🟡 Preliminary Evidence
A randomized trial presented at the American Heart Association Scientific Sessions 2025 found that adjusting vitamin D supplementation to reach target blood levels reduced recurrent heart attacks by 52% in patients with prior acute coronary syndrome, though the findings remain preliminary pending full peer review.
Key takeaways
- Tailored vitamin D dosing (adjusted every 3 months to maintain 40–80 ng/mL blood levels) reduced recurrent myocardial infarction by 52% compared to standard care over 4.2 years of follow-up
- At baseline, 85% of the 630 study participants had vitamin D insufficiency (<40 ng/mL), and approximately 52% of the treatment group required doses exceeding 5,000 IU/day to reach target levels
- The benefit was limited to heart attack recurrence; no significant differences were observed in mortality, stroke, or heart-failure hospitalization between groups
- This is a preliminary abstract from a scientific conference and has not yet undergone peer review; results require confirmation in published literature
Study at a Glance
| Source | American Heart Association Scientific Sessions |
| Study type | Randomized controlled trial (abstract format) |
| Sample size | N = 630 |
| Population | Adults (~63 years old) with acute coronary syndrome |
| Duration | 4.2 years average follow-up |
| Status | Preliminary; full peer-reviewed publication pending |
Baseline Vitamin D Status and Dosing Requirements
Proportion of study participants with insufficiency and high-dose requirements, TARGET-D trial (2025)
Source: American Heart Association Scientific Sessions 2025 | Georgian Medical Journal News
A New Approach to Vitamin D Dosing in Heart Disease
Prior vitamin D supplementation trials in cardiovascular disease have typically administered fixed doses to all participants, regardless of baseline blood levels or individual variation in absorption and metabolism. According to the Clinical Updates literature, this one-size-fits-all approach may explain inconsistent findings across previous randomized trials. The TARGET-D trial adopted a fundamentally different strategy: adjusting vitamin D intake every 3 months to maintain each participant’s serum 25-hydroxyvitamin D (25(OH)D) concentration within a physiologically targeted range of 40–80 ng/mL.
The rationale stems from observational research linking vitamin D insufficiency to increased cardiovascular event risk in patients with established heart disease. However, observational associations do not establish causation, and prior fixed-dose RCTs have yielded mixed results—a discrepancy the researchers hypothesized might reflect inadequate dosing in some participants. The new trial tested whether individualized titration could improve outcomes.
Study Design and Key Findings
The trial enrolled 630 adults (mean age ~63 years) with a recent acute coronary syndrome (heart attack or unstable angina). Participants were randomly assigned to either standard cardiac care alone or standard care plus tailored vitamin D supplementation. At baseline, 85% of the cohort had 25(OH)D levels below 40 ng/mL, indicating widespread insufficiency. Over 4.2 years of follow-up, the tailored-dosing group experienced a 52% lower rate of recurrent myocardial infarction compared to the standard-care group.
Notably, approximately 52% of participants in the treatment arm required daily doses exceeding 5,000 IU to achieve and maintain the target 25(OH)D range. Doses were reduced if levels exceeded 80 ng/mL, ensuring safety. Both groups received guideline-directed medical therapy for coronary disease (antiplatelet agents, statins, beta-blockers, and angiotensin-converting enzyme inhibitors or angiotensin receptor blockers as appropriate).
Recurrent heart attacks occurred 52% less often in the tailored-dosing group versus standard care, suggesting that achieving specific vitamin D blood-level targets may reduce acute cardiovascular events in patients with prior coronary syndrome.
— American Heart Association Scientific Sessions (2025, abstract format)
Important Caveats and Limitations
This study was presented as an abstract at a scientific conference and has not yet undergone peer review or full publication in a peer-reviewed medical journal. The findings are therefore preliminary and require confirmation. The study cohort was predominantly white (approximately 90%), limiting generalizability to other racial and ethnic populations. Additionally, only adults with established coronary artery disease were enrolled, so the results do not address whether tailored vitamin D supplementation would benefit primary prevention in asymptomatic individuals.
Furthermore, the benefit was confined to recurrent myocardial infarction; no statistically significant differences were observed between groups for mortality, stroke, or heart-failure hospitalization. This selective benefit raises questions about biological plausibility and whether the finding represents a true treatment effect or could reflect chance, particularly given that this is a preliminary abstract. Long-term safety data on sustained vitamin D supplementation (particularly at doses exceeding 5,000 IU/day) warrant continued surveillance, especially regarding hypercalcemia and kidney stone risk in susceptible populations.
Clinical and Research Implications
If confirmed in a fully published, peer-reviewed report, this trial would suggest that one reason prior vitamin D trials produced inconsistent results is that many participants never achieved physiologically meaningful blood levels. Titrated dosing represents a mechanistically sound refinement to trial design that may resolve conflicting evidence. For patients with coronary artery disease and vitamin D insufficiency, these preliminary findings suggest potential benefit, but individual clinical decisions should await full publication and clinician assessment of cardiovascular risk factors.
The trial also highlights the importance of measuring actual biomarker levels rather than assuming fixed doses produce uniform effects across a population. Future cardiovascular prevention trials may increasingly incorporate personalized dosing strategies and biochemical endpoints rather than relying on fixed protocols. Nevertheless, until these results are published in full and independently replicated, they should be interpreted as hypothesis-generating rather than definitive clinical guidance.
What this means
Frequently asked questions
Is vitamin D supplementation now recommended for all heart disease patients?
No. This is a single preliminary abstract that has not undergone peer review. Current cardiac prevention guidelines do not universally recommend vitamin D supplementation based on existing evidence. Any supplementation decisions should be made with your cardiologist after full publication and further confirmation of these findings.
What is the target vitamin D blood level, and is it safe?
The trial targeted a 25(OH)D range of 40–80 ng/mL (100–200 nmol/L). This range is generally considered sufficient for bone and metabolic health. However, long-term safety of sustained doses exceeding 5,000 IU/day—required in about half the trial’s treatment group—requires ongoing evaluation, particularly for risk of hypercalcemia and kidney stones.
Why did the benefit only appear for heart attack recurrence and not for stroke or death?
This selective benefit is intriguing but raises important questions about biological mechanism and whether the finding might reflect chance variation in a preliminary analysis. The reasons for the lack of benefit on other outcomes are unclear and highlight the need for full peer-reviewed publication and mechanistic study before drawing clinical conclusions.
Full publication of the TARGET-D trial in a peer-reviewed journal will be essential to confirm these findings, clarify baseline characteristics and outcome definitions, and establish whether personalized vitamin D dosing should be incorporated into routine cardiovascular prevention. Clinicians and patients should await that publication before making significant changes to current supplementation practices.
Source: American Heart Association Scientific Sessions 2025 (abstract format; full peer-reviewed publication pending)
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