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Recommendations Summary

HTN: Vitamins 2008

Click here to see the explanation of recommendation ratings (Strong, Fair, Weak, Consensus, Insufficient Evidence) and labels (Imperative or Conditional). To see more detail on the evidence from which the following recommendations were drawn, use the hyperlinks in the Supporting Evidence Section below.


  • Recommendation(s)

    Vitamin C

    Advise that the consumption of vitamin C may or may not be beneficial for the reduction of blood pressure, since the effect of increased vitamin C intake on blood pressure is unclear.

    Rating: Weak
    Imperative

    Vitamin E

    Advise that the consumption of vitamin E may or may not be beneficial for the reduction of blood pressure, since the effect of increased vitamin E intake on blood pressure is unclear.

    Rating: Weak
    Imperative

    • Risks/Harms of Implementing This Recommendation

      Excessive consumption of vitamin C may result in gastrointestinal disturbances, kidney stones, and excess iron absorption.

      There is no evidence of adverse effects from consumption of vitamin E naturally occurring in foods.  However, adverse effects from supplements containing vitamin E may include hemorrhagic toxicity.

    • Conditions of Application

      Individuals who smoke require an additional 35 mg/day of Vitamin C over that needed by nonsmokers.  Nonsmokers regularly exposed to tobacco smoke are encouraged to ensure that they meet the RDA for vitamin C.

      Patients on anticoagulant therapy should be monitored when taking vitamin E supplements.

    • Potential Costs Associated with Application

      None.

    • Recommendation Narrative

      • Four studies using supplemental doses of at least 500mg of vitamin C per day (over eight times the adult RDA) reported a decrease in systolic blood pressure (SBP) of 1 to 10mm Hg (Fotherby et al, 2000; Duffy et al, 2002; Mullan et al, 2002; Schutte et al, 2004).

      • For diastolic blood pressure (DBP), two studies reported a 4 mmHg decrease following vitamin C supplementation of 500mg or 1, 500mg per day for approximately one month (Block et al, 2000; Mullan et al, 2002). 

      • In one study, high fruit and vegetable intake (over 600g per day) was associated with lower SBP (-3.0mm Hg) in women (not shown in men), however, a similar relationship was not observed between dietary vitamin C intake and blood pressure (Beitz et al, 2003).

      • Similarly, another study demonstrated that tissue stores of vitamin C resulting from dietary intake alone were inversely correlated with DBP (Block et al, 2000).

      • Two randomized clinical trials of vitamin E supplementation for three to six months at daily doses of 200mg or 800mg reported a decrease in systolic blood pressure with smaller reductions in diastolic blood pressure in normotensive or mildly hypertensive adults (Boshtam et al, 2002; Schutte et al, 2004).

      • Two trials failed to demonstrate an effect of vitamin E on blood pressure (Palumbo et al, 2000; Farvid et al, 2004).

      • A longitudinal study indicated dietary vitamin E was associated with a reduced risk for hypertension (Mishra et al, 2004).

      • However, a cross sectional study reported increased serum vitamin E levels were associated with increased risk for hypertension (Chen et al, 2004).

    • Recommendation Strength Rationale

      • Both Conclusion Statements are Grade III

    • Minority Opinions

      Consensus reached.