What Is Omega-3?
Omega-3 refers to a family of polyunsaturated fats, the three most relevant being ALA (found in plant sources like flaxseed and walnuts), and EPA and DHA (found almost exclusively in oily fish and algae). The body can convert a small amount of ALA into EPA and DHA, but the conversion rate is low — which is why fish or algae-based sources matter more for reaching meaningful levels.
Why Your Body Needs It
EFSA has authorised more health claims for EPA and DHA than for almost any other supplement ingredient, each tied to a specific minimum daily intake:
- 250mg EPA + DHA/day — contributes to the normal function of the heart
- 250mg DHA/day — contributes to the maintenance of normal brain function
- 250mg DHA/day — contributes to the maintenance of normal vision
- 2g EPA + DHA/day — contributes to the maintenance of normal blood triglyceride levels
- 3g EPA + DHA/day — contributes to the maintenance of normal blood pressure
- DHA intake by the mother contributes to the normal development of the eye and brain in the foetus and breastfed infants
Note the dose thresholds: a standard 250–500mg fish oil capsule covers the heart, brain, and vision claims, but not the higher-dose triglyceride or blood pressure claims — that’s worth knowing before assuming a bottle’s marketing applies to its actual dose.
Signs You May Not Be Getting Enough
Omega-3 “deficiency” in the clinical sense is rare in the UK/EU, but chronically low intake is common — the average UK diet contains only a fraction of recommended oily fish intake. Signs sometimes associated with low intake include:
- Dry skin or brittle nails
- Difficulty concentrating
- Joint stiffness
- Low mood
These are non-specific and can have many other causes, so they’re a prompt to review your diet rather than a diagnosis.
Who Should Pay Attention
- People who eat oily fish less than twice a week (the majority of UK adults, per national dietary surveys)
- Vegans and vegetarians, since EPA/DHA (as opposed to plant-based ALA) come almost exclusively from fish and algae
- People focused on cardiovascular or cognitive health as a long-term priority
- Pregnant and breastfeeding women, given DHA’s role in foetal and infant brain/eye development (always confirm dosage with a midwife or GP)
Food Sources
- Salmon, mackerel, sardines, anchovies, trout — the richest sources of EPA/DHA
- Flaxseed, chia seeds, walnuts — good sources of plant-based ALA (lower conversion efficiency)
- Algae oil — the only direct non-fish source of EPA/DHA, relevant for vegans
UK dietary guidelines recommend at least two portions of fish a week, one of which should be oily — most adults fall well short of this.
Choosing an Omega-3 Supplement
- Check the EPA + DHA content, not just the total fish oil weight — a 1000mg capsule might only contain 300mg of actual EPA/DHA
- Triglyceride form is generally better absorbed than the cheaper ethyl ester form found in some budget products
- Third-party purity testing matters for fish oil, given concerns about heavy metals and oxidation in lower-quality products
- Algae-based options for anyone avoiding fish
Our pick: Solgar Triple Strength Omega-3 — a high-EPA/DHA fish oil formulation.
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This page is for general educational purposes only and is not medical advice. If you’re pregnant, breastfeeding, or on blood-thinning medication, check with a healthcare professional before starting a high-dose fish oil supplement.
Sources & Further Reading
- NHS — Fish and shellfish
- NIH Office of Dietary Supplements — Omega-3 Fatty Acids Fact Sheet
- EFSA — Approved omega-3 health claims
- Linus Pauling Institute — Essential Fatty Acids
- Examine.com — Fish Oil
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