Is taking vitamin C good for your heart? The surprising truth about supplements and diet

October 21, 2025 •

5 min read

According to the World Health Organization, cardiovascular disease is the leading cause of death globally, accounting for nearly 18 million deaths each year. This staggering statistic prompts a closer look at preventative measures, including the question: is taking vitamin C good for your heart?

Quick Summary

The impact of vitamin C on heart health depends on the source, with evidence strongly favoring a diet rich in fruits and vegetables over supplements for preventative care. Supplemental vitamin C shows inconsistent results in clinical trials.

Key Points

Dietary intake is preferred: Consistent evidence shows that consuming vitamin C from a diet rich in fruits and vegetables is correlated with lower cardiovascular disease (CVD) risk.
Supplements are not a proven replacement: Large-scale clinical trials have found inconsistent or no significant benefits of vitamin C supplements for preventing major cardiovascular events.
Mechanisms are promising but context is key: Vitamin C acts as a powerful antioxidant, supports healthy blood vessel function, and helps manage blood pressure, but the full benefits are likely tied to the complete nutrient profile of whole foods.
High-doses have risks: Taking over 2,000 mg of vitamin C in supplements daily can lead to unpleasant side effects like digestive issues and an increased risk of kidney stones.
Focus on whole foods: The most effective strategy for heart health is to consistently consume vitamin C from natural sources like oranges, bell peppers, strawberries, and broccoli.
Consider individual health factors: Benefits of supplementation may be more pronounced in individuals with low baseline vitamin C levels or specific health conditions, such as those with existing hypertension.

The Dual Nature of Vitamin C: Diet vs. Supplements

For many years, the antioxidant properties of vitamin C have led to the widespread belief that high-dose supplements are a shortcut to better health, including cardiovascular wellness. However, the relationship between vitamin C and heart health is more complex and nuanced, with research indicating a clear distinction between the effects of dietary intake and supplementation. Most health organizations emphasize that obtaining nutrients from a balanced diet is superior to relying on supplements.

The Mechanisms of Vitamin C for Heart Health

Vitamin C, also known as ascorbic acid, contributes to cardiovascular health through several key biological functions.

Antioxidant and Anti-inflammatory Effects

Oxidative stress and chronic inflammation are fundamental drivers of atherosclerosis, the buildup of plaque in arteries that can lead to heart attacks and strokes. As a powerful antioxidant, vitamin C helps neutralize free radicals, thereby protecting blood vessel walls from damage. It also plays an anti-inflammatory role, modulating cytokine production and potentially inhibiting key inflammatory pathways.

Supporting Endothelial Function

Endothelial dysfunction, or damage to the inner lining of blood vessels, is an early sign of cardiovascular disease. Vitamin C contributes to maintaining healthy endothelial function by:

Promoting the production of nitric oxide, a molecule that signals blood vessels to relax, improving blood flow and reducing blood pressure.
Stabilizing tetrahydrobiopterin (BH4), a crucial cofactor for endothelial nitric oxide synthase (eNOS).
Inhibiting LDL cholesterol oxidation, which is a key step in plaque formation.

Maintaining Blood Vessel Integrity

Vitamin C is an essential cofactor for the synthesis of collagen, the main structural protein in blood vessels and other connective tissues. Strong and flexible blood vessels are vital for proper circulation and can reduce the risk of arterial disease. A deficiency can lead to weakened blood vessels, a hallmark of scurvy, which highlights its importance for cardiovascular integrity.

Contrasting Evidence: Diet vs. Supplemental Vitamin C

While the theoretical mechanisms for vitamin C's cardiovascular benefits are strong, clinical outcomes differ significantly depending on the source. Here is a comparison of findings from different types of studies:


Feature	Dietary Vitamin C (from food)	Supplemental Vitamin C (pills)
Associated with Lower CVD Risk?	Yes, consistently correlated in observational studies due to association with healthier overall diet and lifestyle.	Inconsistent results. Some observational studies show a link, but large-scale randomized trials often find no significant effect.
Effect on Blood Pressure	Associated with an inverse relationship, likely due to a combination of vitamin C and other compounds in fruits and vegetables.	Some short-term studies suggest a modest reduction in blood pressure, particularly in those with existing hypertension.
Effect on Cholesterol	No consistent effect on blood lipids in most studies when isolated from other dietary factors.	A meta-analysis found a modest reduction in LDL and triglycerides with at least 500mg daily, but other trials show no significant change.
Overall CVD Mortality	Higher intake from food, especially fruits and vegetables, is associated with lower cardiovascular mortality.	Large trials show little or no effect on major cardiovascular events or overall mortality from CVD in well-nourished populations.
Risks of High Intake	Extremely low risk of adverse effects from food sources, as the body tightly regulates absorption.	Higher doses (over 2,000 mg/day) can lead to digestive issues, and in some individuals, increase the risk of kidney stones.

The Mixed Results of Clinical Trials

Major randomized controlled trials (RCTs) have produced inconsistent and, at times, disappointing results regarding vitamin C supplementation and heart health. For example, the Physicians Health Study II found no cardiovascular benefit from long-term daily supplementation in healthy men. The Women's Angiographic Vitamin and Estrogen (WAVE) trial showed a greater worsening of coronary progression in a group taking high-dose antioxidants, including vitamin C.

Several factors may explain the discrepancy between observational data and clinical trial results:

Dietary Synergy: The cardiovascular benefits observed in dietary studies likely stem from the synergistic effects of vitamin C combined with other nutrients, fiber, and phytochemicals present in whole foods.
Baseline Status: Most trial participants are already well-nourished. Supplementation may have a more pronounced effect in individuals with low baseline vitamin C levels, who are at higher risk for CVD.
Methodological Limitations: Some trials have been criticized for insufficient follow-up time, use of supplemental rather than dietary vitamin C, and reliance on self-reported dietary intake.

Potential Risks of Over-Supplementation

While generally safe, exceeding the Tolerable Upper Intake Level (UL) of 2,000 mg/day from supplements can lead to side effects.

Digestive Issues: The most common side effects include nausea, diarrhea, and stomach cramps.
Kidney Stones: The body excretes excess vitamin C as oxalate. High doses can increase urinary oxalate, raising the risk of kidney stone formation, particularly for those with a history of the condition.
Iron Overload: For individuals with hemochromatosis, a condition causing excessive iron accumulation, high vitamin C intake can exacerbate iron overload, leading to organ damage.

How to Optimize Your Vitamin C for Heart Health

Rather than relying on supplements, the most reliable way to leverage vitamin C's heart-healthy potential is through a balanced, whole-foods diet. A consistent intake is key, as the body does not store large reserves.

Here are some excellent food sources of vitamin C, many of which also provide other heart-healthy benefits like fiber and antioxidants:

Citrus fruits (oranges, grapefruit)
Strawberries and kiwi fruit
Bell peppers (especially red)
Cruciferous vegetables (broccoli, Brussels sprouts, kale)
Tomatoes and potatoes

These foods provide not just vitamin C but a complete package of nutrients that contribute to a healthier lifestyle, mirroring the habits associated with reduced cardiovascular risk.

Conclusion: A Prudent Path Forward

While preclinical evidence and observational studies suggest vitamin C has cardioprotective properties, the definitive answer to "is taking vitamin C good for your heart?" depends on context. The evidence strongly supports a heart-healthy diet rich in whole foods containing vitamin C, which provides synergistic benefits beyond isolated nutrient supplementation. High-dose supplements, on the other hand, have yielded inconsistent results in large-scale clinical trials and carry potential risks. For most healthy individuals, meeting the Recommended Dietary Allowance (RDA) through diet is sufficient and superior for cardiovascular health. As with any supplement, it is best to consult a healthcare provider before beginning a new regimen. For further information on recommended intake levels for health professionals, consult the National Institutes of Health Fact Sheet.

Frequently Asked Questions

Overall, large clinical trials have not found consistent evidence that taking vitamin C supplements significantly protects against major cardiovascular events like heart attack and stroke, especially in well-nourished populations.

Vitamin C acts as a powerful antioxidant, helping to reduce oxidative stress and inflammation in the body. It also supports endothelial function by promoting nitric oxide production, which helps relax blood vessels and lower blood pressure.

For heart health, it is generally better to get vitamin C from food. A diet rich in vitamin C-containing fruits and vegetables provides a synergistic mix of nutrients and fiber that is consistently linked to better cardiovascular outcomes, unlike supplements alone.

Yes, taking excessively high doses, typically above 2,000 mg per day, can cause digestive upset like diarrhea and cramps. In some cases, it can also increase the risk of kidney stones or, for people with hemochromatosis, iron overload.

Some studies suggest that vitamin C supplementation can lead to a modest reduction in blood pressure, particularly in individuals with high blood pressure. However, it should not be relied upon as a sole treatment.

One observational study found a correlation between higher supplemental vitamin C intake and increased CVD mortality in postmenopausal women with diabetes, suggesting potential risks in specific populations.

Excellent food sources of vitamin C include bell peppers, citrus fruits, strawberries, kiwi, broccoli, and kale. Eating a varied diet rich in these foods is the most recommended approach for heart health.