Flax and Reduced Systolic Blood Pressure

Research synthesisLow evidenceMixed effect size3 studies · 2 beneficial · 1 neutral · 0 harmful

Across 3 studies, 2 reported beneficial effects of flax on reducing systolic blood pressure, while 1 found a neutral effect. The effect sizes were mixed (small to large), with the largest effect observed in a 49-day trial using 25 mL/day flaxseed oil in patients with metabolic syndrome. The median study duration was 49 days, suggesting effects may be observed after 7 weeks of supplementation.

Effective dose range: 25 mL/day
Studied populations: patients with metabolic syndrome and related disorders

Caveats: Evidence base is small (only 3 studies) — conclusions should be considered preliminary. One meta-analysis found no significant effect on SBP in normotensive and hypertensive adults, while another meta-analysis and an RCT showed significant reductions in patients with metabolic syndrome, indicating the benefit may be population-dependent.

Generated Jun 12, 2026

Doses used in studies

mL/day: 25 (median 25, IQR 25–25) — 1 study

Time to effect

Median: 7 weeks · IQR 7 weeks–7 weeks · Range 7 weeks–7 weeks — Reported in 1 of 3 studies

3 of 3 papers

Supplementation of Olive Oil and Flaxseed Oil on Blood Pressure and Inflammation in Healthy and At-Risk Adults: A Systematic Literature Review and Meta-Analysis.
- 2025-01
- Meta-Analysis · n = 17
- Current hypertension reviews 20(3)
- - Tara B McNabb
  - Ian Young
  - Rachel G Newman
  - Roy C Skinner
  - Vagner A Benedito
  - Janet C Tou
- PubMed: 39558500
- DOI: 10.2174/0115734021337760241104063418
5 Insights on
- Reduced Systolic Blood Pressure
- High evidence
- Clinical
Meta-analysis using a random-effects model reported no significant effect on SBP (n=17 mean difference (MD) -0.48; 95% CI: -1.76, 0.80; p=0.65, I² =0%)
Effect
Neutral
Effect size
Small
Significant
No
The effect of flaxseed oil consumtion on blood pressure among patients with metabolic syndrome and related disorders: A systematic review and meta-analysis of randomized clinical trials.
- 2022-07-20
- Meta-Analysis
- Phytotherapy research : PTR 36(10)
- - Trias Mahmudiono
  - Saade Abdalkareem Jasim
  - Yasir Salam Karim
  - Dmitry Olegovich Bokov
  - Walid Kamal Abdelbasset
  - Kholmurod S Akhmedov
  - Ghulam Yasin
  - Lakshmi Thangavelu
  - Yasser Fakri Mustafa
  - Shehla Shoukat
  - Mazin A A Najm
  - Mohammad Amraei
- PubMed: 35859037
- DOI: 10.1002/ptr.7566
2 Insights on
- Reduced Systolic Blood Pressure
- High evidence
- Clinical
Meta-analysis of five trials (6 arms) showed significant reductions in systolic (WMD: -3.86 mmHg, 95% CI: -7.59 to -0.13, p = .04) BP (SBP) after flaxseed oil consumption.
Effect
Beneficial
Effect size
Small
Significant
Yes
Comparison of the effects of flaxseed oil and sunflower seed oil consumption on serum glucose, lipid profile, blood pressure, and lipid peroxidation in patients with metabolic syndrome.
- 2018-01
- RCT · n = 60
- Journal of clinical lipidology 12(1)
- - Atefeh Akrami
  - Farzad Nikaein
  - Siavash Babajafari
  - Shiva Faghih
  - Hassan Yarmohammadi
- PubMed: 29229363
- DOI: 10.1016/j.jacl.2017.11.004
9 Insights on
- Reduced Systolic Blood Pressure
- High evidence
- Clinical
between-group changes were significant (<0.05) for systolic BP (mean [±standard deviation {SD}] changes were -14.0 ± 22.41 in the FO group [P = .004] and 0.92 ± 8.70 in the SO group [P = .594])
Effect
Beneficial
Effect size
Large
Significant
Yes
Dose
25 mL/day

Flax and Reduced Systolic Blood Pressure

Supplementation of Olive Oil and Flaxseed Oil on Blood Pressure and Inflammation in Healthy and At-Risk Adults: A Systematic Literature Review and Meta-Analysis.

The effect of flaxseed oil consumtion on blood pressure among patients with metabolic syndrome and related disorders: A systematic review and meta-analysis of randomized clinical trials.

Comparison of the effects of flaxseed oil and sunflower seed oil consumption on serum glucose, lipid profile, blood pressure, and lipid peroxidation in patients with metabolic syndrome.