Can vitamin c raise blood pressure
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Can Vitamin C Raise Blood Pressure?
Vitamin C and Blood Pressure: An Overview
Vitamin C, a well-known antioxidant, has been extensively studied for its potential effects on blood pressure (BP). Observational studies and clinical trials have provided mixed results, with some suggesting a beneficial effect on BP, while others indicate no significant impact or even a potential increase in certain conditions.
Evidence from Observational Studies
Several observational studies have consistently shown an inverse relationship between vitamin C levels and blood pressure. Higher plasma vitamin C levels are generally associated with lower systolic and diastolic blood pressure 236. For instance, a systematic review of epidemiological studies found that 10 out of 14 cross-sectional studies reported an inverse association between plasma vitamin C and BP, and three out of four studies reported an inverse association with vitamin C intake . Another review highlighted that hypertensive individuals tend to have lower serum vitamin C levels compared to normotensive individuals, reinforcing the inverse relationship between vitamin C and BP .
Clinical Trials and Meta-Analyses
Short-Term Effects
Meta-analyses of randomized controlled trials (RCTs) have shown that short-term vitamin C supplementation can lead to modest reductions in BP. One meta-analysis of 29 trials found that vitamin C supplementation reduced systolic BP by an average of 3.84 mm Hg and diastolic BP by 1.48 mm Hg . Another systematic review confirmed these findings, showing a reduction in systolic BP by 3.0 mm Hg and a more pronounced effect in hypertensive and diabetic patients .
Long-Term Effects
However, the long-term effects of vitamin C supplementation on BP are less clear. A double-blinded RCT involving Japanese subjects over five years found no significant reduction in BP with vitamin C supplementation. In fact, systolic BP increased in both the high-dose (500 mg/day) and low-dose (50 mg/day) groups . This suggests that while short-term supplementation may have a beneficial effect, long-term supplementation does not sustain these benefits and may even lead to an increase in BP.
Combination with Other Supplements
Interestingly, the combination of vitamin C with other antioxidants, such as grape-seed polyphenols, has shown a different outcome. A study found that while vitamin C alone reduced systolic BP, the combination with polyphenols actually increased both systolic and diastolic BP significantly . This indicates that the interaction between different supplements can alter the effects on BP, and caution is advised when combining vitamin C with other antioxidants.
Conclusion
In summary, while short-term vitamin C supplementation appears to lower blood pressure modestly, the long-term effects are less clear and may not be beneficial. Additionally, combining vitamin C with other supplements like polyphenols can potentially increase blood pressure. Therefore, individuals, especially those with hypertension, should consult healthcare providers before starting any new supplement regimen. Further long-term studies are needed to fully understand the impact of vitamin C on blood pressure and cardiovascular health.
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