Johns Hopkins Health Alert
How a Vegetable-Rich Diet Lowers Blood Pressure
Clinical trials show that the DASH (Dietary Approaches to Stop Hypertension) eating plan can have a beneficial effect on blood pressure. In individuals with high blood pressure, it lowers systolic blood pressure by 11 mm Hg -- as much as taking a single blood pressure drug. The DASH diet is rich in fruits, vegetables, and low-fat dairy products and low in saturated fat and cholesterol. It also includes whole grains, fish, poultry, and nuts, but red meat, sweets, and sugary beverages are kept to a minimum.
How exactly how does a vegetable-rich diet help protect against high blood pressure? According to a British study reported in the journal Hypertension (volume 51, page 784), it may have to do in part with a substance called inorganic nitrate.
Fourteen healthy volunteers with normal blood pressure were randomly assigned to drink either half a quart of beetroot juice or water. Beetroot juice, like green leafy vegetables, is rich in inorganic nitrate, which gets converted to nitrite in your saliva. Once in your stomach, nitrite is converted to nitric oxide, a substance that helps blood vessels relax, leading to lower blood pressure levels.
Before the experiment, all of the participants had similar blood pressure and blood nitrate and nitrite levels. But within 30 minutes, nitrite levels were 16 times higher in the beetroot-juice group than in the water group. And after about three hours, blood pressure was 10/8 mm Hg lower in the people who drank the beetroot juice.
However, participants who drank beetroot juice but spit out their saliva for the next three hours, thus preventing nitrite from entering the body, saw no decrease in their blood pressure. Nitrate isn't the only reason why a vegetable-rich diet helps lower blood pressure. Vegetables are low in sodium, and their high potassium content helps to counter the negative effects of a high-salt diet -- yet more reasons to add more vegetables to your diet.
Posted in Hypertension and Stroke on June 1, 2010
Reviewed January 2011
Medical Disclaimer: This information is not intended to substitute for the advice of a physician. Click here for additional information: Johns Hopkins Health Alerts Disclaimer
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