Omega-3 fatty acids are among the most extensively researched nutrients in nutritional science — with robust evidence for cardiovascular health, brain function, joint support and beyond. Yet most UK adults consume far below recommended levels. Here’s everything you need to know.
Types of Omega-3
Not all omega-3 fatty acids are equal. ALA (alpha-linolenic acid) — the plant-based omega-3 found in flaxseed, chia seeds, walnuts and rapeseed oil. It’s “essential” (the body can’t make it) but must be converted to EPA and DHA for most biological activity. This conversion is very inefficient — typically 5–10% for EPA and under 1% for DHA. EPA (eicosapentaenoic acid) — the primary anti-inflammatory omega-3. Found in oily fish and algae. Produces anti-inflammatory resolvins and protectins that actively resolve inflammation. DHA (docosahexaenoic acid) — the structural omega-3. Makes up ~60% of the brain’s fatty acid content and is the predominant omega-3 in the retina, heart and sperm. Found in oily fish and algae. Most human studies showing cardiovascular, cognitive and other benefits have used EPA+DHA — not ALA.
Evidence-Based Benefits
Cardiovascular health: EPA+DHA reduce triglycerides significantly (by 20–30% at 2–4g/day), reduce inflammation, modestly lower blood pressure, and may reduce arrhythmia risk. Brain and mental health: DHA is essential for normal brain structure and function at all ages. EPA appears to have antidepressant properties — a 2016 meta-analysis found EPA supplementation (at a ratio of at least 60% EPA) had significant antidepressant effects. Dry eye disease: omega-3s improve meibomian gland function and tear film stability, significantly reducing dry eye symptoms. Pregnancy: DHA is critical for baby’s brain and eye development, particularly in the third trimester. Joint inflammation: omega-3s reduce morning stiffness and tenderness in rheumatoid arthritis — with effect sizes comparable to low-dose NSAIDs in some trials.
Food Sources
The NHS recommends at least 2 portions of fish per week, one of which should be oily. Oily fish options: mackerel (highest), herring, sardines, pilchards, fresh tuna, salmon, trout. 100g of mackerel provides approximately 2.2g EPA+DHA — effectively the whole recommended daily intake in one serving. Vegetarians and vegans: algae-based omega-3 supplements (the fish get their omega-3 from algae) provide the EPA and DHA directly without any fish involvement.
Choosing a Supplement
Look for the combined EPA+DHA content (not just “fish oil XXXmg” — the oil content may be largely other fats). Aim for 500–1000mg EPA+DHA daily for general health. The triglyceride form is better absorbed than the ethyl ester form. Enteric coating reduces fish-breath side effects.
Browse omega-3 supplements in our Everyday Vitamins range at Huncoat Pharmacy. Related: Everyday Supplements Guide.