DASHing toward lower blood pressure

Over one billion^[1] adults suffer from high blood pressure, or hypertension, worldwide. It affects one in four men and one in five women. Heart disease is the number one^[2] cause of death in the world, and hypertension is one of its leading risk factors^[3]. The global direct medical costs^[4] of hypertension are estimated at $370 billion per year, while savings from effective management of blood pressure are projected at about $100 billion per year.

Current management and treatment for hypertension commonly involves medication, supplements, and/or lifestyle changes. The average reductions in systolic and diastolic blood pressure for antihypertensive drugs, supplements, diets, and exercise have been reported^[5] to be 9/5 mmHg, 4/2 mmHg, 6/4 mmHg, and 5/3 mmHg, respectively. While drugs are generally the most effective way to reduce blood pressure, adherence can be surprisingly low, reported at 18.8% of participants in one study^[6].

On the other hand, dietary approaches to reduce blood pressure (BP) are effective and have reported adherence levels of up to 95%^[7]. But, which dietary approach is best? Unfortunately, guidelines sometimes emphasize different aspects of diet, and are occasionally inconsistent with one another. For instance, the American Heart Association’s guidelines^[8] suggest that hypertensive and prehypertensive people should consume less alcohol and sodium and more fruits, vegetables, and low-fat dairy products. The European Society of Hypertension and European Society of Cardiology^[9] guidelines, on the other hand, includes extra emphasis on reductions in saturated fat and cholesterol, accompanied by increases in fiber and plant protein.

These inconsistencies become all the more obvious when considering all the different dietary approaches that exist in the context of blood pressure reduction. To list a few, the Dietary Approaches to Stop Hypertension (DASH) diet^[10], the Mediterranean diet^[11], and a simple low-sodium diet all have evidence suggesting they have some impact on BP. Are all of these equally effective? The study under review sought to answer this question by performing a network meta-analysis of randomized controlled trials (RCTs) comparing anti-hypertensive diets.

The prevalence of hypertension is high and increasing, impacting global mortality and health costs. A variety of diets are recommended for and have demonstrated efficiency at lowering blood pressure. The study under review was designed to compare these diets, so as to establish a clinically meaningful hierarchy of antihypertensive dietary patterns.