Not only are low levels of vitamin D linked to coronary artery disease (CAD), heart attack and stroke, but a new study reveals what specific level of deficiency may raise risk for these conditions. As we recently reported, up to 75 percent of Americans are low in vitamin D, “the sunshine vitamin”.
The study found that that patients with blood levels of vitamin D of less than 15 nanograms per milliliter (ng/ml) had a significantly higher rate of major cardiovascular events – such as heart attack, stroke, CAD, heart failure and death – compared to those with higher levels.
“Although vitamin D levels above 30 were traditionally considered to be normal, more recently, some researchers have proposed that anything above 15 was a safe level. But the numbers hadn’t been backed up with research until now,” said J. Brent Muhlestein, MD, co-director of cardiovascular research at the Intermountain Medical Center Heart Institute and lead investigator of the study.
Millions of Americans Have Vitamin D Levels Linked to Cardiac Risk
“Even if any level above 15 is safe, one out of 10 people still have vitamin D levels lower than that,” added Dr. Muhlestein. “This equates to a very large percentage of our population.” Vitamin D levels can be checked with a simple blood test.
The study, which was presented at the 2015 American Heart Association (AHA) Scientific Sessions, included more than 230,000 patients who were divided into four groups based on their blood levels of vitamin D (less than 15 ng/ml, 15-29, 30-44, and 45 or higher).
During three years of follow-up, participants with vitamin D levels of less than 15 ng/ml had a 35 percent higher risk for major or fatal cardiac events, compared to the other three groups. No significant differences in risk were observed in the three groups with vitamin D levels of 15 ng/ml or higher.
“This study sheds new light and direction on which patients might best benefit from taking vitamin D supplements,” said Dr. Muhlestein. “Even though there’s a possibility that patients may benefit in some way from achieving higher blood levels of vitamin D, this new information tells us the greatest benefit to the heart will likely occur among patients whose vitamin D level is below 15 ng/ml.”
Study findings presented at medical meetings are considered preliminary until the research is published in a peer-reviewed journal.
Four Surprising Discoveries About Vitamin D and Heart Health
The study adds to other recent findings about the effects of vitamin D levels on cardiovascular health and risk for heart attack and stroke, including the following:
- Low vitamin D may be an independent risk for heart attacks and strokes. Data from dozens of studies over the past 30 years is now so robust that a 2014 comprehensive review concludes that vitamin D deficiency meets established scientific standards as a “causal” risk factor for cardiovascular disease (CVD), the leading killer of American men and women, often from heart attacks and strokes.
- Vitamin D protects heart health by fighting inflammation. The 2014 meta-analysis found that vitamin D supplementation can significantly improve levels of the inflammatory marker high-sensitivity C-reactive protein (hsCRP). Other research suggests that apparently healthy people with high hsCRP levels are up to four times more likely to have CAD and also face increased risk for heart attack, stroke, and death from cardiovascular causes. Simple blood and urine tests to measure levels of inflammatory biomarkers can help practitioners evaluate a patient’s cardiovascular risk.
- Vitamin D deficiency is linked to more severe heart disease. In a 2014 study of nearly 1,500 people undergoing angiography, nearly 70 percent of participants were low in vitamin D. The study found that those with vitamin D “levels low enough to be considered deficient had almost a 20% greater risk of the most severe level of the disease.” The research was published in European Journal of Clinical Investigation.
- Targeting both high cholesterol and inflammation may improve heart disease prevention. According to Peter Libby, MD, internationally renowned for his CVD research and recently published in Cardiology, “In an era of precision medicine, the ability to target either LDL or inflammation, or both, depending on an individual’s biomarker profile, should allow us to personalize therapy in the secondary prevention of coronary heart disease.” About 50 percent of heart attacks and strokes occur in people with “normal” cholesterol. As we recently reported, studies suggest that inflammation explains this residual risk, both by contributing to formation of vulnerable plaque and to its rupture, which can spark a heart attack or stroke.