Vitamin K Metabolism and Its Impacts on Vascular and Bone Health

Vitamin K comprises a family of fat-soluble compounds essential for the activation of Gla-proteins through γ-carboxylation. Nutritionally, phylloquinone (vitamin K1) is obtained from leafy vegetables, while menaquinones (vitamin K2) arise from gut microbiota or conversion from K1. Once absorbed, vitamin K undergoes epoxide reduction and recycling via the vitamin K cycle, ensuring the regeneration of the active cofactor. In the vascular system, carboxylated matrix Gla-protein prevents pathological calcification of arterial walls, preserving elasticity and reducing cardiovascular risk. In bone, γ-carboxylated osteocalcin and other Gla-proteins regulate mineral deposition and osteoblast function, thereby supporting bone density and microarchitecture. Emerging evidence also highlights non-classical roles such as transcriptional regulation via the steroid and xenobiotic receptor, linking vitamin K to extracellular matrix gene expression and anti-inflammatory pathways. Dysregulation of vitamin K metabolism, whether through genetic variants, insufficient dietary intake, antibiotic-induced dysbiosis or pharmacological antagonism, impairs Gla-protein activity, favouring vascular calcification, osteoporosis and related morbidities. Understanding the interplay between dietary sources, enzymatic conversion and extrahepatic distribution of K1 and K2 isoforms is thus central to both vascular and skeletal health strategies, with practical applications ranging from dietary recommendations to novel therapeutic agents that restore or mimic vitamin K function.

Research from Nature Portfolio

A recent study investigated heterozygous variants in the gene encoding matrix Gla-protein, revealing that single amino-acid substitutions can induce endoplasmic reticulum stress and apoptosis in chondrocytes, leading to a dominant spondyloepiphyseal dysplasia distinct from classical syndromes. Using both patient-derived cells and knock-in mouse models, researchers demonstrated that impaired γ-carboxylation of the mutated protein abolished its calcification-inhibitory function, precipitating aberrant skeletal development and vascular ossification. This work underscores the sensitivity of vascular and bone tissues to subtle disruptions in vitamin K-dependent protein maturation and highlights the importance of genetic screening and targeted supplementation strategies in predisposed individuals.

Vitamin K Metabolism and Its Impacts on Vascular and Bone Health publication trend

The graph below shows the total number of articles in vitamin k metabolism and its impacts on vascular and bone health across all publications each year (not limited to Nature Index journals).

Technical terms

γ-carboxylation: Post-translational modification by which vitamin K-dependent enzymes convert specific glutamate residues in proteins to γ-carboxyglutamate, enabling calcium binding.

Vitamin K cycle: Cellular enzymatic pathway involving vitamin K epoxide reductase and γ-glutamyl carboxylase that recycles vitamin K between active and epoxide forms to sustain repeated carboxylation reactions.

Matrix Gla-protein (MGP): Vitamin K-dependent extracellular matrix protein that inhibits inappropriate mineral deposition in vascular and cartilaginous tissues.

Steroid and xenobiotic receptor (SXR): Nuclear receptor activated by vitamin K2 that regulates transcription of genes involved in bone matrix formation and detoxification.

References

1. Specific heterozygous variants in MGP lead to endoplasmic reticulum stress and cause spondyloepiphyseal dysplasia. Nature Communications (2023).
2. Vitamin K: a potential missing link in critical illness–a scoping review. Critical Care (2024).
3. Vitamin K: Double Bonds beyond Coagulation Insights into Differences between Vitamin K1 and K2 in Health and Disease. International Journal of Molecular Sciences (2019).
4. Recent trends in the metabolism and cell biology of vitamin K with special reference to vitamin K cycling and MK-4 biosynthesis. Journal of Lipid Research (2014).
5. Vitamin K: food composition and dietary intakes. Food & Nutrition Research (2012).
6. Vitamin K-Antagonists Accelerate Atherosclerotic Calcification and Induce a Vulnerable Plaque Phenotype. PLOS ONE (2012).
7. Comparison of menaquinone-4 and menaquinone-7 bioavailability in healthy women. Nutrition Journal (2012).
8. Steroid and Xenobiotic Receptor SXR Mediates Vitamin K2-activated Transcription of Extracellular Matrix-related Genes and Collagen Accumulation in Osteoblastic Cells*♦. Journal of Biological Chemistry (2006).