BACKGROUND AND PURPOSE:

• Previous observational studies suggest an association between low serum vitamin D levels and an increased risk of cardiovascular disease (CVD)
  • Limitations based on study design include lack of causational evidence due to possible confounding
• Barbarawi et al (JAMA Cardiolology, 2019) examined whether vitamin D supplementation reduced CVD events and all-cause mortality

METHODS:

• Systematic review and meta-analysis
• Inclusion criteria
  • RCTs
  • Results included ≥1 year (long-term) vitamin D supplementation on CVD events and all-cause mortality
• Data analysis
  • Random-effects models were used to report risk ratio (RRs) and 95% CIs
• Primary outcome
  • Major adverse cardiovascular events
• Secondary outcomes
  • Myocardial infarction
  • Stroke or cerebrovascular accident
  • CVD mortality
  • All-cause mortality

RESULTS:

• 21 RCTs | 83,291 patients
  • 41,699 received vitamin D | 41,622 received placebo
  • Mean (SD) age of trial participants: 65.8 (8.4) years
  • 74.4% were female
• Vitamin D supplementation, compared to placebo was not associated with reduced risk of
  • Major adverse cardiovascular events: RR 1.00 (95% CI, 0.95-1.06; P = .85)
  • Myocardial infarction: RR 1.00 (95% CI, 0.93-1.08; P = .92)
  • Stroke: RR 1.06 (95% CI, 0.98-1.15; P = .16)
  • CVD mortality: RR 0.98 (95% CI, 0.90-1.07; P = .68)
  • All-cause mortality (RR 0.97 (95% CI, 0.93-1.02; P = .23)
• Results were not impacted by the following
  • Sex
  • Baseline 25-hydroxyvitamin D level
  • Vitamin D dosage
  • Formulation (daily vs bolus dosing)
  • Presence or absence of concurrent calcium administration

CONCLUSION:

• Authors acknowledge limitations of this study
  • Most studies did not include prespecified CVD as endpoint | Underpowered for some CVD events | Heart failure generally not included
• While additional larger trials would be necessary to address the above issues, the authors conclude that

… included trials, although different in their inclusion criteria, showed consistent findings of no significant benefit of vitamin D supplementation in reducing CVD events and all-cause mortality

Learn More – Primary Sources:

Vitamin D Supplementation and Cardiovascular Disease Risks in More Than 83,000 Individuals in 21 Randomized Clinical Trials: A Meta-analysis

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