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A condition called essential hypertension is the most commonly diagnosed disease among adults in the United States and in most countries around the world. Essential hypertension is high blood pressure without a single, discernible cause.
Essential hypertension may be caused by stiffened blood vessels that can no longer expand to accommodate additional blood flow during exercise or stress. Or it may be caused by "sticky" blood that tends to form clots.
Or it can result from imbalances in sodium and potassium, or infection, or it can result from an inability of the kidneys to remove sodium from the bloodstream so that it isn't necessary to dilute the blood plasma with fluid to keep sodium concentrations constant.
By the age of 30, hypertension is "established" in up to 40% of adults, and by the age of 50, hypertension begins to be complicated in up to 60% of adults, most of whom will eventually die of cardiovascular disease.
High blood pressure is the single most controllable cause of cardiovascular disease, and the DASH diet was devised to treat it without medication.
Dietary Approaches to Stop Hypertension
Because so many Americans still die of heart and vascular disease, the (US) National Heart, Lung, and Blood Institute devised a program called Dietary Approaches to Stop Hypertension, or DASH. While it is common to refer to this program as the "DASH diet," it is really just a pattern for choosing foods that help lower blood pressure.
These mineral elements are often in short supply in the American diet. No special foods or supplements are required. It is just necessary to eat 5 to 9 servings of fruit and vegetables per day, preferably including at least 1 or 2 fruit servings to provide enough potassium and 1 or 2 servings of leafy green vegetables to provide enough magnesium. The DASH diet does not require calcium supplements, but it permits the consumption of low-fat, low-salt dairy products.
The DASH approach is also designed to ensure that people don't receive too much sodium from added salt. Only a minority of people actually have a kind of sodium sensitivity that keeps the kidneys from pumping sodium out of the bloodstream so that diuretics are necessary to lower blood pressure. Nearly everyone who eats a lot of prepared foods and fast foods, however, gets so much sodium from salt that it begins to displace the potassium from fruits and vegetables.
The DASH approach cuts sodium consumption roughly in half, without forbidding any foods altogether.
How Effective Is the DASH Approach?
Just how much does the DASH diet lower blood pressure? If you don't already have high blood pressure, it only lowers your blood pressure a little, about 5 mm Hg (5 "points") for the systolic pressure (first number), and about 3 mm Hg (3 "points") for the diastolic pressure. If you already have hypertension, then the effects are more noticeable, about 11 points for systolic pressure and 5 points for diastolic pressure.
That's not a lot, but it is roughly the effect you get from a single dose of most high blood pressure medications. The advantage of the DASH approach is that there are no side effects, it doesn't cost anything extra, and it may prevent the progression of pre-hypertension to hypertension, saving you a lifetime of medical expense and increased risk of cardiovascular disease.