Despite the results, researchers are not suggesting that people increase their intake of vitamin C. More research is needed, they said.
“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,” said Dr. Edgar R. Miller III, an associate professor in the division of general internal medicine at the Johns Hopkins University School of Medicine. The study, led by Miller, was published in the American Journal of Clinical Nutrition.
Nearly one-third of adults in the United States has high blood pressure, which can lead to heart disease and stroke. Health authorities often recommend medication, exercising, losing weight and eating healthy foods with limited salt to treat hypertension.
Previous research has shown mixed results as to whether large amounts of vitamin C can affect blood pressure. But after Miller and his team analyzed 29 trials, they found that taking an average of 500 milligrams of vitamin C daily – more than fives times the recommended amount – reduced blood pressure by 3.84 millimeters of mercury in the short term. For those who had high blood pressure, the reduction was 5 millimeters.
It’s about half the effect patients experience by taking medication to lower their blood pressure, Miller 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,” the news release states.
The current recommended daily intake of vitamin C is 90 milligrams. Someone would have to drink six cups of orange juice to reach 500 milligrams, according to the press release.
“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 said.
Still, he cautioned that none of the studies his team reviewed show that vitamin C directly prevents or reduces rates of cardiovascular disease, including stroke.
Source: Johns Hopkins Medicine news release
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