Low Vitamin D Status Is Associated with Increased Risk of Mortality in Korean Men and Adults with Hypertension: A Population-Based Cohort Study

Serum 25-hydroxyvitamin D levels and risk of all-cause and cause-specific mortality: A 14-year prospective cohort study

BACKGROUND & AIMS

The circulating vitamin D level that is optimal for health is unknown. This study aimed to examine the association between circulating vitamin D level and risk of all-cause and cause-specific mortality.

METHODS

This prospective cohort study included 18,797 Korean adults aged 40 years or older, living in rural areas, with no history of cancer or cardiovascular disease (CVD) at baseline. Serum 25-hydroxyvitamin D (25(OH)D) levels were measured at baseline. Participants were followed-up from the survey date (2005-2012) until December 31, 2021. Cox proportional hazards regression was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for mortality by baseline vitamin D level. Restricted cubic splines were used to explore the nonlinearity.

RESULTS

The median (interquartile range) of 25(OH)D level was 55.8 (40.8-71.8) nmol/L. During a median follow-up of 14.3 years, 2250 deaths were recorded. Compared with participants with a 25(OH)D level <30 nmol/L, higher vitamin D levels (30 to < 50, 50 to < 75, and ≥75 nmol/L) were associated with a lower risk of all-cause mortality: HR (95% CI) of 0.82 (0.69-0.98), 0.74 (0.62-0.88), and 0.69 (0.57-0.84), respectively. A nonlinear relationship between vitamin D level and all-cause mortality was observed, with the risk plateauing between 50 and 60 nmol/L (p for nonlinearity = 0.009). The association was more pronounced for cancer-related mortality. HR 0.55 (95% CI: 0.39-0.77) for a 25(OH)D level ≥75 nmol/L compared with <30.0 nmol/L. Low vitamin D levels were associated with increased CVD mortality in men.

CONCLUSIONS

Vitamin D level was inversely associated with all-cause and cause-specific mortality in middle-aged and older adults. Maintaining a serum 25(OH)D level of approximately 50-60 nmol/L may contribute to longevity and warrants further investigation.

Association of serum 25-hydroxyvitamin D concentration with all-cause and cause-specific mortality in hypertensive patients

BACKGROUND AND AIMS

To examine the association of serum 25-hydroxyvitamin D [25(OH)D] with all-cause mortality and disease-specific mortality in patients with hypertension.

METHODS AND RESULTS

This cohort study included US adults in the National Health and Nutrition Examination Survey from 2007 to 2018. All-cause mortality and cause-specific mortality outcomes were determined by association with National Death Index records. Cox proportional risk models were used to estimate hazard ratios (HRs) for all-cause mortality and cause-specific mortality and 95% confidence intervals (CIs) for serum 25(OH)D concentrations. The cohort included 10,325 adult participants. The mean serum 25(OH)D level was 65.87 nmol/L, and 32.2% of patients were vitamin D deficient (<50 nmol/L). During a mean follow-up of 77 months, 1290 deaths were recorded, including 345 cardiovascular deaths and 237 cancer deaths. Patients with higher serum 25(OH)D were more likely to have lower all-cause mortality and cardiovascular mortality than those with serum 25(OH)D < 25.00 nmol/L. For cancer mortality in hypertensive patients, vitamin D may not have a predictive role in this.

CONCLUSIONS

This study shows that higher 25(OH)D levels are significantly associated with lower all-cause mortality and cardiovascular disease (CVD) mortality. These findings suggest that maintaining adequate vitamin D status may reduce the risk of death in patients with hypertension.

Association of serum 25-hydroxyvitamin D concentrations with all-cause and cardiovascular mortality among US adults with prehypertension: a prospective cohort study

BACKGROUND

Prehypertension affects 25-50% of adults worldwide and no prior study has examined the relationship between serum 25-hydroxyvitamin D [25(OH)D] concentrations and mortality risk in individuals with prehypertension. This study aims to investigate the association of serum 25(OH)D concentrations with all-cause and CVD mortality among prehypertensive adults by utilizing data from the US National Health and Nutrition Examination Survey (NHANES) 2007-2014 and linked 2019 mortality file.

METHODS

We included 4345 prehypertensive adults who participated in the NHANES between 2007 and 2014 and were followed up until 31 December 2019. Weighted Cox proportional hazards models were used with adjustments for multiple covariates to calculate the hazard ratio (HR) and 95% confidence interval (CI) for the risks of dying from any cause and CVD.

RESULTS

During a median follow-up of 8.8 years, 335 deaths from any causes were documented, of which 88 participants died from CVD. Compared with participants with sufficient 25(OH)D (≥ 75 nmol/L), the multivariate-adjusted HRs and 95% CIs for participants with severe deficiency (< 25 nmol/L), moderate deficiency (25-49.9 nmol/L), and insufficient concentrations (50-74.9 nmol/L) of serum 25(OH)D for all-cause death were 2.83 (1.46-5.52), 1.17 (0.74-1.86), and 1.36 (0.93-1.98), respectively. Similarly, the multivariable-adjusted HRs and 95%CIs for CVD death were 4.14 (1.10-15.51), 1.23 (0.46-3.28), and 1.73 (0.96-3.14), respectively. We found that there was a 9% reduction in the risk of death from all causes and a 14% reduction in the risk of death from CVD for every 10 nmol/L increase in serum 25(OH)D concentrations.

CONCLUSION

Severe serum 25(OH)D deficiency among prehypertensive adults was associated with increased risk of mortality from all causes as well as from CVD. Our work suggests that supplementing with vitamin D may prevent premature death in severely deficient individuals with prehypertension.

Vitamin D Supplementation and Cardiovascular Disease Risks in More Than 134000 Individuals in 29 Randomized Clinical Trials and 157000 Individuals in 30 Prospective Cohort Studies: An Updated Systematic Review and Meta-analysis

BACKGROUND

According to the findings from observational studies and clinical trials assessing the effect of vitamin D supplements on cardiovascular diseases (CVDs), there are still contradictory results. This systematic review aimed to assess the effect of vitamin D supplements on CVDs considering cohort studies and clinical trials. Study Design: A systematic review.

METHODS

MEDLINE/PubMed, Science Direct, Embase, and Cochrane Library databases were reviewed by two reviewers independently until 2022. The study effect is risk ratio (RR) and 95% confidence interval (CI) according to Mantel Haenszel's random-effects model. Then, Stata version 14 was used for statistical analysis.

RESULTS

In clinical trial studies, the incidence of CVDs among the vitamin D-consuming group was not significantly different from that in the placebo group (RR: 0.99, 95% CI: 0.95-1.03; P=0.77; I 2=0%). CVD mortality was also not significantly different between the two groups (RR: 0.97, 95% CI: 0.90-1.05; P=0.72; I2=0%). In cohort studies, circulating 25 (OH) D increased the risk of CVD incidence by 31% (RR: 1.31, 95% CI: 1.19-1.45) and CVD mortality by 37% (RR: 1.37, 95% CI: 1.17-1.61).

CONCLUSION

According to current evidence from clinical trials, vitamin D supplementation should not be recommended for CVD prevention. However, there is a direct association between vitamin D deficiency and the incidence of CVDs as well as its mortality. According to the results of clinical trial studies carrying higher levels of scientific evidence, it can be concluded that vitamin D supplementation does not exert a significant effect on the incidence, mortality, and reduction of CVDs.

The Effect of Vitamin D Supplementation on the Severity of Symptoms and the Quality of Life in Irritable Bowel Syndrome Patients: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Irritable bowel syndrome (IBS), a gastrointestinal disorder affecting 7-12% of the population, is characterized by abdominal pain, bloating, and alternating bowel patterns. Data on risk and protective influences have yielded conflicting evidence on the effects of alternative interventions, such as vitamin D. This review focuses on the effects of vitamin D on IBS. A systematic review and meta-analysis considered all articles published until 4 April 2022. The search for randomized controlled trials assessing vitamin D efficacy in IBS with outcomes, primary (Irritable Bowel Severity Scoring System (IBS-SSS)) and secondary (IBS quality of life (IBS-QoL) and serum level of calcifediol (25(OH)D)), was performed on six databases, Google Scholar, Web of Science, SCOPUS, EMBASE, PubMed (MEDLINE), and Cochrane Central Register of Controlled Trials. We included six trials with 616 patients. The pooled analysis found no difference between vitamin D and placebo in improving IBS-SSS (MD: -45.82 with 95% CI [-93.62, 1.98], p = 0.06). However, the pooled analysis favored vitamin D over placebo in improving the IBS-Qol (MD: 6.19 with 95% CI [0.35, 12.03], p = 0.04) and serum 25(OH)D (MD: 25.2 with 95% CI [18.41, 31.98], p = 0.00001). Therefore, further clinical trials are required to reach clinically applicable and generalizable findings.