Most of us know omega‑3s are “good for you” — but what do they actually do, especially for your brain, heart, and long-term health?
Recent studies suggest that omega‑3s — especially EPA and DHA — may support memory, mood, blood pressure, behaviour, and even biological ageing.
They’re not a cure-all, but they may play a helpful role — particularly when consumed regularly over time.
Here’s what the strongest and most credible research shows.
A 2023 review pooled data from 48 long-term studies, involving over 100,000 people.
It found that those with higher intakes of omega‑3s — especially DHA, found in oily fish and algal oil — had around a 20% lower risk of cognitive decline or dementia.
The benefits were even greater in people with the APOE‑ε4 gene, a common risk factor for Alzheimer’s.
In a clinical trial of older adults with coronary artery disease, those taking 3.36 g/day of EPA and DHA for 30 months experienced 2.5 years’ slower cognitive decline compared to those not taking omega‑3s.
That’s a significant effect, especially in people already at risk.
Omega‑3s remain one of the most studied nutrients for cardiovascular health.
A 2021 Cochrane review covering 86 randomised trials confirmed that omega‑3s can help:
Lower blood triglycerides (by 13–33%)
Improve arterial flexibility
Reduce resting heart rate
Several large-scale reviews show that omega‑3s can help reduce blood pressure by around 2–4 mmHg, particularly in people with high blood pressure or heart disease.
Even small reductions like this can make a difference — for example, a 2 mmHg drop in systolic pressure across a population is linked with lower rates of stroke and heart attack.
And this isn’t just based on emerging science — it’s officially recognised. In the UK, there’s an authorised nutritional health claim that EPA and DHA (omega‑3s) contribute to the maintenance of normal blood pressure (at 3 g/day) and normal blood triglyceride levels (at 2 g/day).
A 2024 meta-analysis of randomised trials suggested that omega‑3s may reduce symptoms of anxiety, with the greatest benefit seen at ~2 g/day.
The certainty is low, but the direction of effect is positive.
In the DO‑HEALTH trial, 1 g/day of omega‑3 over 3 years modestly slowed epigenetic ageing — how “old” your cells appear based on DNA markers.
When combined with vitamin D and regular exercise, the effect was even stronger.
1. Aim for two portions of fish per week.
The NHS recommends two portions of fish weekly, with at least one portion of oily fish, such as:
Salmon
Mackerel
Sardines
Herring
Trout
This provides enough EPA and DHA for most people.
2. Don't eat fish? Try algae oil
Algal DHA (from marine algae) is the best plant-based source. Just 250 mg/day is enough to raise blood DHA levels in vegans and vegetarians.
3. Add ALA-rich foods — but don’t rely on them alone
ALA is a plant omega‑3 found in:
Ground flax or chia seeds
Walnuts
Rapeseed oil
It’s healthy — but the body converts only a small amount into EPA and DHA, so it’s not a direct replacement for fish or algal oil.
4. Omega 3 Supplements? Helpful when intake is low
If you don’t eat much fish, or follow a plant-based diet, a daily omega‑3 supplement can help
Omega‑3s aren’t a miracle fix — and they’re not a substitute for the fundamentals: good sleep, regular movement, social connection, and a varied, whole-food diet.
While research shows consistent associations with brain, heart, and behavioural benefits, the effects are often modest — and not everyone will
experience noticeable changes.
In many studies, omega‑3s slightly improve biological markers (like cholesterol or inflammation), but these shifts may not translate into meaningful outcomes for every individual. That’s especially true if other parts of lifestyle remain unchanged.
Still, the low risk and broad range of potential benefits — especially for those with low fish intake — make omega‑3s a worthwhile part of the bigger picture.
A few small, consistent steps — like adding oily fish to your meals, or taking a daily algal oil capsule — could help support long-term brain and heart health as part of a wider healthy lifestyle.
1. Can omega‑3s prevent dementia?
They may help lower the risk, especially if started early. They’re not a cure, but may support long-term brain health.
2. Can they improve memory if I already have symptoms?
Trials in people with Alzheimer’s have shown limited benefit. Starting before symptoms is likely more helpful.
3. Do they help with blood pressure?
Yes, especially at 3 g/day. Effects are small but consistent.
4. Do I need supplements if I eat fish?
Not usually. If you eat oily fish 1–2 times per week, you're probably getting enough.
5. What if I’m vegan or allergic to fish?
Algal oil is the best alternative — it provides DHA without fish.
6. Can omega‑3s affect mood or behaviour?
They may support anxiety relief and reduce aggression, based on growing clinical evidence.
This article is for general information only and is not intended to treat or diagnose medical conditions. If in doubt please check with your GP first.
References:
Wei B‑Z, et al. Am J Clin Nutr. 2023 — 20% lower dementia risk with higher omega‑3 intake
Welty FK. Curr Opin Clin Nutr Metab Care, 2023 — slower brain ageing with 3.36 g/day EPA+DHA
Abdelhamid AS et al. Cochrane Database Syst Rev, 2021 — omega‑3 improves heart health markers
Zhang Y et al. J Am Heart Assoc, 2022 — 2–4 mmHg lower blood pressure
UK Nutrition & Health Claims Register (Claims 4421 & 4405) — EFSA-approved blood pressure and triglyceride claims
Bafkar N et al. Front Psychiatry, 2024 — omega‑3 may reduce anxiety symptoms
Raine A et al. Aggress Violent Behav, 2024 — reduced aggression with omega‑3
Bischoff-Ferrari HA et al. Nature Aging, 2025 — slower epigenetic ageing with omega‑3
García-Maldonado E et al. Clin Nutr ESPEN, 2022 — 250 mg algal DHA raises DHA levels
NHS. Eatwell Guide — oily fish intake recommendations
NIH Office of Dietary Supplements — ALA conversion and safety overview
British Heart Foundation — Omega‑3 & heart health guidance
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