Does flaxseed lower cholesterol?

Yes, a little, and it depends on the form. A 2020 meta-analysis of 62 randomized trials in 3,772 people found flaxseed lowered LDL cholesterol by 4.2 mg/dL, with a confidence interval from 1.2 to 7.3 mg/dL. That pool mixed ground seed, oil and lignan capsules, and the oil on its own does not lower LDL. In people who already had high cholesterol or a related disease, a 2021 review of 26 trials found a drop of 6.9 mg/dL. In people with diabetes or coronary artery disease the reviews found no significant change.

Established. Flaxseed lowers LDL cholesterol by a small amount. A 2021 umbrella review of 108 systematic reviews rated this with high certainty by GRADE, and rated the size as small, below 0.20 mmol/L. Oats, barley, psyllium and plant sterols each did more, at 0.20 to 0.40 mmol/L.

What the trials found

The 2020 review also found total cholesterol down 5.4 mg/dL and triglycerides down 9.4 mg/dL, with no change in HDL. Its abstract does not report how much the trials disagreed with each other.

The form matters more than anything else in this literature. A 2009 meta-analysis of 28 trials split the products apart. Whole flaxseed lowered LDL by 0.16 mmol/L, about 6 mg/dL, and lignan supplements by the same amount, while flaxseed oil had no significant effect. Across all products together the LDL drop was 3.1 mg/dL (0.08 mmol/L), with an interval that reached zero. The effect was larger in women, especially after menopause, and in people who started with high cholesterol. The 2021 review in 1,559 people with lipid disorders found the same split, with whole seed and lignans significant and oil not. Its trials disagreed a great deal, with heterogeneity of 90.6%, which the authors traced to lipid status and product type.

Myth. Flaxseed oil lowers LDL cholesterol the way the seed does. Two meta-analyses that separated oil from seed found no significant effect from the oil. A 2023 meta-analysis of 19 trials in 1,183 overweight adults found that alpha-linolenic acid from plants, the main fat in flaxseed oil, slightly raised LDL against placebo while it lowered triglycerides.

A 2024 meta-analysis rated by GRADE found flaxseed lowered apolipoprotein B and lipoprotein(a), with no change in apolipoprotein A-I. It reported standardized differences only, so the size in mg/dL is not known, and its abstract does not give the number of trials.

The effect shows early and fades

Single trials show a pattern the pooled numbers hide. In 62 adults with high LDL on a low-fat diet, 1.4 oz (40 g) of ground flaxseed a day in baked goods lowered LDL by 13% against wheat bran at 5 weeks. At 10 weeks the gap was 7% and no longer significant. In a 12-month double-blind trial in 110 people with peripheral artery disease, 1.1 oz (30 g) of milled flaxseed a day cut LDL by 15% at one month, and by 12 months the difference from placebo was gone.

Two trials in postmenopausal women point the same way as the 2009 subgroup. In 55 Native American women with mild to moderately high cholesterol, about 30 g a day for three months lowered total cholesterol by about 7% and LDL by about 10%. That trial was small and its abstract gives only approximate percentages. In a double-blind trial of 1.4 oz (40 g) of ground flaxseed a day for three months, total and non-HDL cholesterol fell 6%, while the 4.7% fall in LDL did not reach significance. That abstract does not say how many women took part.

Where it did not show

In people with diabetes, a 2025 meta-analysis of 16 trials in 1,136 participants found no effect on total or LDL cholesterol, though triglycerides fell. Heterogeneity was above 90% for the cholesterol results. In coronary artery disease, a 2024 meta-analysis of 6 randomized trials found no significant change in LDL, HDL or total cholesterol. Those trials were few and small and many patients were likely on statins. A 12-week trial of 30 g a day in 50 patients with coronary artery disease, against usual care, also found no change in blood lipids.

Who should be careful

Not for everyone. Children are the clearest caution. In a 4-week blinded trial of 32 children aged 8 to 18 with high cholesterol, 1.1 oz (30 g) of ground flaxseed a day in muffins and bread lowered HDL by 15% and raised triglycerides by 26%. The fall in LDL, 6.96 mg/dL, did not reach significance. The authors called these adverse changes in the lipid profile, while noting that an LDL benefit could not be excluded.

The US National Center for Complementary and Integrative Health advises against eating raw or unripe flaxseeds, because they may contain potentially toxic compounds. The page does not name them. The compounds in linseed that release cyanide are cyanogenic glycosides, and the European Food Safety Authority set an acute reference dose of 20 micrograms of cyanide per kg of body weight that applies whatever food the cyanide comes from.

The same agency says there are theoretical reasons flaxseed might interact with anticoagulant or antiplatelet drugs, and it cites no clinical cases. If you take a blood thinner, mention flaxseed to the person who prescribes it. It also says some studies suggest flaxseed is possibly unsafe in pregnancy, while calling that evidence not conclusive.

We have no card on flaxseed together with statins, and the trials above do not let us say whether the seed adds anything to a statin.

What expert bodies say

The European Union authorizes the label claim that alpha-linolenic acid contributes to the maintenance of normal blood cholesterol levels. The claim is about the fat as a nutrient. It is not a finding about flaxseed, and the trials of flaxseed oil, which is mostly that fat, did not lower LDL. We have no card on any US label claim for flaxseed and cholesterol, and we found no Cochrane review on the question.

The NCCIH and EFSA positions above concern safety. Neither agency rates flaxseed as a treatment for cholesterol in the cards we hold.

How we searched

What would change this answer

• A trial with heart attacks and strokes as outcomes. Every result here is a blood marker, and we found no such trial.
• Trials longer than a year. The two trials that measured LDL over time saw the effect fade, by 10 weeks in one and by 12 months in the other.
• The registered trial NCT06911060 on flaxseed and total, LDL and HDL cholesterol, which had not yet started recruiting when we searched.
• Trials in people already taking statins, to show whether the seed adds anything to the drug.

Nutrition facts and more on the seed itself are on the flaxseed page.

Sources

1. ev-flch-01 · Meta-analysis or systematic review · systematic review and dose-response random-effects meta-analysis of RCTs · n = 3772
   Our analysis showed that flaxseed supplementation significantly reduced total cholesterol (TC) (WMD = -5.389 mg/dL; 95% CI: -9.483, -1.295, p = 0.010), triglyceride (TG) (WMD = -9.422 mg/dL; 95% CI: -15.514, -3.330, p = 0.002), and low-density lipoprotein cholesterol (LDL-C) (WMD = -4.206 mg/dl; 95% CI: -7.260, -1.151, p = 0.007) concentrations.
   
   Who: participants of 62 RCTs of flaxseed supplementation (whole, oil or lignan), searched to May 2019
   Effect: LDL-C WMD -4.206 mg/dL (95% CI -7.260 to -1.151); total cholesterol -5.389 mg/dL (-9.483 to -1.295); triglycerides -9.422 mg/dL; HDL-C +0.047 mg/dL (NS)
   Certainty: Pools all flaxseed products, including oil, which on its own does not lower LDL; heterogeneity not reported in the abstract.
   Pharmacol Res, 2020 · checked 2026-10-07 · we read the abstract
2. ev-flch-02 · Meta-analysis or systematic review · meta-analysis of randomized controlled trials · n = 28 studies
   Flaxseed interventions reduced total and LDL cholesterol by 0.10 mmol/L (95% CI: -0.20, 0.00 mmol/L) and 0.08 mmol/L (95% CI: -0.16, 0.00 mmol/L), respectively; significant reductions were observed with whole flaxseed (-0.21 and -0.16 mmol/L, respectively) and lignan (-0.28 and -0.16 mmol/L, respectively) supplements but not with flaxseed oil.
   
   Who: adults in English-language RCTs of flaxseed, flaxseed oil or lignans published 1990 to 2008
   Effect: all products: total cholesterol -3.9 mg/dL (95% CI -7.7 to 0; metric: -0.10 mmol/L, -0.20 to 0.00), LDL -3.1 mg/dL (-6.2 to 0; metric: -0.08 mmol/L, -0.16 to 0.00); whole flaxseed TC -0.21 and LDL -6.2 mg/dL (-0.16 mmol/L); lignan TC -0.28 and LDL -6.2 mg/dL (-0.16 mmol/L); flaxseed oil not significant; larger in women, especially postmenopausal, and with high baseline cholesterol
   Certainty: Jadad-scored; larger effects in higher-quality studies; no HDL or triglyceride change.
   American Journal of Clinical Nutrition, 2009 (Pan et al., Meta-analysis of the effects of flaxseed interventions on blood lipids) · checked 2026-10-07 · we read the abstract
3. ev-flch-03 · Meta-analysis or systematic review · systematic review and dose-response meta-analysis of RCTs · n = 1559
   Meta-analysis suggested significant net change in LDL-C concentrations following supplementation with flaxseed-containing products (WMD = − 6.92 mg/dL, 95% CI − 8.58, − 5.25; I2 = 90.6%), in which whole flaxseed and lignan supplementation had significant lowering-effect on LDL-C concentrations, rather than flaxseed oil intervention (shown in Fig. 1b).
   
   Who: patients with dyslipidemia-related diseases (hyperlipidemia, metabolic syndrome, NAFLD, atherosclerosis) in 31 RCTs; LDL reported in 30 comparisons from 26 studies
   Effect: LDL-C WMD -6.92 mg/dL (95% CI -8.58 to -5.25), I2 90.6%; whole flaxseed and lignans significant, flaxseed oil not; HDL-C -0.45 mg/dL (NS)
   Certainty: Very high heterogeneity, explained by lipid status and product type; abstract reports whole flaxseed LDL -10.51 mg/dL.
   Nutrition & Metabolism, 2021, 18:91 (Comparisons of the effects of different flaxseed products consumption on lipid profiles...) · checked 2026-10-07 · we read the fulltext
4. ev-flch-04 · Meta-analysis or systematic review · systematic review of systematic reviews with GRADE · n = 108 systematic reviews
   Soy protein, tomatoes, flaxseeds, and almonds caused small reductions.
   
   Who: systematic reviews and meta-analyses of RCTs of foods and LDL cholesterol, at least 13 days
   Effect: flaxseeds: small LDL reduction (below 7.7 mg/dL (0.20 mmol/L)) with high certainty by GRADE
   Certainty: High certainty applies to the direction and small size of the effect.
   Nutr Metab Cardiovasc Dis, 2021 · checked 2026-10-07 · we read the abstract
5. ev-flch-05 · Meta-analysis or systematic review · systematic review and meta-analysis of RCTs with GRADE · n = —
   Our results showed that flaxseed supplementation significantly reduced apo-BI (SMD: -0.57; 95 % CI: -0.95, -0.19, p = 0.003; I2 = 83.2 %, heterogeneity p < 0.001) and lipo(a) decreased (SMD: -0.34; 95 % CI: -0.59, -0.09, p=0.007; I2=30.3 %, heterogeneity p=0.197).
   
   Who: adults in randomized clinical trials of flaxseed published to June 2024
   Effect: apoB SMD -0.57 (95% CI -0.95 to -0.19), I2 83.2%; Lp(a) SMD -0.34 (-0.59 to -0.09); apoA-I SMD -0.37 (NS)
   Certainty: Standardized mean differences only, so no size in mg/dL; number of trials not given in the abstract.
   Prostaglandins Other Lipid Mediat, 2024 · checked 2026-10-07 · we read the abstract
6. ev-flch-06 · Meta-analysis or systematic review · GRADE-assessed systematic review and meta-analysis of RCTs · n = 1136
   CONCLUSION: Flaxseed supplementation effectively reduces anthropometric indices and triglyceride levels in individuals with type 2 diabetes but does not suggest any benefit on blood pressure and other lipid profile parameters.
   
   Who: diabetic patients in RCTs of flaxseed supplementation, searched to June 2024
   Effect: total cholesterol SMD -0.43 (95% CI -0.99 to 0.12, NS); LDL-C SMD -0.09 (-0.87 to 0.70, NS); HDL-C NS; triglycerides SMD -0.56 (significant)
   Certainty: Heterogeneity above 90% for cholesterol outcomes.
   Diabetes Metab Syndr, 2025 · checked 2026-10-07 · we read the abstract
7. ev-flch-07 · Meta-analysis or systematic review · systematic review and meta-analysis of RCTs · n = 6 RCTs
   The pooled results did not show significant changes in the WMD of lipid factors (high-density lipoprotein cholesterol, triglycerides (TG), low-density lipoprotein cholesterol, and total cholesterol) following flaxseed intake.
   
   Who: patients with coronary artery disease in 6 RCTs, searched to June 2023
   Effect: no significant change in HDL-C, LDL-C, total cholesterol or triglycerides; triglycerides -18.39 mg/dL only after sensitivity analysis
   Certainty: Few small trials; many patients likely on statins.
   Clin Cardiol, 2024 · checked 2026-10-07 · we read the abstract
8. ev-flch-08 · Meta-analysis or systematic review · systematic review and meta-analysis of RCTs · n = 1183
   Compared with placebo, dietary ALA supplementation significantly reduced C-reactive protein concentration (standardized mean difference [SMD] = -0.38 mg/L; 95% confidence interval [CI]: -0.72, -0.04), tumor necrosis factor-α concentration (SMD = -0.45 pg/mL; 95% CI: -0.73, -0.17), triglyceride in serum (SMD = -4.41 mg/dL; 95% CI: -5.99, -2.82), and systolic blood pressure (SMD = -0.37 mm Hg; 95% CI: -0.66, -0.08); but led to a significant increase in low-density lipoprotein cholesterol concentrations (SMD = 1.32 mg/dL; 95% CI: 0.05, 2.59).
   
   Who: adults with overweight or obesity given vegetable ALA as supplement or food, versus placebo
   Effect: LDL-C SMD +1.32 mg/dL (95% CI 0.05 to 2.59); triglycerides -4.41 mg/dL; total cholesterol and HDL-C unchanged
   Certainty: Concerns isolated ALA, not whole flaxseed; supports that the oil fraction is not what lowers LDL.
   Adv Nutr, 2023 · checked 2026-10-07 · we read the abstract
9. ev-flch-09 · Randomized controlled trial(s) · double-blind randomized placebo-controlled trial, 12 months · n = 110
   Dietary flaxseed in PAD patients resulted in a 15% reduction in circulating LDL cholesterol as early as 1 mo into the trial (P = 0.05).
   
   Who: patients with peripheral artery disease; 30 g/day milled flaxseed in foods (n = 58) vs 30 g whole wheat (n = 52)
   Effect: LDL-C -15% at 1 month (P = 0.05); no significant difference at 6 (P = 0.12) or 12 months (P = 0.33)
   Certainty: FlaxPAD, NCT00781950; effect on LDL with or without statins not established here.
   J Nutr, 2015 · checked 2026-10-07 · we read the abstract
10. ev-flch-10 · Randomized controlled trial(s) · randomized controlled trial with matched wheat bran control · n = 62
    Compared to wheat, flaxseed significantly reduced LDL-C at 5 weeks (-13%, p < 0.005), but not at 10 weeks (-7%, p = 0.07).
    
    Who: men and post-menopausal women with LDL-C 130 to 200 mg/dl on a low-fat diet; ground flaxseed baked products vs wheat bran
    Effect: LDL-C -13% at 5 weeks (p < 0.005), -7% at 10 weeks (p = 0.07); Lp(a) -14%; HDL-C in men -16% at 5 weeks and -9% at 10 weeks
    Certainty: Short-lived effect; HDL fall in men warrants caution.
    J Am Coll Nutr, 2008 · checked 2026-10-07 · we read the abstract
11. ev-flch-11 · Randomized controlled trial(s) · placebo-controlled blinded randomized clinical trial, 4 weeks · n = 32
    The use of dietary flaxseed supplementation, while safe, was associated with adverse changes in the lipid profile of children with hypercholesterolemia, although a potential benefit of low-density lipoprotein cholesterol lowering could not be excluded.
    
    Who: children aged 8 to 18 with LDL-C 135 to under 193 mg/dL; muffins and bread with ground flaxseed vs whole-wheat flour
    Effect: HDL-C -7.35 mg/dL (-15%); triglycerides +29.23 mg/dL (+26%); LDL-C -6.96 mg/dL (95% CI -16.63 to 2.71, NS); no safety concerns
    Certainty: Small and short; NCT01007344; authors conclude flaxseed may not be a viable option for children.
    JAMA Pediatr, 2013 · checked 2026-10-07 · we read the abstract
12. ev-flch-12 · Randomized controlled trial(s) · randomized controlled trial, three arms, 3 months · n = 55
    Dietary flaxseed supplementation lowered total cholesterol and low-density lipoprotein cholesterol (LDL-C) by approximately 7% and 10%, respectively.
    
    Who: mild to moderately hypercholesterolemic Native American postmenopausal women; control, flaxseed, or flaxseed plus oat bran
    Effect: total cholesterol about -7%, LDL-C about -10%; HDL and triglycerides unchanged
    Certainty: Small; abstract gives approximate percentages only.
    J Womens Health (Larchmt), 2008 · checked 2026-10-07 · we read the abstract
13. ev-flch-13 · Randomized controlled trial(s) · double-blind randomized controlled trial, 3 months · n = —
    Flaxseed supplementation lowered (P < 0.05) both serum total cholesterol and non-high-density lipoprotein cholesterol by 6%, whereas the comparative control regimen had no such effect.
    
    Who: postmenopausal women not on hormone replacement therapy; 40 g ground flaxseed vs wheat-based control, plus calcium and vitamin D
    Effect: total cholesterol and non-HDL-C -6% (P < 0.05); LDL-C and HDL-C -4.7% (NS); apoB -7.5%, apoA-1 -6%
    Certainty: Sample size not stated in the abstract.
    J Clin Endocrinol Metab, 2002 · checked 2026-10-07 · we read the abstract
14. ev-flch-14 · Randomized controlled trial(s) · randomized controlled parallel trial, 12 weeks · n = 50
    After 12 weeks of intervention, no significant changes were observed in plasma lipids and fecal microbial composition in the two study groups.
    
    Who: patients with coronary artery disease; flaxseed 30 g/day vs usual care
    Effect: no significant change in plasma lipids; Lp-PLA2 activity improved
    Certainty: Open usual-care control; small.
    Nutr Health, 2026 · checked 2026-10-07 · we read the abstract
15. ev-flch-15 · Position of an expert body · agency consumer fact sheet · n = —
    Don't eat raw or unripe flaxseeds; they may contain potentially toxic compounds.
    
    Who: people eating flaxseed
    Effect: avoid raw or unripe seeds
    Certainty: Compounds not named on the page; cyanogenic glycosides per EFSA.
    NIH National Center for Complementary and Integrative Health, Flaxseed and Flaxseed Oil (updated February 2025) · checked 2026-10-07 · we read the section
16. ev-flch-16 · Position of an expert body · agency consumer fact sheet · n = —
    There are theoretical reasons to suspect that flaxseed or flaxseed oil might interact with other drugs, such as anticoagulant or antiplatelet drugs.
    
    Who: people taking anticoagulant or antiplatelet drugs
    Effect: theoretical interaction
    Certainty: Theoretical; no clinical cases cited.
    NIH National Center for Complementary and Integrative Health, Flaxseed and Flaxseed Oil (updated February 2025) · checked 2026-10-07 · we read the section
17. ev-flch-17 · Position of an expert body · agency consumer fact sheet · n = —
    Some studies of the use of flaxseed during pregnancy suggest it is possibly unsafe, but the evidence is not conclusive.
    
    Who: pregnant women
    Effect: possibly unsafe in pregnancy
    Certainty: Underlying studies not named on the page.
    NIH National Center for Complementary and Integrative Health, Flaxseed and Flaxseed Oil (updated February 2025) · checked 2026-10-07 · we read the section
18. ev-flch-18 · Position of an expert body · agency scientific opinion (EFSA CONTAM Panel) · n = —
    In the present opinion, the CONTAM Panel concluded that this ARfD is applicable for acute effects of CN regardless the dietary source.
    
    Who: European consumers of foods containing cyanogenic glycosides
    Effect: ARfD 20 mcg/kg bw for cyanide; mean exposures below ARfD; 95th percentile up to about 2.5-fold above in some child and adolescent surveys; chronic guidance value not derivable
    Certainty: EFSA judges the exceedance unlikely to cause harm given conservative assumptions.
    EFSA CONTAM Panel, Evaluation of the health risks related to the presence of cyanogenic glycosides in foods other than raw apricot kernels, EFSA Journal 2019;17(4):5662 · checked 2026-10-07 · we read the abstract
19. ev-flch-19 · Position of an expert body · EU register entry · n = —
    POL-HC-6327 Alpha-linolenic acid (ALA) ALA contributes to the maintenance of normal blood cholesterol levels Authorised
    
    Who: EU food labels
    Effect: claim authorized for ALA; conditions of use in Regulation (EU) 432/2012, not quoted here
    Certainty: Concerns ALA as a nutrient; trials show flaxseed oil itself does not lower LDL, so the claim does not prove a flaxseed effect.
    EU Register on nutrition and health claims, claim POL-HC-6327, snapshot 2026-09-21 · checked 2026-10-07 · we read the section