INCREASED DIETARY PROTEIN INTAKE LOWERS BLOOD PRESSURE IN OVERWEIGHT SUBJECTS

Abstract

Objective: Several intervention trials have shown that diet composition affects blood pressure (BP). In this study we focused on the effect of dietary protein content on BP. Design and Method: In this randomized double-blind parallel group study, 94 adult untreated overweight subjects with mildly elevated BP (BMI 25-35 kg/m2, BP > 130/85 and <160/100 mm Hg) were included. After a 2-week run-in period on a weight-maintaining standardized diet (15 en% protein (P), 30 en% fat (F) and 55 en% carbohydrate (C)), subjects were randomized to a high P or a high C diet for 4 weeks. On the high C diet 60 g of C of the run-in diet was replaced by 3x20 g of maltodextrin supplements, on the high P diet 60 g of C was replaced by 3x20 g of a protein supplement (mixture of 20% pea, 20% soy, 30% egg and 30% milk protein isolate). Supplements were matched for Na, P, K, Ca and Mg content and taken with each meal. Office and 24-h ambulatory blood pressures (ABP) were assessed at the end of the run-in and after 4 weeks supplement use. BP differences between groups after 4 weeks were analyzed by ANCOVA with BP at the end of the run-in as covariate. Results :At the end of run-in office BP (mean ± SE) was 142.6 ± 1.6/92.2 ± 0.9 mm Hg in the C and 143.3 ± 1.8/92.9 ± 1.0 mm Hg in the P group; daytime ambulatory BPs were 147.5 ± 1.8/91.0 ± 1.1 mm Hg and 147.2 ± 1.8/92.5 ± 1.2 mm Hg respectively. After 4 weeks, office SBP and DBP were lower in the P than in the C group (-4.9 mm Hg (95% CI -1.5, -8.2), p = 0.005 and - 2.7 mm Hg (95% CI -0.1, -5.4), p = 0.045) and daytime ambulatory SBP tended to be (-4.1 mm Hg (95% CI + 0.2, -8.3), p = 0.06). No significant between-group differences in daytime ambulatory DBP (-1.7 mm Hg (95% CI + 1.3, -4.8), p = 0.26) or night-time BP were found. Conclusions: An increase in dietary protein content, in exchange for dietary carbohydrates (glucose), in a weight-maintaining diet lowers blood pressure in overweight subjects with mild blood pressure elevation.