DASH Works Better with Exercise and Weight Loss

 Salt reduction is essential for preventing and lowering elevated blood pressure (BP) and reducing CVD risk it. However, weight loss and a healthier DASH-diet are also important for lowering elevated BP. A study of 144 free-living overweight and obese subjects with elevated BP compared the impact of the DASH diet alone (DASH-A) or combined with exercise and weight loss (DASH-WM) with a control group that were advised not to change their diet or lose weight (UC). The subjects had an initial systolic BP = 130-159mmHg and a diastolic BP = 85-99mmHg but none were taking or started on BP-drugs during the 4 month study period. The DASH diet used in this study only reduced sodium to about 1.2mg sodium/kcal and the urinary sodium excretion data indicated dietary sodium intake was only reduced about 14% in the DASHA group and 21% in the DASH -WM group compared to the UC group that maintained their normal diet. The DASH-WM group was instructed to reduce their energy intake by about 500kcal/day. DASH-WM lowered BP significantly by 16.1/9.9mmHg over 4 months while the DASH-A group also experienced a significant BP reduction of 11.2/7.5mmHg on average. By contrast, the UC group experienced an average BP reduction of only 3.4/3.8mmHg after 4 months. 1 In addition to significant reductions in BP in the two DASH diet groups compared to the UC group this study also demonstrated that left ventricular hypertrophy (LVH) was significantly reduced in both DASH groups albeit more in the DASH-WH than the DASH-A. This is important as LVH is the single greatest risk factor for heart disease. LVH develops in part due to stiffened arteries. Pulse wave velocity (a measure of artery stiffness) was reduced significantly in both DASH diet groups compared to the control group albeit more so in the DASH-WM. The reduction in BP seen in this study was comparable to that seen with a high dose of the best antihypertensive drugs. This study demonstrates that dietary counseling and exercise classes are as effective for lowering BP and reducing artery stiffness and LVH as drugs.

The authors note that despite the effectiveness of the diet and lifestyle interventions might be difficult to implement in clinical settings. True enough but is this not so in part because few health insurance (public and private) currently pay for even a single dietary consult or even group classes for people who are overweight and have hypertension? Nor will most health insurance pay for exercise classes or a personal trainer. There is something fundamentally wrong with a healthcare system that pays billions for medical doctor office visits and billions more dollars for drugs to treat hypertension but pays next to nothing for dietary counseling or exercise classes so patients can learn how to reverse their own disease with a healthy diet and exercise program.

By James J. Kenney, PhD, RD, FACN?

1. Blumenthal J. et al. Arch Intern Med 2010;170:126-35