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Updated: Dec 11, 2025
Assessment of Vascular Function in Patients With Chronic Kidney Disease
Published on: June 16, 2014
Vitamin K Supplementation to Improve Vascular Stiffness in CKD: The K4Kidneys Randomized Controlled Trial
Miles D Witham1,2, Jennifer S Lees3, Myra White2
1AGE Research Group, National Institute for Health Research Newcastle Biomedical Research Centre, Translational and Clinical Research Institute, Newcastle University and Newcastle-upon-Tyne National Health Service Trust, Tyne, United Kingdom Miles.Witham@newcastle.ac.uk.
Insights
Vitamin K2 supplementation did not improve arterial stiffness or vascular health in patients with chronic kidney disease (CKD). This study found no significant benefits for vascular calcification or cardiovascular risk factors in the CKD population.
Area of Science:
- Nephrology
- Cardiology
- Nutritional Science
Background:
- Vascular calcification is a significant risk factor for cardiovascular disease (CVD) in patients with chronic kidney disease (CKD).
- Vitamin K plays a crucial role in preventing vascular calcification by activating key proteins.
- The efficacy of vitamin K supplementation in improving arterial stiffness in CKD patients remains unestablished.
Purpose of the Study:
- To investigate the effect of vitamin K2 supplementation on arterial stiffness in individuals with CKD.
- To evaluate secondary outcomes including augmentation index, calcification, blood pressure, and physical function.
Main Methods:
- A double-blind, randomized controlled trial was conducted with participants aged 18+ with CKD stages 3b-4.
- Participants received 400 µg of oral vitamin K2 or a placebo daily for one year.
- Carotid-femoral pulse wave velocity was the primary outcome measure, with a meta-analysis also performed.
Main Results:
- No significant differences were observed in pulse wave velocity, augmentation index, blood pressure, or physical function between the vitamin K2 and placebo groups at 12 months.
- Updated meta-analysis results indicated no beneficial effect of vitamin K supplementation on vascular stiffness or calcification.
- No improvements were noted in B-type natriuretic peptide or physical function.
Conclusions:
- Vitamin K2 supplementation did not demonstrate efficacy in improving vascular stiffness or other vascular health markers in patients with CKD.
- The findings suggest that vitamin K2 is not a beneficial intervention for vascular health in this patient population.
Background:
Vascular calcification, a risk factor for cardiovascular disease, is common among patients with CKD and is an independent contributor to increased vascular stiffness and vascular risk in this patient group. Vitamin K is a cofactor for proteins involved in prevention of vascular calcification. Whether or not vitamin K supplementation could improve arterial stiffness in patients with CKD is unknown.
Methods:
To determine if vitamin K supplementation might improve arterial stiffness in patients in CKD, we conducted a parallel-group, double-blind, randomized trial in participants aged 18 or older with CKD stage 3b or 4 (eGFR 15-45 ml/min per 1.73 m2). We randomly assigned participants to receive 400 microg oral vitamin K2 or matching placebo once daily for a year. The primary outcome was the adjusted between-group difference in carotid-femoral pulse wave velocity at 12 months. Secondary outcomes included augmentation index, abdominal aortic calcification, BP, physical function, and blood markers of mineral metabolism and vascular health. We also updated a recently published meta-analysis of trials to include the findings of this study.
Results:
We included 159 randomized participants in the modified intention-to-treat analysis, with 80 allocated to receive vitamin K and 79 to receive placebo. Mean age was 66 years, 62 (39%) were female, and 87 (55%) had CKD stage 4. We found no differences in pulse wave velocity at 12 months, augmentation index at 12 months, BP, B-type natriuretic peptide, or physical function. The updated meta-analysis showed no effect of vitamin K supplementation on vascular stiffness or vascular calcification measures.
Conclusions:
Vitamin K2 supplementation did not improve vascular stiffness or other measures of vascular health in this trial involving individuals with CKD.
Clinical Trial Registry Name And Registration Number:
Vitamin K therapy to improve vascular health in patients with chronic kidney disease, ISRCTN21444964 (www.isrctn.com).
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