Home Medizin Eine Vitamin-D-Supplementierung zeigt bei Bluthochdruckpatienten nur begrenzte Vorteile für die Knochen- und Herzgesundheit

Eine Vitamin-D-Supplementierung zeigt bei Bluthochdruckpatienten nur begrenzte Vorteile für die Knochen- und Herzgesundheit

von NFI Redaktion

A recent study published in the journal Nutrients investigated whether the classification of „functional vitamin D deficiency“ predicts the benefits of vitamin D supplementation for bone and cardiovascular health.


Study: Classification of Vitamin D status based on Vitamin D metabolism: A randomized controlled trial in hypertensive patients. Image source: NatchaS / Shutterstock










Study: Classification of Vitamin D status based on Vitamin D metabolism: A randomized controlled trial in hypertensive patients. Image source: NatchaS / Shutterstock

Background

The measurement of 25-hydroxyvitamin D (25(OH)D) in serum is widely considered the standard method for assessing vitamin D status, although the debate about the exact thresholds defining deficiency and sufficiency continues. The relationship between serum 25(OH)D levels and vitamin D requirements is complex, as some individuals appear to require significantly different serum levels to meet their vitamin D needs. Additional investigations are needed to clarify the efficacy of the Vitamin D Metabolite Ratio (VMR) in predicting the benefits of vitamin D supplementation and to achieve a consensus on the definition of functional vitamin D deficiency beyond serum 25(OH)D alone.

About the Study

This study was a precisely designed, double-blind, placebo-controlled trial targeting 200 hypertensive patients with low serum 25(OH)D levels, especially those below 75 nmol/L. This initiative was part of a larger screening project, the Styrian Hypertension Study, where 518 participants were evaluated to identify suitable candidates for the randomized controlled trial (RCT). The main objective was to investigate the effect of daily vitamin D supplementation at a dose of 2,800 international units (IU) over eight weeks on 24-hour ambulatory blood pressure (ABP) and secondary outcomes, including diastolic ABP and additional cardiovascular risk factors. Ethical approval was obtained from the Ethics Committee of the Medical University of Graz to ensure informed consent of all participants. This study was meticulously documented in clinical trial registries and followed the guidelines of the Consolidated Standards of Reporting Trials (CONSORT) 2010.

Laboratory analyses were crucial for this study and used a validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) method to determine 25(OH)D and 24,25(OH)2D in serum samples stored at -80°C until October 2023. This method consistently passed internal and external quality controls, including participation in the Vitamin D External Quality Assessment Scheme (DEQAS). The study also extended its scope to bone markers, including β-CrossLaps (CTX), Osteocalcin, Procollagen type 1 amino-terminal propeptide (P1NP), and bone-specific alkaline phosphatase (bALP), among other laboratory parameters, using various established techniques.

The reanalysis of the primary and secondary outcomes of the initial RCT for this investigation considered additional parameters related to bone and mineral metabolism. The statistical analysis was thorough and utilized analysis of covariance (ANCOVA) for group comparisons, with a specific focus on individuals with functional vitamin D deficiency.

Study Results

The study collected data on VMR for 505 of the original 518 individuals. Among these, 192 were found to have a vitamin D deficiency indicated by a 25(OH)D level below 50 nmol/L. This distinction laid the foundation for an in-depth investigation of vitamin D metabolites and their health impacts, cataloging and stratifying the baseline characteristics of participants based on their 25(OH)D concentrations. The division into groups with serum levels below and above 50 nmol/L provided a clear framework for assessing vitamin D status in the entire cohort.

Further differentiation of the data was done by comparing participants with 25(OH)D levels below 50 nmol/L and further categorizing them based on the presence or absence of functional vitamin D deficiency. The data ranged from baseline measurements to follow-up assessments and captured changes in mineral metabolism and cardiovascular health parameters. This longitudinal perspective was crucial for understanding the dynamic nature of vitamin D’s influence on health outcomes during supplementation.

Of particular interest was the examination of cardiovascular risk factors, providing insights into how vitamin D supplementation may affect heart health and associated risk profiles in individuals struggling with low serum 25(OH)D levels and functional vitamin D deficiency.

Additionally, the results remained consistent when analyzing the data from a gender-specific perspective, indicating that the observed effects of vitamin D supplementation and the impacts of functional vitamin D deficiency were consistent among male and female participants.

Conclusions

In conclusion, the study found that hypertensive patients with vitamin D deficiency, particularly those with functional vitamin D deficiency, did not experience significant improvements in bone health or cardiovascular risk factors through vitamin D supplementation, except for a reduction in parathyroid hormone (PTH) levels. A notable finding was the higher prevalence of diabetes and glucose metabolism disorders in individuals with functional deficiencies. Despite using advanced LC-MS/MS methods for precise measurement of vitamin D metabolites, no significant health benefits were observed, highlighting the complex regulation of vitamin D metabolism. This research underscores the need for further studies to investigate the effects of vitamin D supplementation on individuals with functional vitamin D deficiency.

Journal Reference:

  • Zelzer S., Meinitzer A., Enko D. et al. Classification of Vitamin D status based on Vitamin D metabolism: A randomized controlled trial in hypertensive patients. Nutrients (2024), DOI – 10.3390/nu16060839, https://www.mdpi.com/2072-6643/16/6/839

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