Dietary protein and soluble fiber reduce ambulatory blood pressure in treated hypertensives

In population studies, higher blood pressure has been associated with lower intake of protein and, possibly, lower fiber consumption. In the present r andomized controlled trial, we sought to determine whether dietary protein and fiber had additive effects on blood pressure reduction in hypertensives . Treated hypertensive patients changed for 4 weeks (familiarization) to a diet low in protein (12.5% energy) and fiber (15 g/d). Patients (n=41) were then randomized to 1 of 4 groups in an 8-week factorial study of parallel design in which they continued the low-protein, low-fiber diet alone or had supplements of soy protein to increase protein intake to 25% energy, of ps yllium to provide an additional 12 g soluble fiber/d, or of both protein an d fiber. The 24-hour ambulatory blood pressure was compared from the end of familiarization to the end of intervention. In the 36 subjects who provide d complete data, protein and fiber had significant additive effects to lowe r 24-hour and awake systolic blood pressure. Relative to control subjects, the net reduction in 24-hour systolic blood pressure was 5.9 mm Hg with fib er and with protein. Findings were independent of age, gender, and change i n weight, alcohol intake, or urinary sodium and potassium. Relative to redu ced fiber and protein intake, dietary protein and soluble fiber supplements lower blood pressure additively in hypertensives. These findings have impo rtant implications for the prevention and management of hypertension, parti cularly in populations in which high blood pressure is prevalent in associa tion with diets low in protein, fiber, or both.