Pooling 10 randomized trials (22 in the qualitative synthesis), the DASH diet did not lower blood pressure significantly more than comparator diets: systolic difference 1.30 mmHg (95% CI -1.54 to 4.14), diastolic 0.21 mmHg (-3.72 to 4.14), with substantial heterogeneity. DASH did outperform on secondary markers: LDL cholesterol fell 8.59 mg/dL, HbA1c dropped 0.49 points, urinary sodium declined and urinary potassium rose. Certainty of evidence ranged from moderate to very low.
The null blood pressure result should not be read as DASH failing. The comparators were other structured diets, not usual Western eating, and the original DASH trials showed clear reductions against a control diet. The likelier message is that several well-designed patterns, such as Mediterranean, low-sodium, or plant-forward approaches, lower blood pressure by overlapping routes: more potassium, less sodium, better weight control. Wide confidence intervals spanning roughly 4 mmHg in either direction mean the analysis cannot rule out a meaningful difference, and with only 10 pooled trials of mixed design, it was underpowered to settle the question. The HbA1c CI is suspiciously narrow, which hints at one dominant study rather than a robust consensus.
For readers, the practical takeaway is adherence over branding. Any structured diet that cuts sodium, raises potassium-rich produce, and improves lipids likely helps, and DASH's lipid and glycemic signals are a bonus. This is a confirmatory, low-certainty analysis, not a reason to abandon DASH.