When you think of omega-3s, what comes to mind?
Oily fish, fish oil capsules, heart health? Probably. But behind this name lie different fats, with characteristics worth knowing about.
Because a walnut, a serving of mackerel, and a supplement can all contain omega-3s without necessarily providing the same things.
A family of fats to get to know
Omega-3s are polyunsaturated fatty acids: their structure contains multiple double bonds. Saturated fats have none, while monounsaturated ones, like the oleic acid in olive oil, have one.
The name “omega-3” indicates the position of the first double bond, counting from one end of the molecule. In omega-6s, that position is different.
It may seem like a chemistry detail, but this structure contributes to their properties. Omega-3s are part of cell membranes and participate in signaling processes. DHA, in particular, is highly prevalent in the brain and retina.
ALA, EPA, and DHA
The three omega-3s discussed most often are ALA, EPA, and DHA.
ALA, or alpha-linolenic acid, is found primarily in plant-based foods such as walnuts, flaxseeds, and chia seeds.
EPA, or eicosapentaenoic acid, and DHA, or docosahexaenoic acid, are found in fatty fish and certain microalgae oils. Sardines, mackerel, and salmon are examples of dietary sources.
These are not just different names for the same nutrient. And knowing this difference helps to better understand what we eat.
Why they are called essential
“Essential” has a precise meaning: it refers to a substance we must obtain from our diet because the body cannot produce it.
Among the omega-3s, it is ALA that is essential in the strict sense. Our body can convert it into EPA and DHA, but it does so in limited quantities, especially for DHA.
This is why sources of ALA and those of EPA and DHA are not automatically interchangeable. And this is why “essential” does not mean that everyone needs to take a supplement.
Seven ideas to rethink
Many claims circulate regarding omega-3s. Some start from a correct fact but arrive at a conclusion that is too simple.
Walnuts completely replace fish
Walnuts provide ALA; fatty fish provides EPA and DHA. They are different foods that can coexist in a diet. However, the limited conversion of ALA prevents them from being considered equivalent.
Omega-3s are only found in fish
There are also microalgae oils that provide DHA and, in some formulations, EPA. Those looking for a plant-based source can therefore find alternatives: what matters is reading which omega-3s the product contains.
A thousand milligrams of fish oil is a thousand milligrams of omega-3s
The weight of the oil does not coincide with the EPA and DHA content. For example, 1,000 mg of oil might contain 180 mg of EPA and 120 mg of DHA: a total of 300 mg. On the label, what counts is the content in the daily dose.
The more I take, the better
A higher dose does not guarantee a greater benefit. Some large high-dose studies have observed an increase in atrial fibrillation, an alteration of the heart rhythm. Therapeutic doses require medical evaluation.
Any supplement prevents heart attacks and strokes
In the VITAL trial, among 25,871 participants with no cardiovascular disease at the start, a daily capsule containing 460 mg of EPA and 380 mg of DHA did not significantly reduce the primary outcome of major cardiovascular events. Favorable signals emerged for some secondary outcomes, such as heart attack, but not universal protection.
Omega-6s are bad and should be eliminated
Omega-6s also include an essential fatty acid. EFSA has not established an ideal numerical omega-6/omega-3 ratio to strive for. Overall diet quality deserves more attention than a proportion presented as perfect.
Omega-3s make you younger
A 2025 study observed small effects on some indicators of biological aging. It is an interesting result, but before turning it into a promise, one must understand what was measured.
What about the benefits for the heart?
Are there intervention studies that have shown concrete benefits?
One of the most important is REDUCE-IT, published in 2019 in the New England Journal of Medicine. It involved 8,179 people at high cardiovascular risk, with high triglycerides despite statin therapy.
Participants received either a placebo or 4 g per day of icosapent ethyl, a drug derived from EPA. After a median period of 4.9 years, the primary outcome, which included heart attack, stroke, and other cardiovascular events, had occurred in 17.2% of the treated group and 22.0% of the placebo group.
The absolute difference was 4.8 percentage points. An important result, obtained however with a specific treatment, in selected people already under clinical supervision. In the same study, hospitalizations for atrial fibrillation or flutter were more frequent.
The STRENGTH trial, published in 2020 in JAMA, involved 13,078 patients and studied a different formulation of EPA and DHA at 4 g per day, without significantly reducing cardiovascular events.
This was not a direct comparison between the two treatments. However, these results remind us that formulation, dose, and the people studied matter. The benefit of a drug cannot be automatically attributed to any fish oil supplement.
The latest research on aging
In 2025, a study published in Nature Aging reported an analysis of 777 participants from the DO-HEALTH trial, followed for three years.
Researchers evaluated omega-3s, vitamin D, and physical activity using various “epigenetic clocks”: indicators based on DNA modifications used to estimate aspects of biological aging.
With 1 g per day of omega-3s, a small slowing of some indicators emerged. For some measures, the reported effects corresponded to approximately 2.9–3.8 months over the course of three years.
However, this was a post-hoc analysis of the trial, on a subgroup and on biological markers. It does not prove that omega-3s make you younger, prevent all age-related diseases, or extend life. It offers an interesting direction for research.
Where to start in daily life
With a varied diet that includes sources of ALA and, when possible, EPA and DHA.
For adults, EFSA indicates an adequate intake of 250 mg per day of total EPA and DHA. This is a nutritional reference, not a dose for treating a disease.
A supplement can help complete an insufficient intake, but it does not replace a varied diet. Those taking medications, especially anticoagulants, should coordinate their use with their doctor.
At ALUNEMA, we want to help you better understand what you choose for your well-being. Omega-3s also deserve to be discussed clearly, leaving room for both documented benefits and questions that remain open.
The most informed choice begins with understanding what we are taking, in what quantity, and for what reason.
Scientific note: NIH Office of Dietary Supplements, Omega-3 Fatty Acids — Health Professional Fact Sheet and Consumer Fact Sheet. EFSA, Dietary Reference Values for fats, 2010. Bhatt D. L. et al., Cardiovascular Risk Reduction with Icosapent Ethyl for Hypertriglyceridemia, NEJM, 2019. Nicholls S. J. et al., STRENGTH Randomized Clinical Trial, JAMA, 2020. Manson J. E. et al., Marine n-3 Fatty Acids and Prevention of Cardiovascular Disease and Cancer, NEJM, 2019. Bischoff-Ferrari H. A. et al., DO-HEALTH and epigenetic aging clocks, Nature Aging, 2025.
This article is for informational purposes only. The results of the studies described do not demonstrate therapeutic effects of ALUNEMA products and do not replace medical evaluation.