"Previous studies just gave patients supplementation without regularly checking blood levels of vitamin D to determine what supplementation achieved," said principal investigator Heidi May, PhD, cardiovascular epidemiologist at Intermountain Health, in a press release.
"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,” she added.
Observational research indicates that low vitamin D levels are linked to poor cardiovascular outcomes. Clinical trials, however, suggest that standard supplementation doses do not reduce heart disease risk. These findings led the researchers behind the current study to wonder whether customized vitamin D doses that ensure specific, healthy vitamin D levels may work better than giving everyone the same dose.
To test this out, they conducted the TARGET-D trial between 2017 and 2023, which included 630 patients who had a heart attack within a month of enrollment. They were split into two groups: one receiving targeted vitamin D3 treatment, which aimed to raise vitamin D levels to above 40 nanograms per milliliter (ng/mL), and one receiving no vitamin D management. The patients were followed until 2025 for cardiovascular outcomes.
At the start of the study, 85% of patients had vitamin D3 levels below 40 ng/mL. Over half of the patients on the targeted therapy required a starting dose of 5,000 international units (IU) of vitamin D3, compared to the typical recommendations of 600-800 IU.
Patients with lower vitamin D levels were tested every three months and had their dosage adjusted until they reached the 40 ng/mL target. Those whose vitamin D blood levels were 40 ng/mL or above were checked once per year.
The researchers found no difference in risk of major cardiac events- heart attacks, strokes, heart failure, hospitalizations, and deaths- between the two groups. They found, however, that risk of having a second heart attack fell by 50% among those receiving targeted vitamin D treatment. The researchers reported no adverse outcomes when giving patients higher doses of vitamin D3.
"We're excited with these results but know we have further work to do to validate these findings,” said May.
The researchers now hope to conduct a larger clinical trial.
Sources: Science Daily
