Abstract
: Nutr J. 2008 Dec 17;7(1):35. [Epub ahead of print] Links
Vitamin C in plasma is inversely related to blood pressure and change in blood pressure during the previous year in young Black and White women.Block G, Jensen CD, Norkus EP, Hudes M, Crawford PB.
ABSTRACT: BACKGROUND: The prevalence of hypertension and its contribution to cardiovascular disease risk makes it imperative to identify factors that may help prevent this disorder. Extensive biological and biochemical data suggest that plasma ascorbic acid may be such a factor. In this study we examined the association between plasma ascorbic acid concentration and blood pressure (BP) in young-adult women. METHODS: Participants were 242 Black and White women aged 18-21 yr from the Richmond, CA, cohort of the National Heart, Lung and Blood Institute Growth and Health Study. We examined the associations of plasma ascorbic acid with BP at follow-up year 10, and with change in BP during the previous year. RESULTS: In cross-sectional analysis, plasma ascorbic acid at year 10 was inversely associated with systolic BP and diastolic BP after adjusting for race, body mass index, education, and dietary intake of fat and sodium. Persons in the highest one-fourth of the plasma ascorbic acid distribution had 4.66 mmHg lower systolic BP (95% CI 1.10 to 8.22 mmHg, p=0.005) and 6.04 mmHg lower diastolic BP (95% CI 2.70 to 9.38 mmHg, p=0.0002) than those in the lowest one-fourth of the distribution. In analysis of the change in BP, plasma ascorbic acid was also inversely associated with change in systolic BP and diastolic BP during the previous year. While diastolic blood pressure among persons in the lowest quartile of plasma ascorbic acid increased by 5.97 mmHg (95% CI 3.82 to 8.13 mmHg) from year 9 to year 10, those in the highest quartile of plasma vitamin C increased by only 0.23 mmHg (95% CI -1.90 to +2.36 mmHg) (test for linear trend: p<0.0001). A similar effect was seen for change in systolic BP, p=0.005. CONCLUSIONS: Plasma ascorbic acid was found to be inversely associated with BP and change in BP during the prior year. The findings suggest the possibility that vitamin C may influence BP in healthy young adults. Since lower BP in young adulthood may lead to lower BP and decreased incidence of age-associated vascular events in older adults, further investigation of treatment effects of vitamin C on BP regulation in young adults is warranted.
1: Ann N Y Acad Sci. 2002 Apr;959:180-7. Links
Ascorbic acid, blood pressure, and the American diet.Block G.
School of Public Health, University of California, Berkeley, California 94720, USA. gblock@uclink4.berkeley.edu
A large controlled study supported by the NIH, the DASH study (Dietary Approaches to Stop Hypertension), demonstrated that a diet rich in fruits and vegetables can reduce blood pressure in persons with moderate elevation in blood pressure (BP). Fruits and vegetables are important sources of antioxidants such as vitamin C and carotenoids. We conducted a study in which we fed people a diet deficient in vitamin C for 30 days, followed for another 30 days by a diet adequate in vitamin C. Their blood levels of vitamin C and blood pressure (BP) were tracked. Plasma vitamin C was inversely related to diastolic blood pressure one month later (correlation = -0.48, P < 0.0001). Persons whose blood levels of vitamin C went down the furthest on depletion had the highest blood pressure one month later. Persons in the lowest one-fourth of the plasma vitamin C distribution had diastolic BP 7 mm Hg higher than did those in the upper one-fourth of the plasma ascorbic acid distribution. Multivariate control for age, body mass index, other plasma antioxidants, and dietary energy, calcium, fiber, sodium, and potassium did not reduce the plasma vitamin C effect. We believe that this indicates that the tissue stores of vitamin C may be important in regulating blood pressure. It is often thought that Americans' intake of vitamin C is ample, since the average intake is about 100 mg/day. However, this average level obscures the fact that substantial numbers of people actually have habitually low intake levels and low blood levels. African Americans tend to have low blood levels of vitamin C as well as the highest risk of hypertension. Low intake of antioxidant-rich fruits and vegetables may be one of the causes of hypertension.
1: Hypertension. 2001 Feb;37(2):261-7. Links
Comment in:
Hypertension. 2001 Feb;37(2):268-9.
Ascorbic acid status and subsequent diastolic and systolic blood pressure.Block G, Mangels AR, Norkus EP, Patterson BH, Levander OA, Taylor PR.
National Cancer Institute, Bethesda, MD, USA.
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.
Pomegranate juice also lowers blood pressure via natural ACE inhibitors
