Grape Seed Extract + Vitamin C Increases Blood Pressure

Written by on October 1, 2005 in grape seed extract with 8 Comments

A word of warning for anyone who is considering taking Vitamin C and Grape Seed Extract together. Be sure to seek the advice of your doctor first.

The combination of vitamin C and grape-seed polyphenols increases blood pressure: a randomized, double-blind, placebo-controlled trial, Journal of Hypertension 2005 Feb;23(2):427-34.

Background: There is growing evidence that oxidative stress contributes to the pathogenesis of hypertension and endothelial dysfunction. Thus, dietary antioxidants may beneficially influence blood pressure (BP) and endothelial function by reducing oxidative stress.

Objective: To determine if vitamin C and polyphenols, alone or in combination, can lower BP, improve endothelial function and reduce oxidative stress in hypertensive individuals.

Results: A significant interaction between grape-seed and vitamin C treatments for effects on BP was observed. Vitamin C alone reduced systolic BP versus placebo (-1.8 +/- 0.8 mmHg, P = 0.03), while polyphenols did not (-1.3 +/- 0.8 mmHg, P = 0.12). However, treatment with the combination of vitamin C and polyphenols increased systolic BP (4.8 +/- 0.9 mmHg versus placebo; 6.6 +/- 0.8 mmHg versus vitamin C; 6.1 +/- 0.9 mmHg versus polyphenols mmHg, each P < 0.0001) and diastolic BP (2.7 +/- 0.6 mmHg, P < 0.0001 versus placebo; 1.5 +/- 0.6 mmHg, P = 0.016 versus vitamin C; 3.2 +/- 0.7 mmHg, P < 0.0001 versus polyphenols). Endothelium-dependent and -independent vasodilation, and markers of oxidative damage were not significantly altered.

Conclusion: Although the mechanism remains to be elucidated, these results suggest caution for hypertensive subjects taking supplements containing combinations of vitamin C and polyphenols.

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About the Author: David Pascoe started the Rosacea Support Group in October 1998. .

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8 Reader Comments

  1. Mike Spinelli says:

    You start with Grape Seed and switch to Polyphenols.

    Can I assume that Polyphenols are the same?

    Other tests showed that Grape Seed, 200 MG daily, lowered blood pressure. So you are saying that the combination of the two, C and Grape Seed raises the Systolic?

  2. Yes, that is what this research found.

  3. Vikki says:

    As Vitamin C and grapeseed extract taken together raise BP, is it ok to take a vitamin C supplement in the morning, and the grapeseed later in the day? Will this still raise BP?

  4. Hi Vikki, I don’t know personally if there is a safe time where you can mix the two. Perhaps the best advice on this might come from your doctor.


  5. Dan says:

    If you take grapeseed extract, what about the vitamin c in your diet.

  6. nick says:

    I was having a lot of trouble with cold feet, and I was thinking that I had a circulation problem I tryed grape seed extract and it really helped what also helped is apple cider vinegar. I also have two stents in my heart and take blood pressure meds I’m hoping the grape seed extract will help. After reading this article I’m going to avoid vitamin c anyways/

  7. tita bal says:

    i’m not herpertensive my bp goes like 90/70 you think its safe for me to take vitc and grape seed simultaneously ? in fact i need advice if i can take it also together with fish oil(omega3) and primerose.

    • Fiona says:

      No! Unfortunately, as there is no warning on the packet I took anthogenol whilst taking vitamin c and my somewhat normal or slightly raised bp soared to 190/120 requiring hospitalization the same day with a suspected stroke and was admitted. I stopped taking all antioxidants that day as I suspected an interaction problem. It’s now 4 months later and my blood pressure hasn’t reduced and further organ damage has occurred however now I know what caused it I’m confident to use the anthogenol without any other antioxidant to help reduce the damage the 2 products caused as past experience using this product I had terrific results. This product should have a warning on the box as many people use vitamin c as a regular treatment. The chemist I purchased it from Wasnt aware of this toxic result.
      Good luck!

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