Effect of Monthly, High-Dose, Long-Term Vitamin D Supplementation on Central Blood Pressure Parameters: A Randomized Control Trial

 

Vitamin D title

This study was published in the Journal of the American Heart Association (JAHA)

Vitamin D is important for numerous cell processes as well as optimal function and performance. Learn about many of the effects of vitamin D/vitamin D deficiency in the vitamin D infograph. 

What’s new in this study:

  • One of few randomized control trials using vitamin D supplementation using a unique monthly, high dose supplement over the span of 1 year in a population-based sample
  • Novel central blood pressure measurements rather than more traditional brachial blood pressure measurements
  • First study to show a reduction in central blood pressure parameters in vitamin D deficient people with vitamin D supplementation
  • Unique effects of vitamin D shown through factor analysis: decreased maximal blood pressure and pulse rate-related augmentation of the aortic pressure waveform.

Background

  • Low levels of vitamin D (25[OH]D) (the precursor to the active form of Vitamin-D) have been associated with increased risk of Cardiovascular disease mortality, hypertension, and arterial stiffness
  • However, a causal relationship between Vitamin-D and CVD has not been established, but may involve other lifestyle factors that cannot be controlled for in observational studies (nutrition, lifestyle, etc)
  • Few controlled trials have shown benefits associated with Vitamin-D supplementation
  • Lack of results may be due to
    • small sample sizes
    • low-dose of vitamin D used
    • short duration of supplementation
    • single measures (i.e brachial blood pressure) as only outcome
  • As of yet, whether or not vitamin-D supplementation improves cardiac function is unclear

Participants

  • 517 adults 50-84 years of age

Intervention

Study participants were randomized to one of the following groups for the entire study duration (1.1 year)

  • Initial dose of Vitamin D3 200,000 IU + 100,000 IU doses every month thereafter
  • Placebo pill monthly

Results

  • Vitamin D (25[OH]D) concentrations increased in the supplemented group (66nmol/L to 122nmol/L)
  • No change in vitamin D concentrations in the placebo group (expected)
  • No change in central BP or vascular parameters observed in the study cohort- however, a subset of 150 individuals who were identified as Vitamin-D deficient (pre-study) were reanalyzed
  • Vitamin D deficient individuals receiving the supplement demonstrated
    • Decrease in brachial systolic blood pressure
    • decrease in brachial diastolic blood pressure
    • Decrease in aortic systolic blood pressure
    • Lower augmentation index, a measure of arterial stiffness
    • Lower pulse wave velocity, a measure of arterial stiffness
    • Lower reservoir pressure in the heart
    • Lower backwards pressure amplitude

Conclusions and clinical perspective

Results of this study indicate that a monthly high-dose vitamin D supplement may lower central blood pressure parameters, however, this effect is seen only in individuals with vitamin D deficiency – thus, future supplementation trials should focus on vitamin D deficient groups.

In this study, brachial BP was not affected in total study population, while central parameters were lowered. Therefore, future studies assessing the effects of vitamin D supplementation should analyze central BP parameters to capture efficacy of this treatment.

Even thought a sizable and presumably beneficial improvement in central BP parameters in vitamin D deficient adults was seen, future clinical trials should seek to confirm whether effects translate into a reduction in cardiovascular morbidity and mortality.

Citation: J Am Heart Assoc. 2017;6:e006802; originally published October 24, 2017;

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