A new study reveals that a personalized, monitored approach to vitamin D3 supplementation after a heart attack can dramatically cut the risk of a second heart attack.
A new study from heart specialists at Intermountain Health in Salt Lake City reports that a personalized method of vitamin D3 supplementation can greatly lower the chances of a second heart attack in patients who have already experienced one.
In a large randomized clinical trial, researchers discovered that using a “target to treat” strategy—where patients’ vitamin D levels were routinely measured and supplement doses were adjusted to reach an optimal range—cut the risk of another heart attack by 50 percent.
The findings were recently unveiled at the 2025 American Heart Association Scientific Sessions in New Orleans.
The results are promising, said Heidi May, PhD, cardiovascular epidemiologist at Intermountain Health and principal investigator of the study
“We observed no adverse outcomes when giving patients higher doses of vitamin D3 supplementation, and to significantly reduce the risk of another heart attack, which are exciting results,” said Dr. May. “We’re excited with these results but know we have further work to do to validate these findings.”
This research carries broad significance, as an estimated one-half to two-thirds of the global population has insufficient levels of vitamin D.
Changing Lifestyles and Vitamin D Deficiency
In the past, people typically received sufficient vitamin D through regular sunlight exposure. Today, lifestyle changes and medical advice aimed at reducing skin cancer risk have led many to spend less time in the sun. As a result, maintaining healthy vitamin D levels now often depends on alternative sources, including vitamin D3 supplements.
While numerous observational studies have linked low vitamin D levels to poorer heart health, earlier clinical trials using standard supplement doses did not show improvements in cardiovascular risk. This led Intermountain heart researchers to question whether achieving a specific blood level of vitamin D might be more effective than simply giving a uniform supplement dose to all patients.
“Previous studies just gave patients supplementation without regularly checking blood levels of vitamin D to determine what supplementation achieved,” said Dr. May. “With more targeted treatment, when we checked exactly how supplementation was working and made adjustments, we found that patients had their risk of another heart attack cut in half.”
The Intermountain study, called the TARGET-D trial, enrolled patients from April 2017 to May 2023 and included 630 Intermountain Health patients who had a heart attack within a month of their enrollment. Participants were followed until March 2025 for the occurrence of cardiovascular events.
How the Study Worked
Researchers randomized study patients into two groups: those who received no management of vitamin D3 by the study and those who received targeted vitamin D3 treatment.
In the vitamin D treatment group, the goal was to raise their blood levels of vitamin D to more than 40 nanograms per ml (ng/mL). Of the heart attack patients enrolled in the study, 85% had insufficient vitamin D3 levels (<40 ng/mL).
Of those who received targeted treatment, more than 50% required an initial vitamin D3 dose of 5,000 international units (IU), where current supplementation suggestions are usually between 600 to 800 IU.
For patients in the study who received targeted treatment, their vitamin D blood levels were checked once a year to determine if they were above 40 ng/mL. For patients whose vitamin D levels were lower, they were tested every three months with their dosage adjusted, then every year after they achieved 40 ng/mL.
Intermountain researchers then followed patients to see who had follow-up major cardiac events (MACE), including heart attack, heart failure hospitalization, stroke, or death.
Of the 630 patients enrolled in the clinical trial, 107 experienced a major cardiac event.
Researchers found no significant difference in the risk of MACE between the groups. However, they did find that the risk of a follow-up heart attack was reduced by half in those patients who received targeted vitamin D management.
The next step for researchers is to do a larger clinical trial to reaffirm these findings.
A larger study group will allow researchers to adequately evaluate whether targeted vitamin D management reduces the risk of developing or reducing the risk of other cardiovascular disease, said Dr. May.
Meeting: American Heart Association Scientific Sessions 2025
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4 Comments
Dont fall for the scam of thinking you need a supplement.
Go outside and get some sun. Dont fall for the “cancer risk” bullcrap either.
Unless you spend hours outside in the most intense period of sun every single day you have no incresed cancer risk.
They will try to convince you of anything to get you taking more supplements and pills.
Bulls***. You CAN NOT get enough sunlight to produce the vitamin D you need by “going outside and getting some sun.” It is physically impossible. You absolutely need to take vitamin D supplements.
Take your conspiracy theories, fold them 5 ways, and shove them…
You have to watch the intake of D3 carefully. Too much can cause problems. To avoid Covid 19, I began taking 4000IU a day. After a month or so, I started having tingling in my hands and feet. I would stop the D3, and the tingling would go away after a week. D3 enters the body slowly, and it leaves the body slowly. So, you have to be careful. Now I take 1000IU (2) times a week. That seems to do the trick. But that’s my situation. Yours may be different.
Like the paper said, measure your Vit D levels BEFORE starting a supplement regimen. Then start with your supplements and wait 2-3 months. Get tested again and then adjust. I took Vit D/K2 daily, and found my levels were higher than desired, above 100. So, I adjusted to every other day dosing. This brought my levels down to 50-60 which is ideal for overall health. Many doctors who focus on longevity advise to take Vit D to get your levels above a set target, as this article advises. It seems they were right after all.