Effect of 6-Month Vitamin D Supplementation on Plasma Matrix Gla Protein in Older Adults

Studies on the synergistic Interplay of Vitamin D and K for Improving Bone and Cardiovascular Health

Nutrients perform their roles either directly or through interaction with other nutrients inside our body. The nature of interactions between nutrients can be synergistic, which brings about maximum benefit to the host, or antagonistic, i.e., one nutrient affects the uptake and availability of other nutrients in the body. These interactions need to be critically analysed and acknowledged to harness their positive health benefits. Combining nutrients having a synergistic effect may help in lowering the threat of cardiovascular ailment, osteoporosis, and other health issues. This study aims to qualitatively review the information that is currently available upon the synergistic effects of co-supplementing Vitamin D and K on bone and cardiovascular health among various age groups. The methodology followed the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. A structured search of two databases-PubMed and Google Scholar—was carried out, and articles were identified that focused upon the dual supplementation of Vitamin D and K, which has been shown to improve bone and cardiovascular health among users. The search was restricted to the English language, conducted, and published between 2006 and 2021. Overall, 12 studies involving 8216 participants were included in the qualitative analysis. Among these, 5 were randomized controlled trials, 6 were observational studies, and 1 was interventional studies. The results were interpreted based on improved bone health by assessing the progress in Bone Mineral Content (BMC), lower extremity function, Bone Mineral Density (BMD), and bone turnover. In contrast, improvement in cardiovascular health was recorded based on the Carotid Intima-media Thickness (CIMT), arterial stiffness, high systolic and diastolic blood pressure, and the structure of the heart. Out of a total 12 studies, 11 studies showed that Vitamin D work in synergy with Vitamin K and also has a significant role in improving bone fractures, low BMD, and cardiovascular disorders. Further research and clinical trials on these Vitamins in different age groups and disease conditions are warranted.

The Role of Vitamin K in CKD-MBD

PURPOSE OF REVIEW

We describe the mechanism of action of vitamin K, and its implication in cardiovascular disease, bone fractures, and inflammation to underline its protective role, especially in chronic kidney disease (CKD).

RECENT FINDINGS

Vitamin K acts as a coenzyme of y-glutamyl carboxylase, transforming undercarboxylated in carboxylated vitamin K-dependent proteins. Furthermore, through the binding of the nuclear steroid and xenobiotic receptor, it activates the expression of genes that encode proteins involved in the maintenance of bone quality and bone remodeling. There are three main types of K vitamers: phylloquinone, menaquinones, and menadione. CKD patients, for several conditions typical of the disease, are characterized by lower levels of vitamin K than the general populations, with a resulting higher prevalence of bone fractures, vascular calcifications, and mortality. Therefore, the definition of vitamin K dosage is an important issue, potentially leading to reduced bone fractures and improved vascular calcifications in the general population and CKD patients.

Vitamin D Effects on Bone Homeostasis and Cardiovascular System in Patients with Chronic Kidney Disease and Renal Transplant Recipients

Poor vitamin D status is common in patients with impaired renal function and represents one main component of the complex scenario of chronic kidney disease-mineral and bone disorder (CKD-MBD). Therapeutic and dietary efforts to limit the consequences of uremia-associated vitamin D deficiency are a current hot topic for researchers and clinicians in the nephrology area. Evidence indicates that the low levels of vitamin D in patients with CKD stage above 4 (GFR < 15 mL/min) have a multifactorial origin, mainly related to uremic malnutrition, namely impaired gastrointestinal absorption, dietary restrictions (low-protein and low-phosphate diets), and proteinuria. This condition is further worsened by the compromised response of CKD patients to high-dose cholecalciferol supplementation due to the defective activation of renal hydroxylation of vitamin D. Currently, the literature lacks large and interventional studies on the so-called non-calcemic activities of vitamin D and, above all, the modulation of renal and cardiovascular functions and immune response. Here, we review the current state of the art of the benefits of supplementation with native vitamin D in various clinical settings of nephrological interest: CKD, dialysis, and renal transplant, with a special focus on the effects on bone homeostasis and cardiovascular outcomes.

Vitamin K and D Supplementation and Bone Health in Chronic Kidney Disease-Apart or Together?

Vitamin K (VK) and vitamin D (VD) deficiency/insufficiency is a common feature of chronic kidney disease (CKD), leading to impaired bone quality and a higher risk of fractures. CKD patients, with disturbances in VK and VD metabolism, do not have sufficient levels of these vitamins for maintaining normal bone formation and mineralization. So far, there has been no consensus on what serum VK and VD levels can be considered sufficient in this particular population. Moreover, there are no clear guidelines how supplementation of these vitamins should be carried out in the course of CKD. Based on the existing results of preclinical studies and clinical evidence, this review intends to discuss the effect of VK and VD on bone remodeling in CKD. Although the mechanisms of action and the effects of these vitamins on bone are distinct, we try to find evidence for synergy between them in relation to bone metabolism, to answer the question of whether combined supplementation of VK and VD will be more beneficial for bone health in the CKD population than administering each of these vitamins separately.

Post hoc analysis of a randomised controlled trial: effect of vitamin D supplementation on circulating levels of desmosine in COPD

Background

Vitamin D supplementation lowers exacerbation frequency in severe vitamin D-deficient patients with COPD. Data regarding the effect of vitamin D on elastin degradation are lacking. Based on the vitamin's anti-inflammatory properties, we hypothesised that vitamin D supplementation reduces elastin degradation, particularly in vitamin D-deficient COPD patients. We assessed the effect of vitamin D status and supplementation on elastin degradation by measuring plasma desmosine, a biomarker of elastin degradation.

Methods

Desmosine was measured every 4 months in plasma of 142 vitamin D-naïve COPD patients from the Leuven vitamin D intervention trial (100 000 IU vitamin D3 supplementation every 4 weeks for 1 year).

Results

No significant association was found between baseline 25-hydroxyvitamin D (25(OH)D) and desmosine levels. No significant difference in desmosine change over time was found between the placebo and intervention group during the course of the trial. In the intervention arm, an unexpected inverse association was found between desmosine change and baseline 25(OH)D levels (p=0.005).

Conclusions

Vitamin D supplementation did not have a significant overall effect on elastin degradation compared to placebo. Contrary to our hypothesis, the intervention decelerated elastin degradation in vitamin D-sufficient COPD patients and not in vitamin D-deficient subjects.

Vitamin D supplementation does not have a significant overall effect on elastin degradation. Vitamin D decelerates elastin degradation in vitamin D-sufficient, but not in vitamin D-deficient, COPD patients.https://bit.ly/2A9H9P7

Combined low vitamin D and K status amplifies mortality risk: a prospective study

Objective

To explore the association of both plasma vitamin D and K concentrations with all-cause mortality, cardiovascular mortality, and cardiovascular events in the general population.

Methods

We studied 4742 participants of the Prevention of REnal and Vascular ENd-Stage Disease (PREVEND) Study. At baseline, vitamin D and K status was determined by measurement of 25-hydroxyvitamin D [25(OH)D] and dephosphorylated uncarboxylated matrix Gla protein (dp-ucMGP), respectively. Patients were categorized into: 25(OH)D < 50 or ≥ 50 nmol/L and dp-ucMGP < 361 or ≥ 361 pmol/L with 25(OH)D > 75 nmol/L and dp-ucMGP < 361 pmol/L as reference. Cause of death was coded according to International Classification of Diseases 9&10 codes from the 2001-2003 examination until date of death/event or censoring date (January 1st, 2017).

Results

Mean age was 52.6 ± 11.9 years and 2513 (53%) were female. During a median of 14.2 year follow-up, 620 participants died of which 142 were due to cardiovascular causes. Combined low vitamin D and K status was present in 970 participants (20%) and was associated with a greater risk of all-cause mortality compared to high vitamin D and high vitamin K status group (n = 1424) after adjusting for potential confounders: hazard ratio 1.46 (95% confidence intervals 1.12–1.90). We observed similar trends, albeit non-significant for cardiovascular mortality, and cardiovascular events: 1.42 (0.79–2.55), 1.28 (0.93–1.77), respectively.

Conclusions

Combined low vitamin D and K status are associated with increased all-cause mortality risk and possibly with cardiovascular mortality and cardiovascular events compared with adequate vitamin D and K status. Future studies should investigate the effect of combined vitamin D and K supplementation on clinical outcomes.

Electronic supplementary material

The online version of this article (10.1007/s00394-020-02352-8) contains supplementary material, which is available to authorized users.

European Biological Variation Study (EuBIVAS): within- and between-subject biological variation estimates of β-isomerized C-terminal telopeptide of type I collagen (β-CTX), N-terminal propeptide of type I collagen (PINP), osteocalcin, intact fibroblast growth factor 23 and uncarboxylated-unphosphorylated matrix-Gla protein-a cooperation between the EFLM Working Group on Biological Variation and the International Osteoporosis Foundation-International Federation of Clinical Chemistry Committee on Bone Metabolism

We have calculated the biological variation (BV) of different bone metabolism biomarkers on a large, well-described cohort of subjects. BV is important to calculate reference change value (or least significant change) which allows evaluating if the difference observed between two consecutive measurements in a patient is biologically significant or not.

INTRODUCTION

Within-subject (CV_I) and between-subject (CV_G) biological variation (BV) estimates are essential in determining both analytical performance specifications (APS) and reference change values (RCV). Previously published estimates of BV for bone metabolism biomarkers are generally not compliant with the most up-to-date quality criteria for BV studies. We calculated the BV and RCV for different bone metabolism markers, namely β-isomerized C-terminal telopeptide of type I collagen (β-CTX), N-terminal propeptide of type I collagen (PINP), osteocalcin (OC), intact fibroblast growth factor 23 (iFGF-23), and uncarboxylated-unphosphorylated Matrix-Gla Protein (uCuP-MGP) using samples from the European Biological Variation Study (EuBIVAS).

METHODS

In the EuBIVAS, 91 subjects were recruited from six European laboratories. Fasting blood samples were obtained weekly for ten consecutive weeks. The samples were run in duplicate on IDS iSYS or DiaSorin Liaison instruments. The results were subjected to outlier and variance homogeneity analysis before CV-ANOVA was used to obtain the BV estimates.

RESULTS

We found no effect of gender upon the CV_I estimates. The following CV_I estimates with 95% confidence intervals (95% CI) were obtained: β-CTX 15.1% (14.4-16.0%), PINP 8.8% (8.4-9.3%), OC 8.9% (8.5-9.4%), iFGF23 13.9% (13.2-14.7%), and uCuP-MGP 6.9% (6.1-7.3%).

CONCLUSIONS

The EuBIVAS has provided updated BV estimates for bone markers, including iFGF23, which have not been previously published, facilitating the improved follow-up of patients being treated for metabolic bone disease.

The Relationship between Dietary Vitamin K and Depressive Symptoms in Late Adulthood: A Cross-Sectional Analysis from a Large Cohort Study

Few studies assessed the associations between dietary vitamin K and depressive symptoms. We aimed to investigate the association between dietary vitamin K and depressive symptoms in a large cohort of North American People. In this cross-sectional analysis, 4,375 participants that were aged 45⁻79 years from the Osteoarthritis Initiative were included. Dietary vitamin K intake was collected through a semi-quantitative food frequency questionnaire and categorized in quartiles. Depressive symptoms were diagnosed using the 20-item Center for Epidemiologic Studies-Depression (CES-D) ≥ 16. To investigate the associations between vitamin K intake and depressive symptoms, logistic regression analysis were run, which adjusted for potential confounders. Overall, 437 (=10%) subjects had depressive symptoms. After adjusting for 11 confounders, people with the highest dietary vitamin K intake had lower odds of having depressive symptoms (OR = 0.58; 95%CI: 0.43⁻0.80). This effect was only present in people not taking vitamin D supplementation. In conclusion, higher dietary vitamin K intake was significantly associated with a lower presence of depressive symptoms, also after accounting for potential confounders. Future longitudinal research is required to explore the directionality of the association.