Vitamin K and Bone Health

Numerous studies have shown that nutrients and vitamins, including vitamin D, vitamin C, and, more recently, vitamin K, play a significant role in maintaining optimal bone health, especially among older adults.

Vitamin K is the term used to name a family of fat-soluble compounds which, although differing in origin and/or function, share a common 2-methyl-1,4-naphthoquinone ring and yet differ in the lateral (lipophilic) chains attached at position 3. The three main forms are vitamin PK or phylloquinone (PK), vitamin K2 or menaquinones (MKn), and vitamin K3 or menadione.

Vitamin K acts as a cofactor for γ-glutamyl carboxylase (GGCX), which catalyzes the carboxylation of vitamin K-dependent proteins. This enzyme catalyzes the post-translational γ-carboxylation of glutamic acid residues (Glu), placed in vitamin K-dependent proteins, into γ-carboxylated glutamic acid residues (Gla). Among the family of Gla proteins, 17 different members have been recognized: S-prothrombin, factor VII belonging to the coagulative cascade, matrix Gla protein (MGP), osteocalcin (OC), among others, playing a role in modulating bone mineralization, in addition to vascular health. Thus, the vitamin plays a considerable role in maintaining bone strength, as it regulates bone remodeling by promoting osteoblast-osteocyte transition and limiting osteoclastogenesis.

Several points of experimental evidence delineate that vitamin K plays an important role in bone health. Low vitamin K intake, low circulating vitamin K levels, high serum levels of undercarboxylated osteocalcin, or low serum levels of total osteocalcin have been associated with an increased risk of bone fractures in observational studies and controlled trials.

In an intervention study with 241 osteoporosis patients in the vitamin K2-treated group (n = 120), who received 45mg/day orally of MK-4 for 12 months, a lower incidence of bone fractures was found than in the control group.

In another double-blind, randomized, controlled study with 244 postmenopausal women, MK-7 capsules (180μg MK-7/day) or placebo were received for 3 years to investigate their effect on vertebral fractures. MK-7 significantly decreased the height loss of the lower thoracic region at the midpoint of the vertebrae after 2 and 3 years of intervention.

In addition to vitamin K supplementation for bone health, its co-administered supplementation with calcium, vitamin D, and magnesium may improve bone quality and reduce fracture risk in patients with osteoporosis.

Reference: 1)Fusaro M, Cianciolo G, Brandi ML, et al. Vitamin K and Osteoporosis. Nutrients. 2020;12(12):3625. Published 2020 Nov 25. doi:10.3390/nu12123625

2)Rodríguez-Olleros Rodríguez C, Díaz Curiel M. Vitamin K and Bone Health: A Review on the Effects of Vitamin K Deficiency and Supplementation and the Effect of Non-Vitamin K Antagonist Oral Anticoagulants on Different Bone Parameters. J Osteoporos. 2019 ;2019:2069176. Published 2019 Dec 31. doi:10.1155/2019/2069176

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