Vitamin B Supplementation, Homocysteine Levels, and
the Risk of Cerebrovascular Disease
A meta-analysis published in Neurology indicates that Vitamin B supplementation to lower homocysteine levels significantly reduces the incidence of stroke events.
Objective: To perform a meta-analysis on the effect of lowering homocysteine levels via B vitamin supplementation on cerebrovascular disease risk.
Methods: Using clinical trials published before August 2012 to assess stroke events, we used relative risks (RRs) with 95% confidence intervals (95% CIs) to measure the association between B vitamin supplementation and endpoint events using a fixed-effects model and χ2 tests. We included 14 randomized controlled trials with 54,913 participants in this analysis.
Results: We observed a reduction in overall stroke events resulting from reduction in homocysteine levels following B vitamin supplementation (RR 0.93; 95% CI 0.86–1.00; p = 0.04) but not in subgroups divided according to primary or secondary prevention measures, ischemic vs hemorrhagic stroke, or occurrence of fatal stroke.
There were beneficial effects in reducing stroke events in subgroups with ≥3 years follow-up time, and without background of cereal folate fortification or chronic kidney disease (CKD). Some trials that included CKD patients reported decreased glomerular filtration rate with B vitamin supplementation.
We conducted detailed subgroup analyses for cyanocobalamin (vitamin B12) but did not find a significant benefit regarding intervention dose of vitamin B12 or baseline blood B12 concentration.
Stratified analysis for blood pressure and baseline participant medication use showed benefits with >130 mm Hg systolic blood pressure and lower antiplatelet drug use in reducing stroke risk.
Conclusions: B vitamin supplementation for homocysteine reduction significantly reduced stroke events, especially in subjects with certain characteristics who received appropriate intervention measures.
- Yan Ji, MD,
- Song Tan, MD,
- Yuming Xu, MD,
- Avinash Chandra, MD,
- Changhe Shi, MD,
- Bo Song, MD,
- Jie Qin, MD and
- Yuan Gao, MD
Vitamin B-12 Fact Sheet
The Top 10 Foods Highest In Vitamin B-12
Vitamin D supplements significantly reduced blood pressure in the first large controlled study of African-Americans, researchers report in the American Heart Association journal Hypertension.
In the prospective trial, a three-month regimen of daily vitamin D increased circulating blood levels of vitamin D and resulted in a decrease in systolic blood pressure ranging from .7 to four mmHg (depending upon the dose given), compared with no change in participants who received a placebo.
Systolic blood pressure, the top and highest number in a reading, is pressure in the arteries when the heart beats. Diastolic blood pressure, the bottom and lower number, is pressure in the arteries between heart beats.
“Although this needs to be studied further, the greater prevalence of vitamin D deficiency among African-Americans may explain in part some of the racial disparity in blood pressure,” said John P. Forman, M.D., M.Sc., lead author of the study and Assistant Professor of Medicine in the Renal Division and Kidney Clinical Research Institute at Brigham and Women’s Hospital in Boston, Mass.
African-Americans have higher rates of hypertension and lower levels of circulating 25-hydroxyvitamin D (vitamin D3 or cholecalciferol) than the rest of the U.S. population. Few studies have included enough African-Americans to determine whether vitamin D supplements might reduce the racial disparity.
To explore this, researchers from seven major teaching hospitals conducted a four-arm, randomized, double-blinded study of 250 black adults. They tested blood pressure after a three-month regimen of daily vitamin D supplementation at one of three doses, and compared the findings with a group taking placebo vitamins:
- Taking 1,000 units of vitamin D each day for three months was associated with a .7 mm Hg decrease in systolic blood pressure.
- Taking 2,000 units was linked to a 3.4 mm Hg decrease.
- Taking 4,000 units netted a 4 mm Hg drop.
- Participants taking placebo supplements had an average increase of 1.7 mm Hg.
“The gains we saw were significant but modest,” Forman said.
Furthermore, diastolic blood pressure didn’t change in any of the four groups.
In prospective studies, lower blood levels of 25-hydroxyvitamin D have been independently linked with an increased risk of developing hypertension.
“If vitamin D supplementation lowered blood pressure among African-Americans, its widespread use could have major public health benefits,” said Andrew T. Chan, M.D., M.P.H., co-author of the study and Assistant Professor of Medicine in the Division of Gastroenterology at Massachusetts General Hospital.
Co-authors are: Jamil B. Scott, M.P.H., Ph.D.; Kimmie Ng, M.D., M.P.H.; Bettina F. Drake, Ph.D., M.P.H.; Elizabeth Gonzalez Suarez, M.A.; Douglas L. Hayden, M.A.; Gary G. Bennett, Ph.D.; Paulette D. Chandler, M.D., M.P.H.; Bruce W. Hollis, Ph.D.; Karen M. Emmons, Ph.D.; Edward L. Giovannucci, M.D., Sc.D.; and Charles S. Fuchs, M.D., M.P.H.
Full bibliographic information The American Heart Association journal Hypertension.
Effect of Vitamin D Supplementation on Blood
Pressure in Blacks
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BALTIMOREâ€”Vitamin C supplementation reduced both systolic and diastolic blood pressure, at least in short-term trials, according to a new meta-analysis from Johns Hopkins School of Medicine (Am J Clin Nutr. 2012 Apr 4).
The systematic review and meta-analysis included clinical trials researchers found by searching Medline, EMBASE and Central databases from 1966 to 2011. To be included in the analysis, studies must have been randomized controlled trials at least two weeks long focusing on effects on systolic blood pressure or diastolic blood pressure or both using oral vitamin C and concurrent control groups.
The researchers included 29 trials tfor the primary analysis with a median dose of 500 mg/d (about five times the recommended daily requirement), a median duration of eight weeks, and trial sizes ranging from 10 to 120 participants.
The pooled changes in systolic blood pressure and diastolic blood pressure were -3.84 mm Hg (P<0.01) and -1.48 mm Hg (P=0.04), respectively. In trials with hypertensive participants, corresponding reductions in systolic blood pressure and diastolic blood pressure were -4.85 mm Hg (P<0.01) and -1.67 mm Hg (P=0.17). By comparison, author leader Edgar â€œPete” R. Miller III, M.D., Ph.D., Â said patients who take blood pressure medication such as ACE inhibitors or diuretics can expect a roughly 10 millimeter of mercury reduction in blood pressure.
After the inclusion of nine trials with imputed blood pressure effects, blood pressure effects were attenuated, but remained significant.
â€œAlthough our review found only a moderate impact on blood pressure, if the entire U.S. population lowered blood pressure by 3 ml of mercury, there would be a lot fewer strokes,” said Miller, associate professor in the division of general internal medicine at the Johns Hopkins University School of Medicine. Miller cautioned, however, that none of the studies his team reviewed show that vitamin C directly prevents or reduces rates of cardiovascular disease (CVD), including stroke.
â€œOur research suggests a modest blood pressure lowering effect with vitamin C supplementation, but before we can recommend supplements as a treatment for high blood pressure, we really need more research to understand the implications of taking them,” Miller said.
Roughly 30 percent of adults in the United States have high blood pressure, or hypertension, an important risk factor for heart disease and stroke.