Vitamin D is important for healthy bones, muscles, and the immune system.
Low levels are common in older adults, and many studies have also found that people with low vitamin D are more likely to develop cardiovascular disease.
Cardiovascular disease includes problems such as heart attacks, heart failure, and stroke. It is especially important in older people because it remains a leading cause of illness and death among adults over 65.
The connection between low vitamin D and heart disease has raised an obvious question: could taking more vitamin D protect the heart? A study from Beth Israel Deaconess Medical Center suggests the answer may be no, at least for older adults with low vitamin D levels.
The researchers used information from a large clinical trial called the Study to Understand Fall Reduction and Vitamin D in You, or STURDY. The trial included adults aged 70 and older who had relatively low levels of vitamin D in their blood.
Participants received different daily doses of vitamin D3. The doses were 200, 1,000, 2,000, or 4,000 international units, commonly called IU.
The original trial was designed mainly to investigate whether vitamin D could reduce falls. For the new analysis, researchers focused instead on signs of stress or damage to the heart.
They measured two proteins in participants’ blood that doctors and researchers use as indicators of heart health. Higher levels of these proteins can be associated with strain on the heart muscle or injury to heart cells.
Blood samples were collected at the beginning of the study and again during roughly two years of follow-up. This allowed the researchers to see whether taking larger amounts of vitamin D caused these heart-related markers to fall over time.
At the start, lower vitamin D levels were associated with higher levels of one of the heart markers. That finding was consistent with earlier research showing a connection between vitamin D deficiency and poorer cardiovascular health.
But increasing vitamin D intake did not improve the heart markers. Participants taking higher doses did not show meaningful reductions compared with those taking the lowest dose.
The same general result appeared across different groups of participants. Age, sex, race, and conditions such as high blood pressure or diabetes did not substantially change the findings.
This distinction is important because an association does not necessarily mean that one thing causes another. People with low vitamin D may have other characteristics that increase heart disease risk, rather than low vitamin D itself being the direct cause.
For example, people who spend less time outdoors may have lower vitamin D because sunlight helps the skin produce it. They may also be less physically active, and regular physical activity is already known to be important for cardiovascular health.
Lead author Dr. Katharine W. Rainer and colleagues said the results provide further evidence that simply increasing vitamin D intake is unlikely to prevent cardiovascular disease. Senior author Dr. Stephen P. Juraschek noted that other factors linked with low vitamin D may better explain its connection with heart risk.
The study was published in the American Journal of Preventive Cardiology. While vitamin D remains important for health and supplements may be recommended for people who need them, the findings suggest that taking higher doses should not be viewed as a proven way to protect the heart.
If you care about heart health, please read studies about how eating eggs can help reduce heart disease risk, and Vitamin K2 could help reduce heart disease risk.
For more health information, please see recent studies that olive oil may help you live longer, and Vitamin C linked to lower risk of heart failure.
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