The Cooper Institute
 

Founded in 1970 by the "Father of Aerobics"
Kenneth H. Cooper MD, MPH

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Need to Lower Your Resting Blood Pressure? DASH, Don’t Walk!

Posted in
Eat better

Monday, Apr 08, 2013

Hypertension is a major public health problem worldwide, with prevalence in the United States estimated at 78 million (33% of the adult population). Because it is a major risk factor for cardiovascular disease, identification and aggressive treatment of hypertension is of paramount importance. However, because most people with hypertension have no symptoms, it is estimated that 20% of hypertensive individuals are unaware of their condition. Thus, regular monitoring of resting blood pressure is one key for identifying and managing this very common condition.

Unless resting blood pressure is severely elevated, lifestyle changes are recommended as the initial treatment strategy for hypertension. Weight reduction, increased physical activity, and tobacco cessation, as well as dietary sodium reduction have all been shown to have favorable effects on blood pressure. In 1997, results from the DASH (Dietary Approaches to Stopping Hypertension) Study were first published. Briefly, DASH is an eating plan that emphasizes fiber-rich complex carbohydrates (fruits, vegetables, legumes, and whole grains) and low-fat dairy, along with reduced saturated fat and a moderate sodium intake. In this first study, following the DASH eating plan for 8-weeks resulted in a reduction of 11.4 and 5.5 mm Hg for systolic and diastolic blood pressure respectively in 326 hypertensive subjects. This reduction in blood pressure occurred in the absence of weight loss or physical activity. As a bonus, blood levels of LDL cholesterol were also reduced. The 2001 DASH-Sodium study used a similar approach, but manipulated sodium intake throughout the 90-day study. During the portion of the study where sodium was restricted the most (intakes of ~1500 mg/day), greater reductions in blood pressure were seen.  Later, Smith and colleagues showed that a DASH eating plan also resulted in improvements in cognitive function; we reported this previously.

Because none of the DASH studies up to that point had examined cardiovascular biomarkers of risk, Blumenthal and colleagues compared the effects of DASH-alone vs. DASH plus a weight management program vs. a control group in 144 overweight and sedentary subjects with high blood pressure.  During the 4-month study period, DASH-alone subjects were instructed not to exercise or lose weight, whereas the DASH weight management subjects attended weekly weight loss classes as well as supervised exercise sessions 3 times per week. The control group was asked to maintain their usual dietary and exercise habits. Accordingly, systolic blood pressure was reduced by 16, 11, and 3 mm Hg in the DASH weight management, DASH-alone, and control groups respectively. Physical fitness level and body weight changes were significantly more favorable in the DASH weight management group compared to the other two groups. Changes to several cardiovascular biomarkers were also examined in the three groups. For example, a flow-mediated dilation (FMD) test is an excellent way to assess artery health and function. During this test, a blood pressure cuff is placed on the upper arm, inflated to 200 mm Hg, and maintained at this level for 5 minutes. This process completely blocks the brachial artery.  Once the cuff is deflated, the speed and degree to which the brachial artery returns to its normal size is measured (faster is better). Both DASH groups improved significantly and to the same degree, while the control group improved much less. Another test called Pulse Wave Velocity (PWV) is an excellent indicator of arterial stiffness (healthy arteries are not stiff).  Both of the DASH groups improved significantly on the PWV test compared to the control group. Thus, the DASH approach resulted in healthier and more functional arteries.

To Summarize

1. DASH-alone significantly improves resting blood pressure.

2. Adding exercise and weight loss to a DASH eating plan leads to an even greater decrease in resting blood pressure. In fact, these improvements match what is often seen with an antihypertensive medication!

3. Although the precise mechanism is unknown, it is proposed that the high fiber, calcium, potassium, and magnesium content of a DASH eating plan help the arteries to relax, which in turn lowers blood pressure.

So get “dashing” to a lower blood pressure by applying some of the principles of the DASH eating plan today!

References

Appel, L. et al. (1997). A clinical trial of the effects of dietary patterns on blood pressure. DASH collaborative research group. N Engl J Med, 336(16), 1117-1124.

Blumenthal, J. et al. (2010). Effects of the DASH diet alone and in combination with exercise and weight loss on blood pressure and cardiovascular biomarkers in men and women with high blood pressure. Arch Intern Med, 170(2), 126-134.

Sacks, F. et al. (2001). Effects on blood pressure of reduced dietary sodium and the dietary approaches to stop hypertension (DASH) diet. DASH-Sodium collaborative research group. N Engl J Med, 344(1), 3-10.