Key Takeaways:
- Calcium and vitamin D supplementation led to reductions in systolic and diastolic blood pressure (BP) in all study participants.
- Participants with obesity experienced the greatest BP reductions.
- Higher doses of vitamin D did not provide additional benefits beyond the standard recommended dose.
Summary
A post hoc analysis published in the Journal of the Endocrine Society found that vitamin D and calcium supplementation significantly reduced BP in older adults with overweight or obesity, particularly those with hypertension. However, higher doses of vitamin D did not yield greater benefits.
Study Design:
- Researchers analyzed data from a completed double-blind, randomized controlled trial involving 221 older adults (mean age: 71.1 years; mean BMI: 30.2 kg/m²) with vitamin D deficiency and a BMI greater than 25 kg/m².
- Participants were randomized to receive either a low dose (600 IU/day) or high dose (3,750 IU/day) of vitamin D3, alongside 1,000 mg of elemental calcium daily, for one year.
- BP measurements were taken every three months.
Findings:
- Overall BP Reductions:
- At 1 year, systolic BP decreased by 3.5 mm Hg (P = .005) across all participants, with a 4.2 mm Hg reduction (P = .023) in the high-dose group. The low-dose group experienced a nonsignificant 2.8 mm Hg decrease.
- Diastolic BP decreased modestly by 2.8 mm Hg (P = .002) overall, with a 3.02 mm Hg reduction (P = .01) in the high-dose group, and a nonsignificant 2.6 mm Hg reduction in the low-dose group.
- Impact of BMI:
- Participants with a BMI over 30 kg/m² showed significant decreases in systolic BP in both dosage groups. Diastolic BP significantly decreased only in the high-dose group.
- Hypertension Subgroup:
- Among participants with hypertension, both systolic and diastolic BP decreased significantly over time, regardless of BMI.
- Predictors of BP Reduction:
- Baseline BMI (beta = 0.29; P = .05) and systolic BP (beta = 0.16; P < .001) were predictors of BP reduction at 6 and 12 months, while vitamin D dose was not a significant factor.
Limitations:
- The study had limited data on participants’ physical activity levels.
- The exploratory nature and low power of subgroup analyses may limit the generalizability of findings.
Conclusion:
The results underscore the role of demographic and health factors, such as age and obesity, in influencing the effects of vitamin D on BP. While supplementation with vitamin D and calcium appears to lower BP, the benefits of higher vitamin D doses remain unclear. Further patient-level meta-analyses are needed to confirm these findings and determine the optimal vitamin D dosage for BP management.
