BACKGROUND AND PURPOSE:

• Thomson et al. (Annals of Internal Medicine, 2024) evaluated long-term health outcomes related to calcium and vitamin D (CaD) intake among postmenopausal women

METHODS:

• Post hoc analysis of long-term, postintervention follow-up of an RCT
  • Women’s Health Initiative 7-year CaD trial
• Participants
  • Postmenopausal women
  • No history of breast or colorectal cancer
• Intervention
  • 1000 mg of calcium carbonate (400 mg of elemental calcium) with 400 IU of vitamin D3 daily
  • Placebo
• Study design
  • Analyses stratified based on prerandomization supplement use 
• Primary outcome
  • Incidence of colorectal, invasive breast, and total cancer
  • Disease-specific and all-cause mortality
  • Total cardiovascular disease (CVD)
  • Hip fracture by randomization assignment

RESULTS:

• 36,282 women
  • Median cumulative follow-up: 22.3 years
• CaD supplementation was associated with a
  • 7% reduction in cancer mortality
    • Hazard ratio (HR) 0.93 (95% CI, 0.87 to 0.99)
  • 6% increase in CVD mortality
    • HR 1.06 (95% CI, 1.01 to 1.12)
• There was no overall effect on other measures
  • E.g., all-cause mortality: HR 1.00 (95% CI, 0.97 to 1.03)
• Estimates for cancer incidence varied widely when stratified by whether participants reported supplement use before randomization
• Estimates on mortality generally did not vary
• Analyses of hip fracture outcomes were limited due to samples size

CONCLUSION:

• After 20 years of follow-up, CaD supplementation among postmenopausal women was associated with a slight reduction in cancer mortality and a slight increase in CVD mortality
• Long-term, all-cause mortality was not impacted by CaD supplementation
• The authors state

Given the study design, we could not disentangle the added benefit or harms of supplementation with CaD in combination versus vitamin D alone, a topic worthy of future study

Learn More – Primary Sources:

Long-Term Effect of Randomization to Calcium and Vitamin D Supplementation on Health in Older Women: Postintervention Follow-up of a Randomized Clinical Trial