Biohacking Kompakt

Supplement

Omega-3 (EPA/DHA)

Fatty acid · fish oil / algae oil

Omega-3 fatty acids (EPA and DHA) are among the most thoroughly studied dietary supplements of all. Three large randomized trials missed their primary endpoint, and in 2019 the EMA removed the indication for secondary prevention after a heart attack.

What omega-3 is

EPA and DHA are long-chain polyunsaturated fatty acids from fatty fish and algae oil. EPA tends to have an anti-inflammatory effect, while DHA is a building block of the brain and nerve tissue. Lowering triglycerides is the most clearly established effect.

The omega-3 index in the blood serves as a status marker. The quality of the oils matters, because low-quality products can oxidize; the TOTOX value is commonly stated.

Why the evidence is considered mixed

Large randomized trials with hard endpoints exist - but their results partly contradict each other, and the studies reviewed here were negative. Much more is claimed in marketing than the studies support.

The key is to distinguish between the prespecified primary endpoint and the many secondary analyses. If the primary endpoint is missed, individual positive secondary findings are indications, not proof.

What is well supported

  • Hardly any dietary supplement has been tested as thoroughly. There are three large placebo-controlled trials with hard endpoints alone: VITAL with 25,871 participants over a median of 5.3 years, ASCEND with 15,480 people with diabetes over 7.4 years and STRENGTH with 13,078 high-risk patients at 675 centers in 22 countries.
  • The heart attack finding in VITAL was significant. As a secondary result, total heart attacks came in at HR 0.72 (95% CI 0.59-0.90); the confidence interval does not include 1. Because the primary endpoint was missed, this is an indication, not proof - but it is a result that deserves to be mentioned.
  • Still approved as a medicine for lowering triglycerides. On 2019-03-29 the EMA removed the indication for secondary prevention after a heart attack; the approval for lowering triglycerides explicitly remained in place.
  • The safety data are exceptionally broad. The meta-analysis by Abuknesha 2026 covers 35 randomized trials with 114,592 participants aged 50 and over, each lasting at least twelve months and using at least 500 mg of EPA plus DHA daily. An increased risk of atrial fibrillation was found only in people at high cardiovascular risk combined with more than 1,500 mg daily; in the other groups, the odds ratios were 1.07, 1.06 and 1.03.

What the studies show

VITAL: primary endpoint missed

Manson 2019 randomized 25,871 people (men aged 50 and over, women aged 55 and over) from the US general population, without preselection for risk, to 1 g of marine n-3 daily or placebo; median follow-up 5.3 years. Major cardiovascular events occurred 386 versus 419 times, HR 0.92 (95% CI 0.80-1.06; p=0.24) - not significant. Invasive cancers: 820 versus 797, HR 1.03 (0.93-1.13; p=0.56). As secondary results, total heart attacks came in at HR 0.72 (0.59-0.90), stroke at HR 1.04 (0.83-1.31), cardiovascular death at HR 0.96 (0.76-1.21).

STRENGTH: stopped early

Nicholls 2020 studied 13,078 statin-treated high-risk patients with elevated triglycerides and low HDL cholesterol (mean age 62.5 years, 70 percent with diabetes) at 675 centers in 22 countries, with 4 g of omega-3 carboxylic acid daily against corn oil. The trial was stopped at 1,384 of a planned 1,600 events because a benefit had become unlikely. The primary endpoint occurred in 785 (12.0 percent) versus 795 (12.2 percent), HR 0.99 (0.90-1.09; p=0.84).

ASCEND: no effect in people with diabetes

ASCEND studied 15,480 people with diabetes and no known cardiovascular disease, with 1 g of n-3 daily against olive oil over 7.4 years, at an adherence of 76 percent. Serious vascular events occurred in 689 people (8.9 percent) versus 712 (9.2 percent), rate ratio 0.97 (95% CI 0.87-1.08; p=0.55). All-cause mortality was 752 (9.7 percent) versus 788 (10.2 percent), RR 0.95 (0.86-1.05).

Atrial fibrillation: a signal only at high dose and high risk

Abuknesha 2026 pooled 35 randomized trials with 37 data sets and 114,592 participants aged 50 and over (at least 500 mg of EPA plus DHA daily, at least 12 months). Only in the group at high cardiovascular risk and on a high dose above 1,500 mg daily was new-onset atrial fibrillation increased: OR 1.43 (95% CI 1.14-1.79), an absolute increase of 0.8 percentage points (0.40-1.1). The other groups were not significant (OR 1.07, 1.06 and 1.03).

Where the data stop

  • That 1 g of omega-3 daily prevents heart attacks. The finding from VITAL is a secondary result with a missed primary endpoint. As isolated proof, it is not robust.
  • That omega-3 protects against further events after a heart attack. The EMA removed this indication in 2019 after the medicines had proven not effective for it.
  • That common supplement doses of around 1 g daily trigger atrial fibrillation. The signal in the meta-analysis concerned only high-risk patients taking more than 1,500 mg daily; the other groups were not significant.

Status, approval and legal situation

On 2019-03-29 the EMA confirmed that medicines containing omega-3 acid ethyl esters (EPA plus DHA, 1 g daily) are not effective for secondary prevention after a heart attack; this indication was removed. The approval for lowering triglycerides remains in place. Over-the-counter dietary supplements are not directly affected by this decision, but marketing them with claims of heart protection contradicts it.

Safety

In STRENGTH, gastrointestinal side effects occurred in 24.7 percent versus 14.7 percent, meaning about ten percentage points more often at high dose. The atrial fibrillation signal was limited to high-risk patients taking more than 1,500 mg daily. Low-quality oils can oxidize; if you take blood thinners or before surgery, consult a physician.

BK-Score Well supported

Human evidence8
Mechanism8
Safety data9
Hype gap6
Track record of use10

Large randomized trials (including VITAL, REDUCE-IT, STRENGTH) with hard endpoints exist – but their results partly contradict each other. Mechanism and safety are well studied; much more is claimed in marketing than the studies support.

The score rates the state of knowledge, not the substance. “Safety data 9” means well studied – not harmless. “Track record of use 9” means used long and widely – that is not proof of efficacy.
Subjective assessment by Biohacking Kompakt based on published scoring rules – not a scientific rating and not a medical recommendation. Rules and all ratings (German)

Frequently asked questions about omega-3 (EPA/DHA)

Does omega-3 really work for the heart?

The three large randomized trials VITAL, STRENGTH and ASCEND each missed their primary endpoint. Neither in the general population nor in people with diabetes nor in statin-treated high-risk patients could a reduction in major cardiovascular events be shown. The lowering of elevated triglycerides remains well supported.

What did VITAL show about heart attacks?

As a secondary finding, VITAL reported a hazard ratio of 0.72 for total heart attacks. However, this finding comes from a secondary analysis, while the prespecified primary endpoint was missed, with a hazard ratio of 0.92 and a p-value of 0.24. As stand-alone proof of effect, it is not robust.

Does omega-3 make sense after a heart attack?

On March 29, 2019, the EMA confirmed that omega-3 acid ethyl ester medicines at 1 g daily are not effective in preventing further heart problems after a heart attack. This indication was removed. Only the approval for lowering elevated triglycerides remained. Over-the-counter dietary supplements are not directly affected by this decision.

Can omega-3 trigger atrial fibrillation?

A meta-analysis of 35 randomized trials with 114,592 participants found new-onset atrial fibrillation increased in only one single constellation: in people at high cardiovascular risk and at doses above 1,500 mg daily, with an odds ratio of 1.43 and an absolute increase of 0.8 percentage points. All other groups were unremarkable.

What side effects does omega-3 have?

In the high-dose STRENGTH trial, gastrointestinal complaints occurred in 24.7 percent versus 14.7 percent with the comparator oil, meaning about ten percentage points more often. In addition, there is the atrial fibrillation signal in high-risk patients at high doses. Low-quality oils can oxidize; if you take blood thinners, consult a physician.

Which doses were studied in the trials?

VITAL and ASCEND each tested 1 g of marine omega-3 daily against placebo and olive oil, respectively. STRENGTH tested 4 g of omega-3 carboxylic acid daily against corn oil. The meta-analysis on atrial fibrillation included studies from 500 mg of EPA plus DHA daily. No usage recommendation follows from this.

The podcast episode (in German)

Episode 42

Omega-3: the fatty acids for a long life, fact-checked

The podcast by Paul Höser (Episode 42) · with Paul & Paula. The whole scientific detective story: from the observations of the Inuit through the years of null studies to the comeback with REDUCE-IT (Bhatt, NEJM 2019) and VITAL (Manson, NEJM 2019) – and the first randomized anti-aging evidence ever: in the DO-HEALTH study (Bischoff-Ferrari, Nature Aging 2025), 1 g of omega-3 daily slowed the epigenetic clocks. Plus the omega-3 index (target 8–11 %), EPA vs. DHA, quality (TOTOX, algae oil) and an honest look at the atrial fibrillation debate. Information only – not medical advice, no dosage or usage recommendation.

Listen on Spotify

Related

Sources

Open in the database – with search, filters and comparison (German app)

Information only, not medical advice and no usage or dosage recommendation. Prescription and unapproved drugs belong in the hands of a physician. Last updated: 2026-09-13.