Vitamin D and Heart Health: Latest Summary of Scientific Evidence

Published on February 5, 2026

Measuring Vitamin D Levels is One of Several Key, Evidence-Based Tests for Improving Cardiovascular Health

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A newly published 2026 review paper by Varzideh et al., Vitamin D in Cardiovascular Medicine: From Molecular Mechanisms to Clinical Translation, ties together decades of research to clarify what vitamin D means for heart and cardiovascular health and why testing vitamin D status is so important.

The takeaway: vitamin D is deeply involved in cardiovascular biology, and low levels consistently identify individuals at higher cardiovascular risk, especially when viewed alongside other inflammatory and metabolic markers.

Vitamin D: Well Beyond Bone Health

Traditionally associated with bone health, vitamin D is now recognized as a hormone that influences many systems relevant to cardiovascular disease. Vitamin D receptors are found in almost all cells and tissues, including heart muscle cells, blood vessels, and immune cells, allowing vitamin D to directly affect vascular tone, inflammation, and cardiac function. Low blood levels of 25-hydroxyvitamin D, the standard marker of vitamin D status, are widespread and overlap strikingly with populations at higher risk for heart disease, including older adults, individuals with obesity, and those with limited sun exposure.

How Vitamin D Is Activated and Why Blood Levels Matter

Vitamin D must undergo multiple activation steps in the liver and kidneys before it can exert biological effects. Because this process is influenced by genetics, kidney function, inflammation, and overall metabolic health, simply taking vitamin D does not guarantee optimal activity at the tissue level. This is why measuring circulating 25-hydroxyvitamin D is so important: it provides a stable snapshot of vitamin D availability in the blood and acts as an integrated marker of lifestyle, metabolic health, and systemic resilience.

Vitamin D deficiency may contribute to hypertension, endothelial dysfunction, atherosclerosis, and heart failure risk.

Supporting Healthy Heart Structure and Function

The review by Varzideh et al. highlights vitamin D’s role in maintaining normal heart and blood vessel function throughout life. Vitamin D signaling helps regulate calcium handling in heart muscle cells, supports normal contraction and relaxation, and contributes to healthy blood vessel structure. Deficiency has been linked to increased arterial stiffness, impaired endothelial function, and less efficient heart muscle performance—all early changes that precede overt cardiovascular disease.

Vitamin D, Inflammation, and hsCRP

One of the strongest links between vitamin D and heart disease lies in inflammation. Vitamin D helps regulate immune responses and dampen pro-inflammatory signaling pathways involved in atherosclerosis. Observational studies consistently show that lower vitamin D levels are associated with higher levels of high-sensitivity C-reactive protein (hsCRP), a well-established marker of cardiovascular inflammation.

Importantly, individuals with both low vitamin D and elevated hsCRP have substantially higher cardiovascular and all-cause mortality risk than those with either factor alone, reinforcing the value of measuring these markers together.

Oxidative Stress, Mitochondria, and Vascular Health

Vitamin D also plays a role in protecting cells from oxidative stress—a major driver of vascular damage and plaque formation. Varzideh et al. describes how vitamin D supports mitochondrial function and antioxidant defenses in both heart and blood vessel cells. When vitamin D levels are low, oxidative stress increases, contributing to endothelial dysfunction and impaired blood flow. This biological pathway helps explain why vitamin D status often tracks with cardiovascular vulnerability.

Blood Pressure and Hormonal Balance

Another key mechanism involves the renin–angiotensin–aldosterone system (RAAS), which regulates blood pressure and fluid balance. Vitamin D acts as a natural brake on this system. Low vitamin D levels are associated with higher renin activity, increased blood pressure, and unfavorable cardiac remodeling. Measuring vitamin D provides insight into this hormonal balance, especially for individuals concerned about hypertension or cardiovascular strain.

Vitamin D as a Cardiovascular Risk Marker

Large population studies consistently associate low vitamin D levels with higher risks of heart attack, stroke, heart failure, and cardiovascular mortality. While large supplementation trials have not shown universal reductions in cardiovascular events, the authors emphasize that vitamin D appears to function more as a risk marker and modifier than as a one-size-fits-all treatment. In other words, low vitamin D often signals broader cardiometabolic stress, inflammation, and reduced physiological reserve; information that is clinically valuable when assessing overall cardiovascular risk.

Well-designed clinical trials, such as the TARGET-D study from Intermountain Health, adds solid evidence to the idea that vitamin D status isn’t just a correlate of heart health but may be a meaningful factor to manage in people with existing cardiovascular disease. In this trial, researchers monitored patients’ blood levels of vitamin D and adjusted vitamin D supplement doses to reach and maintain a target level of ≥ 40 ng/mL. This personalized, dose to target level strategy was associated with about a 50 % lower risk of a second heart attack compared with standard care in people who had already experienced a cardiac event.

What’s especially important for cardiovascular risk assessment is that this benefit emerged when vitamin D levels were actively measured and optimized, reinforcing that testing vitamin D status (rather than simply supplementing without knowing a level) can uncover a modifiable risk factor, one that carries actionable insights alongside markers like the omega-3 index and hsCRP that reflect inflammation and cardiometabolic balance.

Why Vitamin D Should Be Measured Alongside Omega Fatty Acids

The authors’ conclusions align well with a precision-based approach to cardiovascular prevention. Measuring vitamin D alongside other actionable biomarkers, such as the Omega-3 Index and the ratio of Omega-3s to Omega-6s, which reflects anti- and pro-inflammatory fatty acid status, provides a more complete picture of cardiovascular health. Omega fatty acid levels influence inflammation, endothelial function, and plaque stability, while vitamin D reflects immune balance, vascular regulation, and metabolic health. Together, these markers help identify modifiable risk patterns that can be acted upon easily through lifestyle and dietary changes.

Evidence-Based Tests for Improving Cardiovascular Health – Special Savings This Month!

This comprehensive review reinforces an important message: vitamin D is deeply embedded in cardiovascular biology, and low levels consistently identify individuals at higher risk. Measuring vitamin D, especially in combination with hsCRP and the omega fatty acids, offers meaningful insight into inflammation, vascular health, and overall cardiovascular resilience.

As we move through February – Heart Health Month! – this research highlights why testing is essential. Understanding your vitamin D status alongside other key cardiovascular markers can help guide informed decisions about lifestyle, nutrition, and targeted interventions that support long-term health for your heart and cardiovascular system.

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Create Your Custom Home Test Kit

Measure your vitamin D levels at home as part of the D*action project! To know if you are getting enough, make sure you test today!

You can also measure your:

• Vitamin D
• Magnesium PLUS Essential and Toxic Elements
• Omega-3 Fatty Acids
• hsCRP
• HbA1c
• TSH
• Type 1 Diabetes Autoantibodies

Did you know that each of the above can be measured at home using a simple blood spot test? As part of our ongoing research project, you can order your home blood spot test kit to get your levels, followed by education and steps to take to help you reach your optimal target levels. Start by enrolling and ordering your kit to measure each of the above important markers, and make sure you are getting enough of each to support better mood and wellbeing!

Create your custom home test kit today. Take steps to improve the status of each of these measurements to benefit your overall health. With measurement you can then determine how much is needed and steps to achieve your goals.  You can also track your own intakes, symptoms and results to see what works best for YOU.