Heart Attack Risk Halved in Survivors Taking Tailored Vitamin D Doses, Researchers Say

The paper released this month adds to a growing body of research around vitamin D supplementation and heart disease.

A man sits in a hospital waiting room in Irvine, Calif., on July 8, 2025. John Fredricks/The Epoch Times

Researchers found that adult heart attack survivors who took specific vitamin D doses reduced their risk of developing another heart attack by more than half, compared with people who did not take the vitamin D dose.

Research conducted by Utah-based Intermountain Health found that there was a 52 percent lower risk of suffering another heart attack in people who had already survived one and who had received “personalized dosing of vitamin D supplements” to reach vitamin D levels of 40 nanograms per milliliter (ng/ml) for about four years, a statement from the American Heart Association (AHA) reads.

That was compared with those who did not receive management of their vitamin D levels, the AHA stated.

More than 85 percent of the people who enrolled in the study had vitamin D levels below the 40 ng/ml threshold, while nearly 52 percent in the study group had to take more than 5,000 international units (IU) of vitamin D per day to reach the blood target levels, the Nov. 9 release states. The 5,000 IU dose is about six times the 800 IU per day that is recommended by the Food and Drug Administration.

“Previous clinical trial research on vitamin D tested the potential impact of the same vitamin D dose for all participants without checking their blood levels first,” Heidi T. May of Intermountain Health said in an AHA statement.

The researchers also checked the study participants’ vitamin D levels when they started the study. Later, they followed up, adjusting the dose as needed to reach a range of between 40 ng/ml and 80 ng/ml, according to the statement.

The authors of the paper suggested that their findings could allow health care providers to focus more on blood testing for people who had experienced heart attacks and to provide tailored doses for them.

Although the AHA did not say what form of vitamin D was administered in the study, a separate statement issued by Intermountain Health said the researchers used vitamin D3, the most common form used in dietary supplements.

In the statement, May said the researchers “observed no adverse outcomes when giving patients higher doses of vitamin D3 supplementation” and that the supplements “significantly [reduced] the risk of another heart attack.”

“[These are] exciting results,” she said in the statement.

The study was presented at the AHA Scientific Sessions 2025 in New Orleans earlier in November. It enrolled 630 adults with acute coronary syndrome who were treated at the Intermountain Medical Center in Salt Lake City from April 2017 to May 2023 and who had an average follow-up of 4.2 years for their condition.

The AHA stated that about 107 major cardiac events such as heart attacks, strokes, heart failures that required hospitalization, and deaths occurred during the study period.

The paper released this month adds to a growing body of research on vitamin D supplementation and heart disease. In 2024, a study found that taking vitamin D supplements doesn’t reduce the risk of cardiac arrest in older adults, while one published in the British Medical Journal showed that there was an association between the supplements and major cardiac events among people older than 60.

Aside from supplements, foods that are considered rich in vitamin D include egg yolks, fatty fish, fish liver oil, and cheese, while some foods such as cereal, orange juice, milk, and others are fortified with the vitamin. Vitamin D is also activated in the body when the skin is exposed to sunlight.

May said her organization is encouraging those who have heart disease to speak to health care providers about targeted vitamin D dosing.