Vitamin C can reduce high blood pressure, study finds

December 19, 1999

CORVALLIS, Ore. - Researchers have discovered that a 500 milligram daily supplement of vitamin C can reduce high blood pressure in hypertensive patients.

The study, published this month in the medical journal Lancet, was done by scientists at the Boston University School of Medicine and the Linus Pauling Institute at Oregon State University. It was supported by the National Heart, Lung and Blood Institute of the National Institutes of Health.

"Hypertension is a serious health problem in much of the world," said Balz Frei, professor and director of the Linus Pauling Institute, and a co-author of the research along with principal investigator Dr. Joseph Vita at Boston University. "It's a key risk factor in heart disease and strokes."

"We believe this is a significant finding that may be of considerable value to patients who have moderately elevated blood pressure," Frei said. "Working with their doctors, it may provide a way to bring their blood pressure back within acceptable levels without the cost or possible side effects of prescription drugs."

The amount of vitamin C used to produce the blood pressure reductions found in the study - 500 milligrams per day - would be without any side effects, very inexpensive as a dietary supplement, and may produce other health benefits as well, Frei said, especially if it was at least partially obtained by eating an improved diet rich in fruits and vegetables.

In this placebo-controlled, double-blind study, scientists worked with 45 patients with differing characteristics - different age, sex, race, smoker status, etc. - but who all had high blood pressure, defined as a diastolic blood pressure of more than 90 mm Hg. Some people who had more serious health problems such as diabetes or coronary artery disease were excluded. Patients who were taking medications to control their blood pressures discontinued those prescriptions long enough before tests were made so that they wouldn't interfere with the results of the study.

An "acute" dosage of 2,000 milligrams of vitamin C was not found to have a significant immediate impact on blood pressure when it was measured two hours after the dose.

However, with the long term dosages of 500 milligrams of vitamin C per day, the systolic, diastolic and mean blood pressures all declined about 9 percent, measured one month after the vitamin C intake began. In general terms, this meant systolic pressure dropped from 155 to 142; diastolic from 87 to 79; and mean blood pressure from 110 to 100 mm Hg.

The drop in diastolic blood pressure was less statistically significant, Frei said, because in that measurement people taking placebo pills also had a modest drop in blood pressure. And intakes of vitamin C do not appear to have any effect in lowering the blood pressure of people whose levels are already normal.

In their report, the scientists said the mechanisms for the drop in blood pressure is still not certain.

"One theory that could explain the results is that vitamin C works as an antioxidant in the human body," Frei said. "In doing that, it would help protect the body's level of nitric oxide, which is important to blood vessel function."

Nitric oxide, he said, is a natural compound in the body that relaxes blood vessels and contributes to the body maintaining a normal, healthy blood pressure, Frei said. But under oxidative stress, nitric oxide may become inactivated or inhibited. An intake of vitamin C somewhat higher than normal may help protect the levels of nitric oxide and allow it to perform its natural functions, Frei said.

Other metabolic mechanisms may also be at work in this process which are not yet fully understood, the scientists said. And they caution that people with more seriously elevated blood pressure may still need to incorporate other medications or lifestyle changes in close consultation with their doctors.

Confirmation of these findings in larger studies is recommended, the researchers said, although there already appears to be solid evidence from studies such as this and epidemiological analysis that vitamin C may have value in the clinical treatment of high blood pressure.

Related studies were also published last year in Circulation and other professional journals. In them, Frei, Vita and other scientists found that moderate daily supplements of vitamin C could improve endothelial function - the "relaxation" state of blood vessels - and thereby help prevent the chest pains of unstable angina pectoris and reduce the risk of heart attack and stroke. The dosage in that case - 500 milligrams per day - was the same as in the current research.

Frei and other experts at OSU's Linus Pauling Institute have also recently called for the recommended dietary allowance of vitamin C, even for healthy individuals, to be officially doubled to 120 milligrams per day, as evidence continues to emerge about the important health benefits it may have at higher levels than those once considered adequate to prevent the disease of scurvy.

A federal panel is at the moment considering these proposed changes for RDAs of vitamin C and other antioxidant vitamins.
-end-
By David Stauth, 541-737-0787
SOURCE: Balz Frei, 541-737-5078

Oregon State University

Related Blood Pressure Articles from Brightsurf:

Children who take steroids at increased risk for diabetes, high blood pressure, blood clots
Children who take oral steroids to treat asthma or autoimmune diseases have an increased risk of diabetes, high blood pressure, and blood clots, according to Rutgers researchers.

High blood pressure treatment linked to less risk for drop in blood pressure upon standing
Treatment to lower blood pressure did not increase and may decrease the risk of extreme drops in blood pressure upon standing from a sitting position.

Changes in blood pressure control over 2 decades among US adults with high blood pressure
National survey data were used to examine how blood pressure control changed overall among U.S. adults with high blood pressure between 1999-2000 and 2017-2018 and by age, race, insurance type and access to health care.

Transient increase in blood pressure promotes some blood vessel growth
Blood vessels are the body's transportation system, carrying oxygen and nutrients to cells and whisking away waste.

Effect of reducing blood pressure medications on blood pressure control in older adults
Whether the amount of blood pressure medications taken by older adults could be reduced safely and without a significant change in short-term blood pressure control was the objective of this randomized clinical trial that included 534 adults 80 and older.

Brain blood flow sensor discovery could aid treatments for high blood pressure & dementia
A study led by researchers at UCL has discovered the mechanism that allows the brain to monitor its own blood supply, a finding in rats which may help to find new treatments for human conditions including hypertension (high blood pressure) and dementia.

Here's something that will raise your blood pressure
The apelin receptor (APJ) has been presumed to play an important role in the contraction of blood vessels involved in blood pressure regulation.

New strategy for treating high blood pressure
The key to treating blood pressure might lie in people who are 'resistant' to developing high blood pressure even when they eat high salt diets, shows new research published today in Experimental Physiology.

Arm cuff blood pressure measurements may fall short for predicting heart disease risk in some people with resistant high blood pressure
A measurement of central blood pressure in people with difficult-to-treat high blood pressure could help reduce risk of heart disease better than traditional arm cuff readings for some patients, according to preliminary research presented at the American Heart Association's Hypertension 2019 Scientific Sessions.

Heating pads may lower blood pressure in people with high blood pressure when lying down
In people with supine hypertension due to autonomic failure, a condition that increases blood pressure when lying down, overnight heat therapy significantly decreased systolic blood pressure compared to a placebo.

Read More: Blood Pressure News and Blood Pressure Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.