Dietary Approaches to Stop Hypertension (DASH) for the primary and secondary prevention of cardiovascular diseases.
Level 1 - systematic review of randomized trials
Systematic review of randomized controlled trials
PubMed 40326569 · doi:10.1002/14651858.CD013729.pub2
What was done
This Cochrane systematic review searched literature through May 2024 for randomized controlled trials evaluating the DASH diet for primary or secondary cardiovascular disease (CVD) prevention. Eligible studies had interventions lasting at least 8 weeks with follow-up of at least 3 months, comparing DASH against no intervention (or usual care), minimal intervention (brief advice/leaflets), or other dietary interventions. Primary outcomes were myocardial infarction, heart failure, and stroke; secondary outcomes included mortality, revascularisation, blood pressure, lipid changes, and adverse effects, evaluated using GRADE.
What was found
Five RCTs involving 1,397 participants (1,075 in eligible comparative arms) were included; all evaluated primary prevention in adults without diagnosed CVD, with follow-ups between 16 weeks and 18 months. When comparing DASH to no intervention, one trial (n = 144) reported zero myocardial infarctions and zero strokes over 1 year (low certainty), and one trial (n = 90) reported zero deaths at 6 months (very low certainty). For DASH versus minimal intervention, two trials (n = 629) found no clear difference in myocardial infarction over 1 year (RR 2.99, 95% CI 0.12 to 73.04; low certainty) and zero strokes (low certainty). For DASH versus another diet, one trial (n = 261) found no clear difference in all-cause mortality over 1 year (RR 2.98, 95% CI 0.12 to 72.42; very low certainty). Abstract reports indicate possible improvements in blood pressure, total cholesterol, triglycerides, and HDL compared to control, with little effect on LDL, but numerical values for these surrogates were not provided.
Why it matters
Although the DASH diet is widely recommended based on improvements in intermediate biomarkers like blood pressure, direct randomized trial evidence demonstrating reductions in hard clinical cardiovascular events or mortality remains inconclusive.
Limits
No trials evaluated secondary prevention populations. Total trial numbers and sample sizes were small, with follow-ups limited to a maximum of 18 months. Extremely few clinical events occurred, resulting in very wide confidence intervals and low-to-very-low GRADE certainty. Key outcomes including heart failure and revascularisation procedures were entirely unmeasured across comparisons, and studies carried high risks of performance bias.
Cited by
- supports The DASH diet was originally developed by the National Institutes of Health (NIH).