People who have cardiovascular disease (CVD) can reduce their risk of death by almost a third simply by maintaining normal vitamin D levels. This is the finding of a new study recently published in The Journal of Clinical Endocrinology & Metabolism.

CVD is an umbrella term for conditions that affect the heart and blood vessels, including heart disease, heart attack, heart failure, and stroke.

CVD is the number 1 killer in the United States. Heart disease alone is responsible for around 610,000 deaths in the country every year.

Previous research suggests that vitamin D status may play an important role in cardiovascular health.

A study reported in 2016, for example, associated low vitamin D levels with greater risk of stroke, heart failure, heart attack, and cardiovascular death.

The new study—led by Professor Jutta Dierkes, of the Department of Clinical Medicine at the University of Bergen in Norway—further investigated the role that vitamin D levels play in the risk of death from CVD.

CVD mortality reduced by 30%

In order to reach their findings, Professor Dierkes and colleagues analyzed the blood samples of 4,114 adults who had suspected angina pectoris, which is chest pain as a result of coronary heart disease.

Subjects were an average age of 62 at study baseline, and they were followed up for an average of 12 years.

The team assessed the subjects' blood samples for levels of 25-hydroxyvitamin D3, or 25(OH)D, which is the primary circulating form of vitamin D. During follow-up, there were a total of 895 deaths. Of these, 407 were related to CVD.

According to the National Institutes of Health (NIH), a 25(OH)D level of 50–125 nanomoles per liter (nmol/l) is "generally considered adequate for bone and overall health in healthy individuals."

In the study, the researchers found that the optimal 25(OH)D blood concentrations for mortality risk were 42–100 nmol/l. Concentrations lower than 42 nmol/l and higher than 100 nmol/l were associated with a greater risk of death from CVD.

In fact, the researchers found that participants with the optimal 25(OH)D concentrations were 30% less likely to die of CVD.

"We discovered," says Professor Dierkes, "that the right amount of vitamin D reduces the risk of death substantially. However, too much or too little increase the risk."

Based on these results, Professor Dierkes recommends that all people with CVD have their vitamin D levels measured and monitored. If levels are below normal, vitamin D supplementation might be required.

That said, the researchers note that the optimal amount of vitamin D is not the same for everyone. "It depends where you live, and what kind of diet you have," Professor Dierkes adds.

The primary source of vitamin D is sunlight, but we can also get it from certain foods—including salmon, tuna, and eggs—and dietary supplements, which are available to purchase online.

However, it is worth noting that further studies are needed before vitamin D can be recommended as a beneficial supplement for people with CVD.