In a recent study published in the journal nutrientsResearchers assessed whether the classification of “functional vitamin D deficiency” predicted the benefits of vitamin D supplementation on bone and cardiovascular health.

Study: Classification of vitamin D status based on vitamin D metabolism: a randomized controlled trial in hypertensive patients. Image credit: NatchaS / Shutterstock

background

Measurement of serum 25-hydroxyvitamin D (25(OH)D) is widely recognized as the standard method for assessing vitamin D status, although the precise thresholds that define deficiency and sufficiency are debated. continues. The relationship between serum 25(OH)D levels and vitamin D requirements is complex, with some people requiring significantly different serum levels to meet their vitamin D needs. The addition of 24,25-dihydroxyvitamin D (24,25(OH)2D) measurements and the calculation of the vitamin D metabolite ratio (VMR) from these two compounds can help identify the potential for “functional vitamin D deficiency.” It has been proposed as a marker. Improves assessment of vitamin D status beyond serum 25(OH)D alone. Further research is needed to clarify the effectiveness of VMR in predicting the benefits of vitamin D supplementation and to establish consensus on the definition of functional vitamin D deficiency.

About research

This study was a precisely designed, double-blind, placebo-controlled trial in 200 hypertensive patients with low serum 25(OH)D levels, specifically those with <75 nmol/L. This effort was part of the Styrian Hypertension Study, a larger screening effort that evaluated 518 participants to identify suitable candidates for a randomized controlled trial (RCT). The primary objective was that daily vitamin D supplementation administered at 2,800 international units (IU) over an 8-week period would improve 24-hour systolic ambulatory blood pressure (ABP) and secondary effects, including diastolic ABP and additional cardiovascular risk factors. The purpose was to investigate the effect on outcomes. Ethical approval was obtained from the Ethics Committee of the Medical University of Graz and informed consent from all participants was secured. This study was rigorously documented in the Clinical Trials Registry in accordance with the Consolidated Standards of Reporting Trials (CONSORT) 2010 guidelines.

Laboratory analysis was key in this study, using a validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) method to detect 25(OH) in serum samples stored at -80°C. D and 24,25(OH)2D were measured. October 2023. This method consistently passed internal and external quality controls, including participation in the Vitamin D External Quality Assessment Scheme (DEQAS). This study used a variety of established techniques to analyze β-CrossLaps (CTX), osteocalcin, procollagen type 1 amino-terminal propeptide (P1NP), bone-specific alkaline phosphatase (bALP), among other laboratory parameters. ) and other bone markers. .

Additional parameters related to bone and mineral metabolism were considered when reanalyzing the primary and secondary results from the original RCT of this study. Statistical analyzes were thorough, using analysis of covariance (ANCOVA) for group comparisons, with a particular focus on individuals with functional vitamin D deficiency.

research result

The study accurately collected data on VMR for 505 of the first 518 patients. Of these, 192 were identified as vitamin D deficient, with 25(OH)D levels below 50 nmol/L. This distinction allows us to thoroughly catalog participants’ baseline characteristics, stratify them based on 25(OH)D concentrations, and prepare them for a thorough investigation of vitamin D metabolites and their health effects. I arranged it. Dividing her into groups with serum levels <50 nmol/L and >50 nmol/L provided a clear comparative framework to assess vitamin D status across the cohort.

Further delineation within the data was achieved by comparing participants with 25(OH)D levels <50 nmol/L, which were further categorized based on the presence or absence of functional vitamin D deficiency. Data ranged from baseline measurements to follow-up and captured changes in mineral metabolism and cardiovascular health parameters. This long-term perspective was important for understanding the dynamic nature of the health effects of vitamin D supplementation.

Investigation of cardiovascular risk factors has become particularly revealing, and the impact of vitamin D supplementation on heart health and associated risk profiles in individuals suffering from low serum 25(OH)D levels and functional vitamin D deficiency has been particularly revealing. provided insight into how it impacts

Furthermore, when we analyzed the data from a gender-specific perspective, the results were stable and showed that the observed effects of vitamin D supplementation and functional vitamin D deficiency were consistent between male and female participants. It was shown that there is.

conclusion

In summary, this study shows that hypertensive patients with vitamin D deficiency, especially those with functional vitamin D deficiency, have improved bone health and cardiovascular risk factors with vitamin D supplementation, except for decreased parathyroid hormone (PTH) levels. It was found that no significant improvement was observed. . A notable finding was the high prevalence of diabetes and impaired glucose metabolism among people with dysfunction. Accurate measurement of vitamin D metabolites using advanced LC-MS/MS methods has not yielded significant health benefits, highlighting the complex regulation of vitamin D metabolism . This study highlights the need for further research investigating the effects of vitamin D supplementation in people with functional vitamin D deficiency.