However, no significant difference was found between the MK-7 and standard care groups for arterial stiffness, as measured by carotid femoral pulse wave velocity (cfPWV).
The Thai researchers emphasise: “This study represents the first RCT to investigate the impact of vitamin K2 supplementation on vascular stiffness in ESKD patients who had high risk of cardiovascular disease due to severe arterial stiffness as determined by PWV.”
“Vitamin K supplementation was found associated with a lower rate of arterial stiffness progression in chronic hemodialysis patients with diabetes,” they conclude, suggesting the potential for further research to investigate the potential benefits for dietary intervention within this group.
Kidney disease outcomes
It has been established that cardiovascular morbidity and mortality are the leading causes of death in patients with CKD and ESKD, whilst a strong prevalence of malnutrition and sarcopenia has also been noted within these individuals.
Furthermore, chronic inflammation has also been associated with such cardiovascular outcomes in dialysis patients, following the processes of hyperphosphatemia and hypercalcemia which contribute to arterial stiffness and increased blood pressure.
Yet, it has been noted that nutrition can play an important role in improving the survival chances. Specifically, there has been interest into the potential of vitamin K supplementation in reducing risk of adverse outcomes, due to its involvement in the activity of the matrix Gla protein (MGP) within the blood vessel wall.
Therefore, vitamin K deficiencies, of which there is a strong prevalence within dialysis patients, may enhance vascular calcification progression. Following this, the researchers sought to investigate the efficacy of vitamin K2 menaquinone-7 (MK-7) supplementation in reducing arterial stiffness in chronic HD patients.
The randomised control trial was conducted between 2021 and 2022, utilising 96 Thai patients diagnosed with HD; defined by the presence of high cfPWV (≥ 10 m/s).
Patients were randomly assigned to be administered either the oral MK-7 supplement (375 mcg) once daily or standard care, over a period of 24 weeks. The researchers measured cfPWV using the SphygmoCor XCEL Model EM4 to determine changes in arterial stiffness at weeks 12 and 24, following taking baseline measurements.
Following the comparable baseline parameters between the two groups, it was reported that there were no significant differences between them in terms of cPWV change at 24 weeks.
However, it was noted that MK-7 significantly decreased cPWV readings in those patients with diabetes. In addition, the MK-7 supplemented group showed a slowed the rate of arterial stiffness progression, which was even more prominent within those with diabetes.
“Inadequate vitamin K intake has been reported in both CKD and ESKD populations, partly due to potassium-rich food restrictions, with dialysis patients displaying a 4.5-fold increase in dp-ucMGP levels, indicating a significant deficiency of vitamin K,” the report highlights, with regards to the relevance of this area of study and the potential need for dietary intervention within this group.
Hypothesising the significant effects noted in the diabetic patients, the researchers note that a previous study observed that vitamin K was able to enhance insulin sensitivity in pancreatic β-cells, thereby reducing glucose levels. They add that the vitamin’s role in osteocalcin activation, which enhances pancreatic β-cell function and ultimately insulin sensitivity, may also describe the effect.
Following this, the researchers highlight: “Therefore, our study suggests that vitamin K2 may benefit arterial stiffness dependent on glucose levels”, yet they emphasise the need for future research to examine the long-term outcomes to validate this theory.
“Effect of Menaquinone-7 Supplementation on Arterial Stiffness in Chronic Hemodialysis Patients: A Multicenter Randomized Controlled Trial”
by Nuanjanthip Naiyarakseree, Jeerath Phannajit, Wichai Naiyarakseree, Nanta Mahatanan, Pagaporn Asavapujanamanee, Sookruetai Lekhyananda, Supat Vanichakarn, Yingyos Avihingsanon, Kearkiat Praditpornsilpa, Somchai Eiam-Ong and Paweena Susantitaphong