A new clinical trial published in the Pakistan Journal of Medical Sciences found that vitamin D may improve the severity of heart failure.
Heart failure (HF) occurs when the heart cannot pump enough blood to the body. This results in a diminished quality of life due to frailty, muscle weakness, shortness of breath and death.
Nearly 5 million Americans currently live with HF. Despite the increase in understanding of HF, the prognosis of HF remains poor with only a 35% chance of surviving five years after diagnosis.
Researchers have expressed an interest in vitamin D and HF, because HF patients tend to have lower vitamin D levels compared to healthy adults. Furthermore, low vitamin D levels can cause muscle weakness, potentially exacerbating patients’ HF symptoms.
A previous open label trial found that vitamin D supplementation helped heart failure severity. To evaluate these findings, researchers conducted a recent non-randomized clinical trial.
The trial included 43 patients with HF who were not showing any signs of improvement in physical performance despite using medication. All patients had vitamin D levels below 30 ng/ml.
The patients received 200,000 IU of vitamin D on a weekly basis for 12 weeks in addition to their standard heart failure treatment. The researchers evaluated the success of vitamin D supplementation by measuring 6 minutes’ walk distance and Pro-BNP level.
The six-minute walk test measures the distance an individual can walk on a hard, flat surface within six minutes. The test assesses one’s physical fitness. Pro-BNP are substances that are produced in the heart when it is working very hard. Therefore, high a pro-BNP level indicates a greater severity of HF.
Here is what he researchers found:
- Average vitamin D levels increased significantly from 16.59 ng/ml at the beginning of the study to 31.97 ng/ml after 12 weeks (p < 0.0005).
- The average six minute walk distance significantly increased after vitamin D supplementation from 806 feet before supplementation to 945 after supplementation (p = 0.008).
- The average pro-BNP level of the patients was 1024 before the study and improved to 149 after supplementation (p < 0.0005).
The researchers concluded,
“Vitamin D supplementation decreases the severity of HF as reflected by reduction in serum pro-BNP levels and significant increase in six minutes’ walk distance.”
The results present HF patients with further hope that they can improve their physical fitness, and thus, quality of life through a simple and affordable treatment, vitamin D. As a clinical trial, it possessed a few important strengths. First, the study proved a causal relationship between vitamin D and HF, meaning vitamin D supplementation caused significant improvements in severity of HF. This vastly differs from a study that only proves association. Also, all patients were vitamin D deficient at baseline and were given an adequate dose for most to significantly increase their vitamin D levels. This allows researchers to properly assess the benefits of vitamin D supplementation opposed to if they enrolled patients who already had healthy vitamin D levels.
However, it’s important to acknowledge the study’s major limitation, a lack of control group. Unfortunately, the study did not include a group that did not receive vitamin D. Without a control group, researchers cannot account for placebo effect, or the beneficial effect that is not attributed to the treatment itself but rather due to the patient’s belief in that treatment. In addition, the study consisted of a very small sample size.
This study warrants randomized controlled trials to further investigate the benefits of high dose vitamin D supplementation for HF patients.
Tovey, A. & Cannell, JJ. Clinical trial finds vitamin D may reduce severity of heart failure. The Vitamin D Council Blog & Newsletter, 2017.