The effect of dietary approaches to stop hypertension (DASH) on serum inflammatory markers: A systematic review and meta-analysis of randomized trials

Background & aims: Dietary approaches to stop hypertension (DASH) diet is associated with improved blood pressure and risk of cardiovascular diseases. It is proposed that DASH might also improve systemic inflammatory markers like highly sensitive C-reactive protein (hs-CRP); however, interventional studies have led to conflicting results. The aim of current systematic review was to summarize results of randomized clinical trials examining the effect of DASH on inflammatory biomarkers.

Methods: Randomized trials which assessed the effect of adherence to DASH diet on the circulating inflammatory biomarkers in adults were identified through searching PubMed, EMBASE, Scopus and Google Scholar up to December 2016. Difference in Mean change and its corresponding standard deviation in inflammatory markers between intervention and control groups were calculated to be used as effect size. Random effects model was used to calculate the summary effects.

Results: Seven trials were eligible and six studies with 451 participants were included in the meta-analysis which measured hs-CRP as the biomarker of systemic inflammation. The DASH diet significantly decreased serum hs-CRP levels [mean difference (MD) = -1.01, 95% confidence interval (CI): -1.64, -0.38; I-squared (I²) = 67.7%] compared to usual diets; however, the effect was not significant when it was compared with healthy diets (MD = 0.10 mg/L; 95%CI: -0.16, 0.37; I² = 94.0%). The reduction in serum hs-CRP levels was greater in trials lasted eight weeks or more.

Conclusion: Adherence to DASH diet is effective in improving circulating serum inflammatory biomarkers in adults, compared with usual diet; therefore, it could be a valuable strategy to suppress inflammation process.