Vitamin D is commonly called the “sunshine vitamin” because our skin naturally makes it when it’s exposed to the ultraviolet B rays found in sunlight. Yet, even during the summer months, heart failure patients are often deficient in this vitamin. Seeking to resolve this issue, a new five-year study investigated the potential benefits heart patients experience when they take vitamin supplements — it found some surprising results.

A daily dose of vitamin D3 improved heart function in people with heart muscle weakness, said the University of Leeds researchers, led by Dr. Klaus K. Witte, a senior lecturer in cardiology. While patients who took placebos saw no changes, those who received vitamin supplements experienced up to a 34-percent improvement in heart pumping function.

Vitamin D deficiency is common among older adults, who make less compared to younger people when exposed to the sun. Sunscreen also reduces vitamin D production in the skin and few foods naturally contain it, so people who are deficient may need supplements, which usually come in two forms: vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol).

“Vitamin D3 is more reliable and potent [than Vitamin D2],” Witte told Medical Daily. Though both types must undergo chemical conversion inside your body, Vitamin D3 is the type that’s made in your skin.

Generally, one of the best known benefits of vitamin D is its ability to improve bone and musculoskeletal health. By contrast, deficiency causes osteopenia (weak bones) and intensifies osteoporosis (decreased bone density causing brittle bones) — both increase the risk of falls and fractures. Insufficient vitamin D has also been linked to dementia and chronic heart failure — hence the researchers’ study.

With regard to heart problems, “the severity of the deficiency relates to the levels of symptoms, exercise capacity, diuretic requirements, and response to optimal medical therapy,” wrote Witte and his colleagues, noting that it’s unclear whether this deficiency is a symptom or cause of heart disease.

To learn whether vitamin D supplements might benefit heart failure patients, Witte and his colleagues designed the Vitamin D Treating Patients with Chronic Heart Failure (VINDICATE) study. In particular, they focused on patients with left ventricular systolic dysfunction, where the heart does a poor job of pumping blood out to the body.


Heart failure affects more than 23 million people worldwide and more than more than half are over the age of 75. Even when they receive optimal care, patients often suffer a poor quality of life, with persistent symptoms and hospitalizations.

The VINDICATE study involved 163 patients already being treated for heart failure using a proven and accepted treatment, including beta-blockers, ACE-inhibitors, and pacemakers. The researchers assigned study participants to take either vitamin D3 — though not a calcium-based product, which could harm heart failure patients — or placebo pills for one year. To measure potential changes in heart function, they used a technique known as ejection fraction, which involves scanning the heart with an echocardiogram and measuring how much blood pumps away from the heart with each beat.

In healthy people, the ejection fraction is usually between 60 and 70 percent. For the VINDICATE patients, the average ejection fraction was just 26 percent before the study began.

So what happened after a year on either vitamin D or placebo?

Patients taking vitamin D3 experienced an improvement in heart function, while the placebo patients remained unchanged. Patients taking vitamin D3 saw their heart pumping function improve by 8 percent, rising to 34 percent.

Witte and his co-authors say this represents a significant breakthrough for patients. Most importantly, vitamin D3 supplements may prevent some patients from needing an implantable cardioverter defibrillator device, which can detect irregular heart rhythms and shock the heart to restore normal rhythm. These devices are not only expensive, they also involve surgery, a risk most older people prefer not to take.

Source: Witte K, Gierula J, Paton MF et al. Vitamin D Supplementation Improves Cardiac Function in Patients with Chronic Heart Failure. American College of Cardiology 65th Annual Scientific Session. 2016.