Omega 3 - Atherosclerosis - Cardiovascular Prevention

There are 3 omega-3s!
Alpha-linolenic acid or ALA is the only essential omega-3. It is the plant form and is transformed in the body into EPA: eicosapentaenoic acid and docosahexaenoic acid (DHA).
Dietary omega-3s have a protective effect

Data show that a diet rich in omega-3 is beneficial to heart health. The mechanisms are well known: omega-3s reduce inflammation, oxidation of LDL cholesterol and the growth of atherosclerotic plaque, improve the function of blood vessel walls and have a small effect on blood platelets, rather like aspirin.
We also know that Japanese people and devotees of the Mediterranean diet, whose omega-3 intake is higher than that of other populations, are less affected by cardiovascular disease;
But we don't know precisely what part omega-3s play in this reduction in risk, or at what doses.
Could there be other protective factors in these types of diet, such as very low meat consumption, or the fact that people who often eat fish also lead healthier lifestyles? All these questions remain unanswered for the time being.

Can taking omega-3 supplements help keep the heart healthy?

To date, there are no scientific arguments formally demonstrating that taking omega-3 dietary supplements is beneficial for people with no cardiovascular problems.

They lower triglycerides.

Omega-3s reduce triglyceride levels, a type of lipid which, in excess, can contribute to the development of artery disease. However, elevated triglyceride levels expose the body to the risk of acute pancreatitis, and only increase cardiovascular risk if HDL cholesterol levels are reduced at the same time.
Since alcohol remains the major cause of hypertriglyceridemia, it is better to reduce alcohol consumption rather than rely on omega-3 supplementation.

Are supplements recommended for high blood pressure?

They do indeed lower blood pressure, but so minimally that there are no cardiovascular benefits.

They are of interest in cases of high risk factors or a history of cardiovascular events.

Although the results of studies and meta-analyses are often discordant, because they use different forms and dosages of omega-3s, those of the REDUCE-IT study, involving the intake of EPA (Eicosapentaenoic Acid) alone, highly purified and in high doses (2 times 2 grams per day) have changed the game. More than 8,000 people took part, 30% of whom had diabetes and at least one other cardiovascular risk factor, and 70% with established cardiovascular disease, such as a history of stroke or myocardial infarction. All were on statins, with LDL cholesterol levels at the desired target, but with high triglyceride levels. Half of the participants were taking EPA, the other half a placebo. After 5 years' follow-up, there was a 25% reduction in serious or fatal cardiovascular events in the treated group compared with the placebo group, and even a 30% reduction in those who had already had a heart attack, and a 36% reduction if it was a recent event (acute coronary syndrome).

Other studies have confirmed the protective effect of EPA alone and at high doses in high-risk individuals, but none when coupled with DHA (Docosahexaenoic Acid), as if this combination cancelled out the benefits of EPA.

It should be noted that the drug studied in the REDUCE-IT study, although it has been granted marketing authorization in Europe, is not yet marketed in France, nor is its reimbursement guaranteed.

In the meantime, can dietary supplements be an alternative for these patients? In practice, no, because their EPA dosage - between 180 mg and 420 mg per capsule - is much lower than that which has been shown to be effective (4 g/day): you'd have to take between ten and more than 20 a day to reach your target! What's more, they also contain DHA, even though the combination of the two does not work, and the degree of purification is highly variable.

They can have side effects

Especially digestive disorders such as constipation, diarrhea, abdominal pain, heartburn, nausea or vomiting.



In addition, a Chinese study published in 2024, involving over 400,000 people aged 40 to 69, followed for a dozen years and a third of whom reported regularly taking omega-3 dietary supplements derived from fish oil, showed a slight excess risk of arrhythmia: a heart rhythm disorder and stroke; caution as we don't even know the type of food supplements, nor their origin, nor their dosage.

They are sometimes contraindicated.

The risk of Atrial Fibrillation (irregular heartbeat) is well established, and is clearly found with high doses; so don't supplement if you have an arrhythmia, or if you're on anticoagulant or antiplatelet therapy.

What do we need? ANSES recommendations:

ANSES (Agence Nationale de Sécurité de l'Alimentation) recommends a daily intake of 500 mg of omega-3 combining EPA and DHA, and around 2 g of ALA.
(No, we're not going back to our great-grandmothers' cod-liver oil, which provided ... vitamin D.) This can be achieved by eating fish twice a week, including oily fish (mackerel, sardines, herring, salmon...), and by consuming daily plant sources of ALA: walnuts; linseed, walnut, rapeseed or wheat germ oils; or flaxseed.

In summary: Are omega-3s good for the heart?

YES, but :
It depends on the patient, the molecule and the dose:
In secondary prevention, with EPA exclusively and at a dose of 4 g /day.
In all other cases, this is highly doubtful and diet is insufficient.
In France, we're waiting for this treatment to be marketed...
But eat fish!!!

Reference

Gaba P, Bhatt DL, Steg PG, et al, on behalf of the REDUCE-IT Investigators.
Prevention of Cardiovascular Events and Mortality With Icosapent Ethyl in Patients With Prior Myocardial Infarction. J Am Coll Cardiol 2022;79:1660-71.