Featured Research

from universities, journals, and other organizations

Big doses of vitamin C may lower blood pressure

Date:
April 18, 2012
Source:
Johns Hopkins Medicine
Summary:
Taking large doses of vitamin C may moderately reduce blood pressure, according to an analysis of years of research. But the researchers stopped short of suggesting people load up on supplements.

Taking large doses of vitamin C may moderately reduce blood pressure, according to an analysis of years of research by Johns Hopkins scientists. But the researchers stopped short of suggesting people load up on supplements.

"Our 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," says Edgar "Pete" R. Miller III, M.D., Ph.D., an associate professor in the division of general internal medicine at the Johns Hopkins University School of Medicine and leader of the study published in the American Journal of Clinical Nutrition.

Roughly 30 percent of adults in the United States have high blood pressure, or hypertension, an important risk factor for heart disease and stroke. Successful treatment may include drugs, exercise, weight loss, and dietary changes such as reducing salt intake. Some experts believe that large amounts of vitamin C, an essential micronutrient found primarily in fruits and vegetables, could lower pressure as well, but randomized, controlled dietary intervention studies -- the gold standard of nutrition research -- have produced mixed results.

Miller and his colleagues reviewed and analyzed data from 29 randomized, controlled, previously published clinical trials that reported systolic and/or diastolic blood pressure values and also compared vitamin C intake to a placebo. What they found is that taking an average of 500 milligrams of vitamin C daily -- about five times the recommended daily requirement -- reduced blood pressure by 3.84 millimeters of mercury in the short term. Among those diagnosed with hypertension, the drop was nearly 5 millimeters of mercury.

By comparison, Miller says, patients who take blood pressure medication such as ACE inhibitors or diuretics (so-called "water pills") can expect a roughly 10 millimeter of mercury reduction in blood pressure.

Five hundred milligrams of vitamin C is the amount in about six cups of orange juice. The recommended daily intake of vitamin C for adults is 90 milligrams.

"Although our review found only a moderate impact on blood pressure, if the entire U.S. population lowered blood pressure by 3 milliliters of mercury, there would be a lot fewer strokes," Miller says. Miller cautions, however, that none of the studies his team reviewed show that vitamin C directly prevents or reduces rates of cardiovascular disease, including stroke.

Scientists have focused on vitamin C's potential role in blood pressure reduction because of the nutrient's biological and physiological effects. For example, vitamin C may act as a diuretic, causing the kidneys to remove more sodium and water from the body, which helps to relax the blood vessel walls, thereby lowering blood pressure.

Nutritional supplements are a $28 billion-a-year industry, and marketing claims, newspaper stories and testimonials often make them hard to resist, Miller says. People often view supplements as a "natural alternative" and preferable to drugs for high blood pressure or other ailments, he adds, despite mounting evidence that many supplements don't work and in some cases may cause harm.

"People love to take vitamins regardless of the evidence or lack of it," Miller says. "We're trying to raise the bar and provide evidence-based guidance about whether supplements help or actually do harm." With respect to vitamin C, he says, the jury is still out.

Other study authors from Johns Hopkins include Stephen P. Juraschek, an M.D., Ph.D. candidate; Eliseo Guallar, M.D., Dr.Ph.; and Lawrence J. Appel, M.D., M.P.H.


Story Source:

The above story is based on materials provided by Johns Hopkins Medicine. Note: Materials may be edited for content and length.


Journal Reference:

  1. S. P. Juraschek, E. Guallar, L. J. Appel, E. R. Miller. Effects of vitamin C supplementation on blood pressure: a meta-analysis of randomized controlled trials. American Journal of Clinical Nutrition, 2012; DOI: 10.3945/ajcn.111.027995

Cite This Page:

Johns Hopkins Medicine. "Big doses of vitamin C may lower blood pressure." ScienceDaily. ScienceDaily, 18 April 2012. <www.sciencedaily.com/releases/2012/04/120418111810.htm>.
Johns Hopkins Medicine. (2012, April 18). Big doses of vitamin C may lower blood pressure. ScienceDaily. Retrieved July 22, 2014 from www.sciencedaily.com/releases/2012/04/120418111810.htm
Johns Hopkins Medicine. "Big doses of vitamin C may lower blood pressure." ScienceDaily. www.sciencedaily.com/releases/2012/04/120418111810.htm (accessed July 22, 2014).

Share This




More Health & Medicine News

Tuesday, July 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Gilead's $1000-a-Pill Drug Could Cure Hep C in HIV-Positive People

Gilead's $1000-a-Pill Drug Could Cure Hep C in HIV-Positive People

TheStreet (July 21, 2014) New research shows Gilead Science's drug Sovaldi helps in curing hepatitis C in those who suffer from HIV. In a medical study, the combination of Gilead's Hep C drug with anti-viral drug Ribavirin cured 76% of HIV-positive patients suffering from the most common hepatitis C strain. Hepatitis C and related complications have been a top cause of death in HIV-positive patients. Typical medication used to treat the disease, including interferon proteins, tended to react badly with HIV drugs. However, Sovaldi's %1,000-a-pill price tag could limit the number of patients able to access the treatment. TheStreet's Keris Lahiff reports from New York. Video provided by TheStreet
Powered by NewsLook.com
$23.6 Billion Awarded To Widow In Smoking Lawsuit

$23.6 Billion Awarded To Widow In Smoking Lawsuit

Newsy (July 20, 2014) Cynthia Robinson claims R.J. Reynolds Tobacco Company hid the health and addiction risks of its products, leading to the death of her husband in 1996. Video provided by Newsy
Powered by NewsLook.com
Tooth Plaque Provides Insight Into Diets Of Ancient People

Tooth Plaque Provides Insight Into Diets Of Ancient People

Newsy (July 19, 2014) Research on plaque from ancient teeth shows that our prehistoric ancestor's had a detailed understanding of plants long before developing agriculture. Video provided by Newsy
Powered by NewsLook.com
Contaminated Water Kills 3 Babies in South African Town

Contaminated Water Kills 3 Babies in South African Town

AFP (July 18, 2014) Contaminated water in South Africa's northwestern town of Bloemhof kills three babies and hospitalises over 500 people. The incident highlights growing fears over water safety in South Africa. Duration: 02:22 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins