Does eating flaxseed lower cholesterol and blood pressure?

Pooled trials find ground flaxseed lowers blood pressure a few points and LDL modestly, with effects growing at higher doses and longer use.

Published October 2026

Short answer

Limited evidence: about 30 g a day of ground flaxseed for 12+ weeks modestly lowers blood pressure and LDL, total cholesterol and triglycerides, with no HDL change. Evidence grade C (Limited). Meta-analyses of dozens of RCTs with consistent direction; downgraded for high heterogeneity with some conflicting subgroup results and because blood pressure and lipids are surrogate markers.

Key takeaways

Across 33 trials with 2,427 people, flaxseed lowered systolic pressure by about 3.2 points and diastolic by about 2.6 points [1].
Across 62 trials with 3,772 people, flaxseed lowered total cholesterol by about 5.4 mg/dL, LDL by about 4.2 mg/dL and triglycerides by about 9.4 mg/dL, with no HDL change [2].
The clearest results came with at least 30 g a day of ground whole seed for 12 to 20 weeks or more, especially in people with hypertension [1].
In diabetic patients, flaxseed lowered triglycerides but did not significantly change blood pressure or other lipids, so benefits are not uniform [3].

The short version

Yes, modestly: pooled trials find ground flaxseed lowers systolic pressure by about 3 points and diastolic by about 2 to 3 points, with bigger drops in people with hypertension [1]. It also lowers total cholesterol by about 5 mg/dL, LDL by about 4 mg/dL and triglycerides by about 9 mg/dL, with no change in HDL, across 62 trials with 3,772 people [2]. Benefits build with around 30 g a day of ground seed for at least 12 weeks [1][4].

What the studies show

The strongest blood pressure evidence is a 2023 dose-response meta-analysis of 33 trials with 2,427 participants [1]. Flaxseed cut systolic pressure by 3.19 mmHg (95% CI -4.15 to -2.24) and diastolic by 2.61 mmHg (95% CI -3.27 to -1.94) [1]. Two earlier reviews agree: 15 trials with 1,302 people found systolic down 2.85 mmHg and diastolic down 2.39 mmHg [5], and 11 studies found systolic down 1.77 mmHg and diastolic down 1.58 mmHg [4]. A 2022 trial in 112 hypertensive patients illustrates the top end: 30 g a day for 12 weeks cut systolic by 13.38 points versus a 1.72-point rise with placebo, and diastolic by 5.6 points versus a 2.39-point rise [6].

For cholesterol, a 2020 meta-analysis of 62 trials with 3,772 participants found total cholesterol down 5.39 mg/dL, triglycerides down 9.42 mg/dL and LDL down 4.21 mg/dL, with HDL essentially unchanged (up 0.05 mg/dL, not significant) [2]. A 2022 review of 14 trials with 1,107 people found the same pattern in dyslipidemic patients: lower total cholesterol, LDL and triglycerides with no HDL change [7]. In 70 ulcerative colitis patients, 30 g a day of ground flaxseed for 12 weeks lowered total cholesterol and triglycerides and raised HDL [8].

The nuances

Dose, form and duration matter: the largest pressure drops came with at least 30 g a day, use beyond 12 to 20 weeks, and whole ground seed rather than oil or lignan extracts [1][4][5]. People with hypertension or overweight saw bigger gains than healthy volunteers [1][7]. Results vary a lot between trials, with heterogeneity above 90% in the largest blood pressure review [1]. Not every group benefits: a 2025 review of 16 trials with 1,136 diabetic patients found lower triglycerides but no significant change in blood pressure, total cholesterol, LDL or HDL [3], and the colitis trial found no blood pressure change [8]. Blood pressure and cholesterol are risk markers, not heart attacks or strokes, so these numbers say nothing direct about prevented disease [1][2].

Flaxseed is generally considered safe in moderate amounts, but its fiber can cause bloating, gas, stomach pain and diarrhea, worse at higher doses [9]. Its ALA may reduce platelet aggregation and interfere with blood clotting when combined with anticoagulant medicines [9]. It contains small amounts of cyanogenic glycosides, generally safe and reduced by processing, and lignans with mild estrogen-like effects, so people with hormone-sensitive conditions, and pregnant or breastfeeding women, are advised to ask a clinician before using large amounts [9][10]. New users are advised to start with 1 to 2 tablespoons a day and increase as tolerated [9].

What this means for you

The trials support ground flaxseed as a small, food-based helper for blood pressure and cholesterol: about 30 g (roughly 3 to 4 tablespoons) of ground seed daily for at least 12 weeks is the pattern linked to the clearest results [1][9]. Whole ground seed beats oil for blood pressure, and grinding matters because it frees up the ALA and lignans [5][10]. It is an add-on to, not a substitute for, prescribed medicines, and anyone on blood thinners or blood pressure drugs should talk to a doctor first [9]. Full detail is on the Flaxseed page.

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Flaxseed — Pooled trials find ground flaxseed modestly lowers blood pressure and LDL, total cholesterol and triglycerides, with the clearest results at around 30 g a day…