Does fish oil lower blood pressure?

Yes, by a small amount. A 2022 dose-response meta-analysis of 71 randomized trials in 4,973 adults found that 2 to 3 g a day of EPA plus DHA, the two omega-3 fats in fish oil, lowered systolic blood pressure by 2.61 mm Hg and diastolic by 1.64 to 1.80 mm Hg. People with untreated high blood pressure saw more, and people with normal blood pressure saw less.

Established. Two large meta-analyses of randomized trials agree on the direction and that the fall is small. Across 70 trials against placebo, EPA plus DHA lowered systolic pressure by 1.52 mm Hg (95% CI 0.79 to 2.25) and diastolic by 0.99 mm Hg (95% CI 0.44 to 1.54). That is real and modest.

What the trials found

Who gets the most out of it

In the 70-trial analysis, the largest falls were in people with high blood pressure who were not on treatment: systolic down 4.51 mm Hg (95% CI 2.83 to 6.12) and diastolic down 3.05 mm Hg (95% CI 1.74 to 4.35). People with normal blood pressure saw a fall too, of 1.25 mm Hg systolic (95% CI 0.46 to 2.05) and 0.62 mm Hg diastolic, with an interval that only just stays clear of zero (0.02 to 1.22). The 2022 analysis found the same pattern when it split trials by a systolic pressure of 140 or more.

The trials were short. In the 70-trial analysis the average trial lasted 69 days at an average dose of 3.8 g a day, and the placebo was mostly olive oil. In the 2022 analysis most trials did not recruit people with hypertension.

More is not better

The 2022 analysis found the best results between 2 and 3 g a day of EPA plus DHA combined. At 3 g the systolic fall was 2.61 mm Hg (95% CI 1.69 to 3.52) and the diastolic 1.80 mm Hg (95% CI 1.23 to 2.38). Above 3 g a day, the average change was weaker or absent. The doses in these trials are grams of EPA plus DHA combined, so the label line that matters is the EPA and DHA content.

EPA and DHA separately

A meta-analysis of 20 randomized trials found EPA on its own lowered systolic pressure by 2.6 mm Hg (95% CI 0.5 to 4.6), and by 3.8 mm Hg in people with high blood lipids. DHA on its own lowered diastolic pressure by 3.1 mm Hg (95% CI 0.2 to 5.9) in people with high blood lipids. These come from few trials of each fat alone, so they do not settle which one matters more.

Two single trials that show the limits

In a triple-blind trial in 64 people with hypertension, 3 weeks of compound fish oil capsules, which also contained resveratrol, astaxanthin and coenzyme Q10, did not change blood pressure compared with corn oil. Three weeks is short, and the capsules were a mixture, so this is weak evidence against a benefit. In a 6-month double-blind trial in 161 healthy adults with normal blood pressure, eating at least three portions a week of omega-3 enriched chicken and three enriched eggs lowered diastolic pressure by 3.1 mm Hg (98.75% CI 0.3 to 5.8). Blood pressure was a secondary outcome there, and the food came from algae-fed chickens rather than from fish oil capsules.

Unsettled. No trial we found shows that the blood pressure fall from fish oil prevents strokes or heart attacks. The fall is measured. What it does to events has not been tested with blood pressure as the reason.

Who should be careful

Atrial fibrillation, an irregular heart rhythm, is the clearest harm. Across 7 large cardiovascular trials in 81,210 people, mean age 65, followed for about 4.9 years, marine omega-3 supplements raised the risk of atrial fibrillation by 25% (HR 1.25, 95% CI 1.07 to 1.46). There were 2905 cases in all, and the passage we have does not split them by group, so we cannot give the absolute difference. In trials testing more than 1 g a day, the risk was 49% higher (HR 1.49, 95% CI 1.04 to 2.15). The doses that lowered blood pressure in the trials above, 2 to 3 g a day, sit in that higher band.

The European Food Safety Authority found that supplemental EPA plus DHA up to 5 g a day raises no safety concerns for adults, and it set no upper limit. That is a ceiling for general safety in adults. It does not cancel the heart rhythm signal above, and the doses that lowered blood pressure most were 2 to 3 g.

If you already take an ACE inhibitor for blood pressure, the evidence for adding fish oil is thin. A 2012 review for the US Agency for Healthcare Research and Quality pooled 2 trials that added 3 to 5 g a day of omega-3 to an ACE inhibitor and found no extra fall in systolic or diastolic pressure. We have no card on fish oil with other blood pressure drugs, with blood thinners, in pregnancy or in children. That is a gap in what we found, and it does not mean these groups are safe.

Not for everyone. If you have atrial fibrillation, or take a blood thinner or blood pressure medicine, a 2 to 3 g daily dose of fish oil is a decision to make with whoever treats you. It is not a replacement for treatment that is already working.

What expert bodies say

The two main regulators read the same evidence differently. In 2019 the US Food and Drug Administration allowed foods and supplements with at least 0.8 g of EPA and DHA per serving to say that EPA and DHA may help lower blood pressure, only together with its conclusion that the evidence is inconsistent and inconclusive. The European Union authorizes a firmer claim, that DHA and EPA contribute to the maintenance of normal blood pressure. The EU wording is about keeping normal pressure normal and does not mention treating hypertension.

How we searched

What would change this answer

• A large, long randomized trial with blood pressure as its main outcome. Most trials so far lasted weeks and recruited people with normal blood pressure.
• Trials of fish oil added to blood pressure medicines. Two small trials with ACE inhibitors are all we found.
• More trials of EPA and DHA given separately, to settle which one does the work.
• A trial linking the blood pressure fall from fish oil to fewer strokes or heart attacks. Our registry search found no such trial running.

Sources

1. ev-fobp-01 · Meta-analysis or systematic review · dose-response meta-analysis of randomized controlled trials · n = 4973
   The optimal intake in both systolic BP and diastolic BP reductions (mm Hg) were obtained by moderate doses between 2 g/d (systolic BP, -2.61 [95% CI, -3.57 to -1.65]; diastolic BP, -1.64 [95% CI, -2.29 to -0.99]) and 3 g/d (systolic BP, -2.61 [95% CI, -3.52 to -1.69]; diastolic BP, -1.80 [95% CI, -2.38 to -1.23]).
   
   Who: adults 18 and over in 71 randomized controlled trials of DHA, EPA or both, median combined dose 2.8 g/day
   Effect: 2 g/day SBP -2.61 mm Hg (95% CI -3.57 to -1.65), DBP -1.64 (-2.29 to -0.99); 3 g/day SBP -2.61 (-3.52 to -1.69), DBP -1.80 (-2.38 to -1.23)
   Certainty: Main answer. The curve is J-shaped; 79% of trials without hypertension, the average duration is short. Full text in PMC (PMC9238708).
   J Am Heart Assoc, 2022 · checked 2026-10-07 · we read the abstract
2. ev-fobp-02 · Meta-analysis or systematic review · dose-response meta-analysis of randomized controlled trials · n = 71 trials
   In both SBP and DBP models, combined doses >3 g/d were associated with weaker or null changes in BP (Table).
   
   Who: adults in 71 randomized controlled trials; doses 0.2 to 15 g/day
   Effect: doses >3 g/day associated with weaker or null BP changes in both SBP and DBP models
   Certainty: Average across all; in high-risk groups (hypertension, hyperlipidemia) the association is almost linear (see ev-fobp-03).
   J Am Heart Assoc, 2022 · checked 2026-10-07 · we read the fulltext
3. ev-fobp-03 · Meta-analysis or systematic review · dose-response meta-analysis of randomized controlled trials, subgroup analysis · n = 71 trials
   Similar findings were also seen when stratified by hypertension status (SBP ≥140 mm Hg, as defined in most included trials), where patients with hypertension showed greater reductions in SBP and DBP, compared with those without hypertension (Table, Figure S3).
   
   Who: subgroups by hypertension status (SBP >= 140 mm Hg) in 71 randomized controlled trials
   Effect: greater SBP and DBP reductions in hypertension than without hypertension
   Certainty: Subgroups; exact numbers are in the article's table.
   J Am Heart Assoc, 2022 · checked 2026-10-07 · we read the fulltext
4. ev-fobp-04 · Meta-analysis or systematic review · systematic review and meta-analysis of randomized controlled trials · n = 70 trials
   Compared with placebo, EPA+DHA provision reduced systolic blood pressure (-1.52 mm Hg; 95% confidence interval (CI) = -2.25 to -0.79) and diastolic blood pressure (-0.99 mm Hg; 95% CI = -1.54 to -0.44) in the meta-analyses of all studies combined.
   
   Who: 70 randomized controlled trials of EPA+DHA from supplements or food, mean dose 3.8 g/day, mean 69 days
   Effect: SBP -1.52 mm Hg (95% CI -2.25 to -0.79); DBP -0.99 mm Hg (-1.54 to -0.44)
   Certainty: The placebo was mostly olive oil. Full text in PMC (PMC4054797).
   Am J Hypertens, 2014 · checked 2026-10-07 · we read the abstract
5. ev-fobp-05 · Meta-analysis or systematic review · systematic review and meta-analysis of randomized controlled trials, subgroup analysis · n = 70 trials
   The strongest effects of EPA+DHA were observed among untreated hypertensive subjects (systolic blood pressure = -4.51 mm Hg, 95% CI = -6.12 to -2.83; diastolic blood pressure = -3.05 mm Hg, 95% CI = -4.35 to - 1.74), although blood pressure also was lowered among normotensive subjects (systolic blood pressure = -1.25 mm Hg, 95% CI = -2.05 to -0.46; diastolic blood pressure = -0.62 mm Hg, 95% CI = -1.22 to -0.02).
   
   Who: untreated hypertensive and normotensive subjects in randomized controlled trials of EPA+DHA
   Effect: untreated hypertensive SBP -4.51 (95% CI -6.12 to -2.83), DBP -3.05 (-4.35 to -1.74); normotensive SBP -1.25 (-2.05 to -0.46), DBP -0.62 (-1.22 to -0.02)
   Certainty: Untreated hypertension; for people on medication see ev-fobp-10.
   Am J Hypertens, 2014 · checked 2026-10-07 · we read the abstract
6. ev-fobp-06 · Meta-analysis or systematic review · meta-analysis of randomized controlled trials · n = 20 trials
   The summary estimate showed that EPA intervention significantly reduced systolic blood pressure (SBP) (-2.6 mmHg; 95%confident interval (CI): -4.6, -0.5 mmHg), especially in subjects with dyslipidemia (-3.8 mmHg; 95%CI: -6.7, -0.8 mmHg). The pooled effect indicated that supplemental DHA exerted a significant reduction in diastolic blood pressure (DBP) in subjects with dyslipidemia (-3.1 mmHg; 95%CI: -5.9, -0.2 mmHg).
   
   Who: 20 randomized controlled trials of EPA or DHA supplementation
   Effect: EPA SBP WMD -2.6 mm Hg (95% CI -4.6 to -0.5); dyslipidemia SBP -3.8; DHA DBP -3.1 (-5.9 to -0.2) in dyslipidemia
   Certainty: Few studies of individual acids; no full text in PMC (no_pmc).
   Crit Rev Food Sci Nutr, 2019 · checked 2026-10-07 · we read the abstract
7. ev-fobp-07 · Randomized controlled trial(s) · triple-blind randomized placebo-controlled pilot trial · n = 64
   No significant differences were observed in blood pressure, brain and skin microcirculation parameters among the different groups.
   
   Who: 64 hypertensive patients, 32 per group, compound fish oil (omega-3 with resveratrol, astaxanthin, CoQ10) vs corn oil, 2 capsules a day, 3 weeks
   Effect: no significant difference in blood pressure; coronary diastolic flow velocity rose (EDV +1.95, PDV +2.95)
   Certainty: Pilot, 3 weeks, a blend with other substances. The short duration explains the null result on blood pressure.
   Food Funct, 2026 · checked 2026-10-07 · we read the abstract
8. ev-fobp-08 · Randomized controlled trial(s) · double-blinded randomized controlled trial · n = 161
   Furthermore, eating the enriched foods resulted in clinically relevant reductions in diastolic blood pressure (- 3.1 mmHg [- 5.8, - 0.3]).
   
   Who: 161 healthy normotensive adults, at least three portions a week of omega-3 enriched (algae-fed) chicken meat and three enriched eggs, 6 months
   Effect: diastolic BP -3.1 mm Hg (98.75% CI -5.8 to -0.3); omega-3 index +1.7%
   Certainty: Food source, not fish oil capsules; the primary endpoint is the omega-3 index, blood pressure is secondary.
   Sci Rep, 2020 · checked 2026-10-07 · we read the abstract
9. ev-fobp-09 · Meta-analysis or systematic review · systematic review and meta-analysis of randomized controlled trials · n = 81210
   In analyses stratified by dose, the HR was greater in the trials testing >1 g/d (HR, 1.49 [95% CI, 1.04-2.15]; P=0.042) compared with those testing ≤1 g/d (HR, 1.12 [95% CI, 1.03-1.22]; P=0.024; P for interaction <0.001).
   
   Who: 81,210 participants of 7 cardiovascular outcome RCTs, mean age 65, follow-up 4.9 years
   Effect: AF HR 1.25 (95% CI 1.07 to 1.46); >1 g/day HR 1.49 (1.04 to 2.15); per 1 g/day HR 1.11
   Certainty: Blood pressure is lowered by doses of 2-3 g, and the risk of AF rises with dose; people with AF or on anticoagulants: caution. Same paper as fshoil-r6-04.
   Circulation, 2021 · checked 2026-10-07 · we read the abstract
10. ev-fobp-10 · Position of an expert body · agency systematic review (AHRQ comparative effectiveness review) · n = 2 trials
    The pooled analysis of these trials77,152 indicated that there was no difference in either systolic (Figure 13) or diastolic (Figure 14) blood pressure between the intervention and control groups.
    
    Who: adults taking ACE inhibitors in 2 parallel-arm trials, omega-3 3 to 5 g/day, 6 to 25 weeks
    Effect: SBP difference 0 and -1.00 mm Hg; DBP -1.40 and -2.00 mm Hg; pooled no difference
    Certainty: Few data; AHRQ is T2, numbers from the primary RCTs it cites. No interactions that lower blood pressure excessively were found here.
    Agency for Healthcare Research and Quality (US), 2012, Dietary Supplements in Adults Taking Cardiovascular Drugs (Comparative Effectiveness Review No. 51) · checked 2026-10-07 · we read the section
11. ev-fobp-11 · Position of an expert body · regulatory qualified health claim · n = —
    Consuming EPA and DHA combined may help lower blood pressure in the general population and reduce the risk of hypertension. However, FDA has concluded that the evidence is inconsistent and inconclusive.
    
    Who: US foods and dietary supplements with at least 0.8 g EPA and DHA per serving
    Effect: qualified health claim under enforcement discretion; evidence 'inconsistent and inconclusive'
    Certainty: Discrepancy between authorities: the EU allows the claim without a caveat (ev-fobp-12).
    US FDA, 2019, FDA Announces New Qualified Health Claims for EPA and DHA Omega-3 Consumption and the Risk of Hypertension and Coronary Heart Disease (constituent update, June 19, 2019) · checked 2026-10-07 · we read the section
12. ev-fobp-12 · Position of an expert body · EU register of nutrition and health claims · n = —
    POL-HC-8354 Docosahexaenoic acid and Eicosapentaenoic acid (DHA/EPA) DHA and EPA contribute to the maintenance of normal blood pressure Authorised
    
    Who: European Union food labeling
    Effect: authorized health claim (EU register POL-HC-8354)
    Certainty: The condition of use (3 g EPA+DHA per day) is not reflected in the register snapshot; under Regulation 432/2012 it is so. Not checked by machine, so not put into the claim.
    EU Register on nutrition and health claims, claim POL-HC-8354, snapshot 2026-09-21 · checked 2026-10-07 · we read the section
13. fshoil-r6-04 · Meta-analysis or systematic review · systematic review and meta-analysis of RCTs · n = 81210
    Among the 81 210 patients from 7 trials, 58 939 (72.6%) were enrolled in trials testing ≤1 g/d and 22 271 (27.4%) in trials testing >1 g/d of ɷ-3 fatty acids. ... In meta-analysis, the use of marine ɷ-3 fatty acid supplements was associated with an increased risk of AF (n=2905; HR, 1.25 [95% CI, 1.07-1.46]; P=0.013). In analyses stratified by dose, the HR was greater in the trials testing >1 g/d (HR, 1.49 [95% CI, 1.04-2.15]; P=0.042)
    
    Who: 7 RCTs, 81,210 patients, mean age 65, weighted follow-up 4.9 years
    Effect: AF HR 1.25 (1.07 to 1.46); >1 g/d HR 1.49 (1.04 to 2.15); per extra 1 g HR 1.11 (1.06 to 1.15)
    Certainty: AF often recorded as adverse event, not prespecified
    Circulation, 2021 · checked 2026-10-03 · we read the abstract
14. ev-fotg-16 · Position of an expert body · agency scientific opinion (news summary) · n = —
    It concludes that supplemental intakes of EPA and DHA combined at doses up to 5g a day do not raise safety concerns for adults.
    
    Who: adults in the EU
    Effect: EPA+DHA up to 5 g/day supplemental: no safety concern; data insufficient to set a UL
    Certainty: Triglyceride-lowering doses (2-4 g/d) sit below this level; EU intakes are generally far below 5 g/d.
    EFSA, 2012, news: EFSA assesses safety of long-chain omega-3 fatty acids (Scientific Opinion EFSA Journal 2012;10(7):2815) · checked 2026-10-07 · we read the section