(LifeWire) - The DASH diet -- Dietary Approaches to Stop Hypertension -- has been promoted as a way to halt unhealthy high blood pressure for many years now. If you or a loved one has hypertension, chances are your doctor has told you about it.
But the DASH diet can do more than just lower blood pressure: In the last decade, studies have shown that the dietary approach can also lower cholesterol levels.
Basics of the DASH Diet
The DASH diet, which was developed by the National Institutes of Health, involves increasing fruit and vegetable intake within the parameters of a diet that limits the number of calories ingested per day. In its recommendations, the plan is similar to the food pyramid guide we’ve been exposed to since childhood.
Here are some of the basic requirements of the diet plan:
- Fruit: 4 to 5 daily servings
- Vegetables: 4 to 5 daily servings
- Dairy: 2 to 3 low-fat daily servings
- Grains: 7 to 8 daily servings
- Meat/fish: 2 daily servings
- Fats/oils: 2 to 3 daily servings
- Beans/nuts/seeds: 4 to 5 weekly servings
- Sweets: 5 weekly servings (at most)
The goal, according to the NIH, is to limit daily sodium to 2,300 milligrams and not allow saturated fat to make up more than 6% or total fat to make up more than 27% of your total daily caloric intake. Carbohydrate intake should be limited to 55% of your total calories for the day.
Blood Pressure, Cholesterol and DASH
Many studies have shown that the DASH diet is effective in reducing blood pressure. In fact, the NIH says the diet can reduce blood pressure in just 14 days.
A study of 116 people with borderline high blood pressure found that men and women on the DASH diet experienced significantly lower blood pressure than those on a control diet. Blood pressure, which is measured in millimeters of mercury (mmHg), indicates the pressure blood is exerting on the walls of blood vessels.
According to the 2005 study, systolic blood pressure (measured when the heart is contracting) dropped 12 mmHg in men and 11 mmHg in women. Diastolic pressure (measured when the heart is relaxing) dropped 6 mmHg in men and 7 mmHg in women during the 6-month trial period.
The research isn’t as clear when it comes to cholesterol and the DASH diet.
Cholesterol lab results typically are reported as two numbers: HDL (high-density lipoproteins) and LDL (low-density lipoproteins). HDL is considered “good cholesterol” and clears extra cholesterol from the blood vessels, whereas LDL, "bad cholesterol," deposits cholesterol in the blood vessels. Cholesterol is measured in milligrams per deciliter, or mg/dL.
One study of 436 people found that the DASH diet significantly affected cholesterol levels.
The study reported that compared to those on a control diet, DASH dieters saw a decrease in both HDL and LDL levels. Those with high levels of HDL cholesterol were affected by the decrease more than those with low HDL levels.
However, other studies have found that DASH-dieters' HDL levels increased, on average.
Talk to Your Doctor
Before beginning the DASH diet or making any other dietary changes, talk to your doctor. He or she should look at your cholesterol numbers and evaluate whether dietary changes could make a difference for you. You can also talk to your doctor about HDL levels and any concerns you may have about the effect of the DASH diet.
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"Your Guide to Lowering Your Blood Pressure with DASH." Nhlbi.nih.gov. 2006. National Heart Lung and Blood Institute. 27 Aug. 2008 <www.nhlbi.nih.gov/health/public/heart/hbp/dash/new_dash.pdf>.