The Effects of Vitamin D Supplementation on Musculoskeletal Health: The VITAL and DO-Health Trials

Comparative Study of Healthy Older and Younger Adults Shows They Have the Same Skin Concentration of Vitamin D3 Precursor, 7-Dehydrocholesterol, and Similar Response to UVR

Vitamin D3 synthesis in human skin is initiated by solar ultraviolet radiation (UVR) exposure of precursor 7-dehydrocholesterol (7DHC), but influence of age on the early stage of vitamin D3 metabolism is uncertain. We performed a prospective standardised study in healthy ambulant adults aged ≥65 and ≤40 years examining (1) if baseline skin 7DHC concentration differs between younger and older adults and (2) the impact of older age on serum vitamin D3 response to solar simulated UVR. Eleven younger (18-40 years) and 10 older (65-89 years) adults, phototype I-III, received low-dose UVR (95% UVA, 5% UVB, 1.3 SED) to ~35% of the body surface area. Biopsies were taken for 7DHC assay from unexposed skin, skin immediately and 24 h post-UVR, and blood sampled at baseline, 24 h and 7 d post-UVR for vitamin D3 assay. Samples were analysed by HPLC-MS/MS. Baseline skin 7DHC (mean ± SD) was 0.22 ± 0.07 and 0.25 ± 0.08 µg/mg in younger versus older adults (no significant difference). Baseline serum vitamin D3 concentration was 1.5 ± 1.5 and 1.5 ± 1.7 nmol/L in younger versus older adults, respectively, and showed a significant increase in both groups post-UVR (no significant differences between age groups). Thus, skin 7DHC concentration was not a limiting factor for vitamin D3 production in older relative to younger adults. This information assists public health guidance on sun exposure/vitamin D nutrition, with particular relevance to the growing populations of healthy ambulant adults ≥65 years.

Vitamin D supplementation may be beneficial in improving the prognosis of patients with chronic obstructive pulmonary disease in the intensive care unit: a retrospective study

Background

Vitamin D is a crucial fat-soluble vitamin that has garnered significant attention due to its potential impact on respiratory health. It is noteworthy that many patients with chronic obstructive pulmonary disease (COPD) often experience deficiencies or insufficiencies of vitamin D. To address this issue, our retrospective study aimed to explore the potential association between serum 25-hydroxyvitamin D concentration and the prognoses of COPD patients in the Intensive Care Unit (ICU).

Methods

This study utilised data from the Medical Information Marketplace in Intensive Care IV (MIMIC-IV), a database of patients admitted to the Intensive Care Unit at Beth Israel Deaconess Medical Center (BIDMC) in the United States of America, with a focus on patients with a diagnosis of COPD. These patients were categorized into two groups: those who received vitamin D supplementation during their ICU stay and those who did not. We assessed in-hospital mortality and ICU mortality outcomes. Our analysis involved various analytical tools, including Kaplan-Meier survival curves, Cox proportional risk regression models, and subgroup analyses, to investigate the relationship between vitamin D supplementation and these outcomes. Additionally, we employed propensity-score matching (PSM) to enhance the reliability of our findings.

Results

The study included a total of 3,203 COPD patients, with 587 in the vitamin D group and 2,616 in the no-vitamin D group. The Kaplan-Meier survival curve demonstrated a significant difference in survival probability between the two groups. After adjusting for potential confounders using Cox regression models, the vitamin D group exhibited a substantially lower risk of in-hospital and ICU mortalities compared to the no-vitamin D group. The hazard ratios for in-hospital and ICU mortalities in the vitamin D group were 1.7 (95% CI: 1.3, 2.3) and 1.8 (95% CI: 1.2, 2.6), respectively. Propensity-score matching (PSM) estimation yielded consistent results. Furthermore, in the subgroup analysis, female patients who received vitamin D supplementation showed a reduced risk of in-hospital mortality.

Conclusion

The study suggests that vitamin D supplementation may be linked to a reduction in in-hospital and ICU mortalities among COPD patients in the ICU. Of particular note is the potential benefit observed in terms of in-hospital mortality, especially for female patients.

Serum 25-Hydroxyvitamin D and Risk of Disability in Activities of Daily Living among the Oldest-Old: An Observational and Mendelian Randomization Study

BACKGROUND

Vitamin D deficiency and disability are both prevalent among older adults. However, the association between them has rarely been investigated in the oldest-old subjects (aged ≥80 y), and the causality remains unclear.

OBJECTIVE

This study aimed to elucidate the causal effect of vitamin D on the incident risk of disability in activities of daily living (ADL) among Chinese oldest-old based on the 2012-2018 Chinese Healthy Ageing and Biomarkers Cohort Study.

METHODS

Serum 25-hydroxyvitamin D [25(OH)D] concentrations and ADL status at baseline and follow-up interviews were documented. Cox regression models were applied among 1427 oldest-old (mean age, 91.2 y) with normal baseline ADL status. One sample Mendelian randomization (MR) analyses were performed on a subset of 941 participants with qualified genetic data, using a 25(OH)D-associated genetic risk score as the genetic instrument.

RESULTS

During a median follow-up of 3.4 y, 231 participants developed disability in ADL. Serum 25(OH)D concentration was inversely associated with the risk of disability in ADL [per 10 nmol/L increase hazard ratio (HR) 0.85; 95% CI: 0.75, 0.96]. Consistent results from MR analyses showed that a 10 nmol/L increment in genetically predicted 25(OH)D concentration corresponded to a 20% reduced risk of ADL disability (HR 0.80; 95% CI: 0.68, 0.94). Nonlinear MR demonstrated a monotonic declining curve, with the HRs exhibiting a more pronounced reduction among individuals with 25(OH)D concentrations below 50 nmol/L. Subgroup analyses showed that the associations were more distinct among females and those with poorer health conditions.

CONCLUSIONS

Our study supports an inverse causal relationship between serum 25(OH)D concentration and the risk of disability in ADL among Chinese oldest-old. This protective effect was more distinct, especially for participants with vitamin D deficiency. Appropriate measures for improving vitamin D might help reduce the incidence of physical disability in this specific age group.

Health Effects of Vitamin D Supplementation: Lessons Learned From Randomized Controlled Trials and Mendelian Randomization Studies

Vitamin D plays an important role in calcium homeostasis and many cellular processes. Although vitamin D supplements are widely recommended for community-dwelling adults, definitive data on whether these supplements benefit clinically important skeletal and extraskeletal outcomes have been conflicting. Although observational studies on effects of vitamin D on musculoskeletal and extraskeletal outcomes may be confounded by reverse causation, randomized controlled studies (RCTs) and Mendelian randomization (MR) studies can help to elucidate causation. In this review, we summarize the recent findings from large RCTs and/or MR studies of vitamin D on bone health and risk of fractures, falls, cancer, and cardiovascular disease, disorders of the immune system, multiple sclerosis, and mortality in community-dwelling adults. The primary analyses indicate that vitamin D supplementation does not decrease bone loss, fractures, falls, cancer incidence, hypertension, or cardiovascular risk in generally healthy populations. Large RCTs and meta-analyses suggest an effect of supplemental vitamin D on cancer mortality. The existence of extraskeletal benefits of vitamin D supplementations are best documented for the immune system especially in people with poor vitamin D status, autoimmune diseases, and multiple sclerosis. Accumulating evidence indicates that vitamin D may reduce all-cause mortality. These findings, in mostly vitamin D-replete populations, do not apply to older adults in residential communities or adults with vitamin D deficiency or osteoporosis. The focus of vitamin D supplementation should shift from widespread use in generally healthy populations to targeted vitamin D supplementation in select individuals, good nutritional approaches, and elimination of vitamin D deficiency globally. © 2023 American Society for Bone and Mineral Research (ASBMR).