Vitamin D Supplements May Protect Against Heart Disease - Everyday Health

High-dose vitamin D supplements taken once a month may lower the likelihood of heart attack or other major cardiac events in people ages 60 and up, according to a large new study published this week in The BMJ.

Although the level of risk reduction was small, researchers discovered that vitamin D supplementation may cut the incidence of heart attack and the need for coronary revascularization (procedures which restore blood flow to areas of your heart that aren't getting enough blood).

Does Vitamin D Actually Offer Any Heart-Protective Benefits?

So far, research on the heart benefits of vitamin D have been mixed. Study authors mentioned that some previous trials have indicated that supplementation does not prevent heart trouble.

A analysis published in 2019 in JAMA Cardiology, which included 21 clinical trials and more than 83,000 participants, concluded that vitamin D supplements do not reduce the risk of having or dying from a heart attack or stroke.

"These [latest] findings suggest that conclusions that vitamin D supplementation does not alter the risk of cardiovascular disease are premature," wrote Rachel Neale, PhD, deputy coordinator of the population health department at the QIMR Berghofer Medical Research Institute in Queensland, Australia, and her study coauthors.

"These findings could prompt further evaluation of the role of vitamin D supplementation, particularly in people taking drugs for prevention or treatment of cardiovascular disease," they added.

Large Trial Suggests Some Heart Benefits From Vitamin D

The analysis involved more than 21,000 people ages 60 to 84 who were divided into two groups: one receiving a monthly capsule of 60,000 IU (international units) of vitamin D and one receiving a placebo.

The study excluded those already taking more than 500 IU of vitamin D per day, as well as individuals with a history of high calcium levels, hyperparathyroidism, kidney stones, soft bones osteomalacia, and sarcoidosis (a disease characterized by the growth of tiny collections of inflammatory cells).

On average, treatment lasted for five years and more than 80 percent of participants reported taking at least 80 percent of the study tablets.

During the trial, 1,336 participants experienced a major heart problem (6.6 percent in the placebo group versus 6 percent in the vitamin D group).

While the difference between the two groups was relatively small, the rate of major cardiovascular events was 9 percent lower for those taking vitamin D compared with those getting a placebo (equivalent to 5.8 fewer events per 1,000 participants).

The rate of heart attack was 19 percent lower and the rate of coronary revascularization was 11 percent lower in the vitamin D group. When it came to stroke, though, there was no difference between the two groups.

"Overall, the effect of the dose given to this population was small," says Anastassios G. Pittas, MD, chief of the division of endocrinology at Tufts Medical Center in Boston. "But then if you consider the low costs [20 cents per tablet or less] and overall safety, and you apply this at the large public health level, it may have important implications."

Dr. Pittas notes that in this study, 6 out of 1,000 cardiovascular events could be prevented with vitamin D, while in general, a threshold for a minimally important difference in reduction is 20 or 30 fewer per 1,000.

In a subgroup analysis, researchers saw some indication of a stronger effect in those who were using statins or other cardiovascular drugs at the start of the trial.

While the researchers said these results were not statistically significant, Pittas called the effect in this population "interesting."

"People who take statins and cardiovascular drugs are at higher risk for developing cardiovascular disease," he says." I think you might argue that people who are at risk may benefit the most from the intervention."

Why Was Such High Dose of Vitamin D Necessary?

The 60,000 IU dose used in this study is considered high. Mayo Clinic says that the recommended daily amount for older adults is between 600 and 800 IU (or up to 24,000 IU monthly).

The investigators made the choice to give the dose monthly to improve adherence. If you only have to do something once a month versus every day, adherence may improve.

The researchers also wanted to gauge what would happen to people if their vitamin D intake was pushed beyond the recommended range.

"When we're trying to prevent a specific condition such as cardiovascular disease or diabetes, then we may need to give more than the typical dose of vitamin D," says Pittas. "In general, however, it is believed that it is better to take vitamin D daily than nondaily, as constant exposure to moderate doses is thought to be more physiologic than intermittent exposure to high doses."

Still, too much of a good thing may do damage. According to Mayo Clinic, taking 60,000 IU of vitamin D daily for several months has been shown to cause toxicity.

Ultimately, Pittas stresses that it's not possible to draw any general conclusions about vitamin D and the general population from this single study. The benefit-to-risk ratio for vitamin D depends on the target population, their medical condition, and the distinction between "treatment" and "supplementation," according to Pittas.

Recognizing Vitamin D Deficiency

While some people can get sufficient vitamin D from natural sources — such as specific foods, according to the Harvard T.H. Chan School of Public Health, and sunlight, per UCLA Health — the National Institutes of Health estimates that about 1 in 4 U.S. adults are not getting enough.

The University of Nebraska-Lincoln lists the following symptoms as possible signs of vitamin D deficiency, and urges those having symptoms to contact their doctor:

• Fatigue
• Not sleeping well
• Bone pain or achiness
• Depression or feelings of sadness
• Hair loss
• Muscle weakness
• Loss of appetite
• Getting sick more easily
• Pale skin

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