An Empirical Study on the Effect of Short-Term Regular Vitamin D3 Supplement Therapy on Blood Pressure and Exercise Tolerance in Heart Failure Patients

The receptor of vitamin D is expressed in almost all body cells, including vascular endothelial cells and cardiomyocytes. Vitamin D deficiency has been observed widespread amongst heart failure (HF) patients, which could have harmful effects on their health condition. This study aims to investigate the effect of vitamin D supplements on blood pressure (BP) and physical activity of HF patients. Thirty-nine systolic HF patients with low ejection fraction (EF) < 50% and class III of New York Heart Association functional classification were randomly divided into 2 groups including intervention and placebo to enroll in an 8 weeks double-blind clinical trial. During the trial 6-minute walk test (6MWT), 25-hydroxyvitamin D (25[OH]D) level, BP, sodium and potassium intakes were assessed. The mean 25(OH)D level increased to 28.9 ± 11.7 ng/mL (p < 0.001) in the intervention group. There was a poor but non-significant reduction in systolic BP (−0.033 ± 4.71 mmHg, p = 0.531) in the intervention group. The BP also did not change in the placebo group at the end of the trial. A negligible decrease of 6MWT was observed in the intervention group (−6.6 ± 29.2 m) compared to the placebo (−14.1 ± 40.5 m). However, differences between the 2 groups were not statistically significant (p = 0.325). The results solely showed a slight positive correlation between 25(OH)D level and 6MWT. No significant improvements in BP and 6MWT were observed after vitamin D3 supplementation. TRIAL REGISTRATION: Iranian Registry of Clinical Trials Identifier: IRCT2016102113678N13