Research synthesisModerate evidenceMixed effect size4 studies · 3 beneficial · 1 neutral · 0 harmful
Across 4 studies (3 beneficial, 1 neutral), flaxseed supplementation shows moderate evidence for a small-to-moderate reduction in diastolic blood pressure, primarily in clinical populations with type 2 diabetes, metabolic diseases, or hypertension. Three of four studies reported statistically significant reductions, with effect sizes ranging from small to moderate (e.g., weighted mean differences of -2.50 to -4.87 mmHg). No consistent dose or form was reported across studies.
- Studied populations: clinical populations with type 2 diabetes, metabolic diseases, cardiovascular risk factors, or hypertension
Caveats: Available evidence is overwhelmingly positive — 3 of 4 studies are beneficial and statistically significant — but publication bias is a concern (null-result studies are less likely to be published or indexed). The evidence base is also small (only 4 studies), so conclusions should be considered preliminary. Dose and form data were not consistently reported, limiting practical guidance. The neutral finding from the highest-quality study (evidence score 7, meta-analysis in type 2 diabetes) did not reach statistical significance (p = 0.060), suggesting the effect may be less robust in certain populations or when higher-quality evidence is considered.
Generated Jun 10, 2026