Researchers combined results from 9 large studies involving over 114,000 people to see if taking vitamin D supplements could prevent heart disease. They found that vitamin D supplements did not reduce the risk of heart attacks, strokes, or other major heart problems compared to a placebo (fake pill). While vitamin D is important for bone health and other body functions, this analysis suggests it may not be the heart-protection tool many people hoped it would be. The findings challenge the popular belief that vitamin D supplements can prevent cardiovascular disease.
The Quick Take
- What they studied: Whether taking vitamin D pills could prevent heart disease, heart attacks, and related deaths in adults
- Who participated: Over 114,000 adults across 9 different research studies. Participants were randomly assigned to either take vitamin D supplements or a placebo pill, and researchers tracked their heart health over time
- Key finding: Vitamin D supplements did not reduce heart disease risk compared to placebo. The numbers were almost identical between the two groups—vitamin D showed no meaningful protection against heart attacks, strokes, or heart-related deaths
- What it means for you: If you’re taking vitamin D specifically to prevent heart disease, this research suggests it probably won’t help with that goal. However, vitamin D remains important for bone health and other body functions, so talk to your doctor about whether you need it for other reasons
The Research Details
This is a meta-analysis, which means researchers searched through thousands of published studies and selected 9 high-quality randomized controlled trials to combine and analyze together. Randomized controlled trials are considered the gold standard in medical research because participants are randomly assigned to either receive vitamin D or a placebo, which helps eliminate bias.
The researchers carefully searched three major medical databases (PubMed, Cochrane Library, and ClinicalTrial.gov) using specific keywords related to vitamin D and heart disease. Two independent reviewers checked each study to make sure it met strict quality standards. They extracted data from each study and combined the results using statistical methods to see if there was an overall pattern.
The studies they included involved 114,379 total participants who were followed for varying lengths of time. By combining all these studies, the researchers had enough data to detect even small protective effects of vitamin D if they existed.
This research approach is important because individual studies sometimes show conflicting results—some suggest vitamin D helps, while others show no benefit. By combining multiple large, well-designed studies, researchers can see the bigger picture and determine what the overall evidence really shows. This meta-analysis approach gives us much more reliable answers than looking at any single study alone
This study is a systematic review and meta-analysis, which is one of the highest levels of scientific evidence. The researchers used rigorous methods: they searched multiple databases, had two independent reviewers check studies for quality, assessed bias using established tools, and registered their analysis plan in advance (PROSPERO) to prevent cherry-picking results. The studies included were randomized controlled trials, which are the gold standard for testing whether a treatment works
What the Results Show
The main finding was clear: vitamin D supplements did not reduce the overall risk of cardiovascular disease events compared to placebo. When the researchers combined all the data, the risk ratio was 0.95, which means vitamin D showed virtually no difference from the placebo pill.
When looking at specific heart problems, the pattern held. Vitamin D did not reduce the risk of heart attacks (myocardial infarction), with a risk ratio of 0.96—essentially the same as placebo. The supplements also did not reduce deaths from heart disease overall or deaths specifically from heart attacks.
The researchers were careful to note that their findings were consistent across the different studies they analyzed. This consistency strengthens their conclusion that vitamin D is not an effective preventive treatment for major heart disease events in the general adult population.
While vitamin D did not prevent heart disease, the analysis also looked at heart-related deaths specifically. Interestingly, vitamin D showed no protective effect here either, with results actually trending slightly higher (though not statistically significant). This means the data does not support using vitamin D to prevent heart disease deaths. The analysis examined multiple types of cardiovascular events and found no benefit across any of them
This finding may surprise people because vitamin D has been heavily promoted for heart health in recent years. Some earlier studies and observational research suggested vitamin D might help prevent heart disease, which led many people to take supplements. However, this comprehensive analysis of the highest-quality studies (randomized controlled trials) shows that when people are actually tested with vitamin D versus placebo, the supplement doesn’t deliver the heart protection that was hoped for. This demonstrates why it’s important to look at rigorous experimental evidence rather than relying on observational studies alone
The studies included were conducted over different time periods and used varying doses of vitamin D, which could affect results. Some studies followed people for longer periods than others, and participants had different baseline health statuses. The analysis combined studies that measured outcomes slightly differently, though researchers tried to account for this. Additionally, most participants in these studies were relatively healthy at the start, so results may not apply to people with existing heart disease or severe vitamin D deficiency. The studies were also mostly conducted in developed countries, so findings may not apply globally
The Bottom Line
Based on this evidence, vitamin D supplements are not recommended specifically for preventing heart disease in healthy adults (moderate confidence level). However, vitamin D remains important for bone health and immune function. If you’re considering vitamin D supplements, discuss with your doctor whether you need them for other health reasons, such as bone health or if you have low vitamin D levels. Don’t stop taking vitamin D if your doctor recommended it for other purposes
This research matters most for people taking vitamin D specifically hoping to prevent heart disease. It’s relevant for healthy adults considering starting vitamin D supplements for heart protection. People with existing heart disease, those with vitamin D deficiency, and those taking vitamin D for bone health should still consult their doctors, as this study doesn’t address those situations. Healthcare providers should be aware of this evidence when counseling patients about heart disease prevention
The studies analyzed followed participants for varying lengths of time, ranging from months to several years. If vitamin D were going to prevent heart disease, benefits should have appeared within these timeframes. You shouldn’t expect to see heart disease prevention benefits from vitamin D supplements at any point, based on this evidence
Want to Apply This Research?
- Track your vitamin D supplementation (yes/no, dosage) alongside other heart health metrics like blood pressure, exercise minutes, and diet quality. This helps you see the complete picture of your cardiovascular health efforts rather than relying on any single supplement
- Instead of relying on vitamin D for heart protection, focus on proven heart-healthy behaviors: regular exercise (150 minutes weekly), eating more fruits and vegetables, managing stress, maintaining a healthy weight, and not smoking. Use the app to track these evidence-based habits
- Monitor your overall cardiovascular health through multiple factors: blood pressure readings, cholesterol levels (if available), exercise consistency, diet quality, and weight. Track vitamin D levels if your doctor recommends it for bone health, but don’t expect it to show up as improved heart disease markers
This analysis of clinical trials shows that vitamin D supplements do not prevent cardiovascular disease in healthy adults. However, this research does not apply to people with vitamin D deficiency, existing heart disease, or those taking vitamin D for bone health. Vitamin D remains important for other body functions. Always consult with your healthcare provider before starting, stopping, or changing any supplement regimen, especially if you have heart disease risk factors or existing cardiovascular conditions. This information is for educational purposes and should not replace professional medical advice.