Vitamin K and muscle health: mechanisms and clinical perspectives in sarcopenia and beyond: narrative review.

Vitamin K, a fat-soluble micronutrient traditionally recognized for its role in blood coagulation, has increasingly been implicated as a micronutrient with emerging roles in skeletal muscle health. Experimental and clinical evidence now suggests that vitamin K influences skeletal muscle through both γ-carboxylation-dependent pathways-mediated by osteocalcin, matrix Gla protein (MGP), and growth arrest-specific 6 (Gas6)-and through non-carboxylation mechanisms, including anti-inflammatory, antioxidant, mitochondrial-regulatory, and ferroptosis-suppressing effects. Observational studies associate higher vitamin K intake and status with greater muscle strength, higher muscle mass, and better physical performance among older adults. However, findings from randomized controlled trials (RCTs) remain inconclusive, possibly due to differences in vitamin K isoforms, dosage, intervention duration, and study populations. Beyond age-related sarcopenia, vitamin K may also play a potentially protective role in muscle dysfunction associated with chronic diseases, including dialysis-related cramps and metabolic disorders. This review synthesizes recent mechanistic insights and clinical evidence, highlighting vitamin K as a biologically plausible contributor that is supported primarily by observational and mechanistic evidence for the prevention and management of sarcopenia and other muscle-related disorders, though its role remains incompletely validated.