High Blood Pressure
Ascorbic acid status and subsequent diastolic and systolic blood pressure.
Block G; Mangels AR; Norkus EP; Patterson BH; Levander OA; Taylor
Hypertension 2001 Feb;37(2):261-7
Free radicals and oxidation are involved in several aspects of blood
pressure physiology. We investigated the relationship between blood pressure
and antioxidants, including plasma ascorbic acid (AscA), in a 17-week
controlled-diet study. Study subjects included 68 men aged 30 to 59 years
who had a mean diastolic blood pressure of 73.4 mm Hg and a mean systolic
blood pressure of 122.2 mm Hg. One month of vitamin C depletion was followed
by 1-month repletion with 117 mg/d, repeated twice. All food and drink
were provided in the study. Subjects did not smoke or drink alcohol, all
consumed fruits and vegetables, and body weight was maintained. Plasma
was assayed periodically for AscA, alpha-tocopherol, carotenoids, and
lipids. Plasma AscA was inversely related to diastolic blood pressure
1 month later (correlation -0.48, P:<0.0001). Persons in the bottom
fourth of the plasma AscA distribution had >7 mm Hg higher diastolic
blood pressure than did those in the top fourth of the plasma AscA distribution.
Multivariate analysis with control for age, body mass index, other plasma
antioxidants, and dietary energy, calcium, fiber, sodium, and potassium
did not reduce the plasma AscA effect. One fourth of the variance in diastolic
blood pressure was accounted for by plasma AscA alone. Plasma AscA was
also significantly associated with systolic blood pressure in logistic
regression. Vitamin C may be an important component of the effectiveness
of fruits and vegetables in the reduction in blood pressure, and tissue
AscA levels may be important in the maintenance of low blood pressure.
Long-term intervention studies are warranted.