osteoporotic fractures. It improves bone mineralization [...].
The supplement should guarantee the increase in levels of dihydroxycholecalciferol in the 50-75 nmol/l range. This target can be reached with a daily dose of 800 IU of Vitamin D, the dose used in many successful studies on the prevention of fractures. [...] The calcium balance can be optimized with daily intakes of Calcium [...].
Paul Lips, Roger Bouillon, Natasja M. van Schoor, Dirk Vanderschueren, Sabine Verschueren, Natalia Kuchuk, Koen Milisen, and Steven Boonen: Reducing fracture risk with Calcium and Vitamin D. Clinical Endocrinology.