Does vitamin c raise blood pressure
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The Impact of Vitamin C on Blood Pressure: A Comprehensive Review
Introduction to Vitamin C and Blood Pressure
Vitamin C, also known as ascorbic acid, is a vital nutrient known for its antioxidant properties. Its potential role in managing blood pressure (BP) has been a subject of extensive research. This article synthesizes findings from multiple studies to determine whether vitamin C supplementation affects blood pressure levels.
Vitamin C and Blood Pressure: Observational Studies
Observational studies have consistently shown an inverse relationship between vitamin C levels and blood pressure. Higher vitamin C intake and serum levels are associated with lower systolic blood pressure (SBP) and diastolic blood pressure (DBP)2 3 7. For instance, a systematic review of observational studies found that hypertensive individuals had significantly lower serum vitamin C levels compared to normotensive individuals, and higher vitamin C levels were inversely correlated with both SBP and DBP2.
Clinical Trials on Vitamin C Supplementation
Short-Term Effects
Several randomized controlled trials (RCTs) have investigated the short-term effects of vitamin C supplementation on blood pressure. A meta-analysis of 29 trials revealed that vitamin C supplementation led to modest reductions in both SBP and DBP. Specifically, the pooled changes were -3.84 mm Hg for SBP and -1.48 mm Hg for DBP1. Another review found that vitamin C supplementation reduced SBP by an average of 3.0 mm Hg, with more pronounced effects in hypertensive and diabetic patients5.
Long-Term Effects
The long-term effects of vitamin C supplementation on blood pressure are less clear. A study involving Japanese subjects over five years found no significant reduction in blood pressure with daily vitamin C supplementation, regardless of the dose4. This suggests that while short-term supplementation may have some benefits, these effects may not be sustained over the long term.
Combined Effects with Other Antioxidants
Interestingly, the combination of vitamin C with other antioxidants, such as grape-seed polyphenols, has shown mixed results. One study found that while vitamin C alone slightly reduced SBP, the combination with polyphenols actually increased both SBP and DBP6. This indicates that the interaction between different antioxidants can influence their effects on blood pressure.
Mechanisms and Potential Confounders
The exact mechanisms by which vitamin C may influence blood pressure are not fully understood. It is hypothesized that its antioxidant properties help reduce oxidative stress, which in turn may lower blood pressure. However, many studies did not adequately control for other dietary factors, making it difficult to isolate the effects of vitamin C alone3 7.
Conclusion
In summary, while short-term vitamin C supplementation appears to modestly reduce blood pressure, the long-term benefits are less certain. Observational studies support an inverse relationship between vitamin C levels and blood pressure, but more rigorous, long-term clinical trials are needed to confirm these findings. Additionally, the combination of vitamin C with other antioxidants may have complex effects that warrant further investigation. For now, vitamin C should not be considered a replacement for conventional antihypertensive treatments but may serve as a supplementary measure in managing blood pressure.
Sources and full results
Most relevant research papers on this topic
Effects of vitamin C supplementation on blood pressure: a meta-analysis of randomized controlled trials.
Vitamin C supplementation reduced systolic and diastolic blood pressure in short-term trials, but long-term trials are needed to confirm these effects and confirm their long-term benefits.
Meta-Analysis
Very Rigorous Journal
Highly CitedAssociation between Serum Vitamin C and the Blood Pressure: A Systematic Review and Meta-Analysis of Observational Studies
People with hypertension have relatively low serum vitamin C levels, and vitamin C is inversely associated with both systolic and diastolic blood pressure.
Meta-Analysis
Rigorous JournalVitamin C and blood pressure–an overview
Higher vitamin C intake or status is associated with lower blood pressure, but further studies are needed to confirm this association and its potential impact on cardiovascular disease.
Systematic ReviewHighly CitedLack of Long-Term Effect of Vitamin C Supplementation on Blood Pressure
Long-term moderate doses (500 mg/day) of vitamin C supplementation did not reduce blood pressure in a high-risk population for stomach cancer and stroke.
RCT
Large Human TrialHighly CitedVitamin C supplementation showed greater effects on systolic blood pressure in hypertensive and diabetic patients: an updated systematic review and meta-analysis of randomised clinical trials
Vitamin C supplementation can reduce systolic blood pressure by 3.0 mmHg, with greater effects in hypertensive and diabetic patients.
Meta-AnalysisThe combination of vitamin C and grape-seed polyphenols increases blood pressure: a randomized, double-blind, placebo-controlled trial
The combination of vitamin C and grape-seed polyphenols may increase blood pressure in hypertensive individuals, suggesting caution for those taking these supplements.
RCTHighly CitedVitamin C status and blood pressure
A high intake of vitamin C from food protects against raised blood pressure and strokes, even after accounting for age, sex, and BMI.
Observational StudyHighly CitedEffects of vitamin C supplementation on essential hypertension
Vitamin C supplementation significantly reduces blood pressure in patients with essential hypertension.
Meta-AnalysisVery Rigorous JournalWhat is the evidence that vitamin C supplements lower blood pressure?
Vitamin C supplements show a minor blood pressure-lowering effect, but their clinical significance is insufficient to replace or supplement antihypertensive medications.
Systematic ReviewVery Rigorous JournalVitamin C and cardiovascular risk factors.
Ascorbic acid supplementation may lower blood pressure and cholesterol levels in healthy individuals, but its effects on heart disease risk factors remain unclear.
RCTHighly Cited