Vitamin K2 supplementation may slow the progression of arterial stiffness in kidney transplant recipients, investigators reported at the 2023 American Transplant Congress in San Diego, California.
Vitamin K deficiency is common among kidney transplant recipients and likely contributes to progressive vascular calcification and stiffness linked with early death. Vitamin K deficiency prevents carboxylation of matrix Gla protein (MGP), a potent inhibitor of vascular calcification. To test the value of vitamin K supplementation in this population, investigators randomly assigned 40 vitamin K deficient kidney transplant recipients to 12 weeks of treatment with vitamin K2 supplements (menaquinone-7; 360 µg per day) or placebo. The investigators defined vitamin K deficiency as a plasma dephosphorylated uncarboxylated matrix gla-protein (dp-ucMGP) level of 500 pmol/L or higher.
Over 12 weeks, supplementation improved vitamin K status compared with baseline (dp-ucMGP decreased by 385 pmol/L), but most patients remained deficient.1
Vitamin K supplementation over 12 weeks did not slow calcification propensity, as measured by calciprotein particle maturation time, Daan Kremer, MD, of the University of Groningen and University Medical Center in the Netherlands, and colleagues reported. Pulse wave velocity, a marker of arterial stiffness, however, decreased by 0.06 m/s in the vitamin K supplementation group, whereas it increased by 0.27 m/s in the placebo group. The effect was independent of blood pressure change. At baseline, pulse wave velocity values were similar in the vitamin K group and placebo group: 8.3 vs 8.4 m/s.
The findings indicate that vitamin K has vascular effects independent of calciprotein particles, according to the investigators, who published their findings in the American Journal of Transplantation.2
In an interview, Dr Kremer said, “I think it is too soon to say that clinicians should prescribe vitamin K2 supplements to kidney transplant recipients. Although the study results are encouraging, the effects of vitamin K2 supplementation on vascular stiffness must be repeated and confirmed in a larger study prior to clinical implementation.”
Disclosure: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.
- Kremer D, Eelderink C, Riphagen IJ, et al. Effect of vitamin K2-supplementation on calcification propensity and vascular stiffness in vitamin K-deficient kidney transplant recipients: A randomized, double-blind, placebo-controlled clinical trial. Presented at: ATC 2023; June 3-7, San Diego, California. Abstract C184.
- Eelderink C, Kremer D, Riphagen IJ, et al. Effect of vitamin K supplementation on serum calcification propensity and arterial stiffness in vitamin K-deficient kidney transplant recipients: A double-blind, randomized, placebo-controlled clinical trial. Am J Transplant. doi:10.1016/j.ajt.2022.12.015