July 5, 2023 – A new study suggests that taking a monthly, high-dose vitamin D supplement could, over the long term, lead to a small improvement in the risk of a heart attack.
Researchers in Australia randomly assigned more than 20,000 adults, ages 60 to 84, to take one 60,000-IU dose of vitamin D3 or a placebo capsule every month for 5 years.
Over the course of the study, 6% of subjects taking vitamin D and 6.6% of those given the dummy supplement had a major cardiovascular event such heart attack or stroke. That meant 5.8 fewer events for every 1,000 people on vitamin D.
There were signs that people who started the trial while taking statins or other heart medications may have had a stronger benefit, but more research would be needed to confirm that possibility, said Rachel Neale, PhD, a professor at QIMR Berghofer Medical Research Institute in Queensland, Australia. She is senior author on the study's report that was published online June 28 in The BMJ.
Vitamin D is made naturally by skin exposed to sunlight, so many people make enough and don’t need to take a supplement, she explained. But a vitamin D supplement can help avoid a deficiency in those who get limited sun. Although the vitamin was given in high once-monthly doses, daily dosing is likely to be more helpful, Neale said.
“If you want to take a supplement, I would recommend a daily dose of not more than 2,000 IU," she said.
The study's results could have been due to chance, so it's "premature” for doctors to recommend vitamin D supplements to prevent cardiovascular disease, cautioned Nour Makarem, PhD, an assistant professor of epidemiology in the Mailman School of Public Health at Columbia University in New York City.
“If you’re over age 60, you should not take a vitamin D supplement solely because of the results of this study,” she said. Such decisions, and the right dose, should be discussed with one's health care provider, "taking into consideration your medical history and health status," she said.