Effect of legumes in energy reduced dietary approaches to stop hypertension (DASH) diet on blood pressure among overweight and obese type 2 diabetic patients: a randomized controlled trial

BACKGROUND: This study aimed to investigate the effects of legumes in dietary approaches to stop hypertension (DASH) on blood pressure and urinary sodium and potassium in participants with type 2 diabetes. We further investigated whether changes in individual dietary food groups in the DASH diet contribute to blood pressure. METHODS: Participants were randomized to the traditional DASH diet (n = 150) or the legume-based DASH diet (n = 150). Blood pressure and urinary sodium and potassium were measured at baseline and after 16-week interventions. An intention-to-treat approach with multiple imputations of missing data was applied. The restricted cubic spline (RCS) was applied to assess the linearity and explore the shape of the relationship between the changes in food groups and systolic blood pressure (SBP) in the two intervention groups. RESULTS: A reduction in SBP and urinary sodium was observed at week 16 in both dietary interventions, and this reduction was more significant in the legume-based DASH diet, than in the DASH diet. In the legume-based DASH diet, SBP decreased with the legume intake of more than 95.8 g/day (P nonlinear < 0.001). The multivariable RCS analysis showed a U-shaped relationship of refined grains, an L-shaped relationship of fruits, and a linear relationship of sweet, energy, sodium and vegetables intake with SBP. CONCLUSIONS: The DASH diet, enriched in legumes, could improve SBP in participants with type 2 diabetes. In DASH diet, the balance of consumption of refined grains and fruits along with higher vegetable consumption and lower sweet, sodium and energy intake reduced the SBP. Trial registration: IRCT20090203001640N17.