Omega-3 Guide: EPA, DHA and How Much You Actually Need

Omega-3 is one of the most-searched supplement terms in the UK, and also one of the most confusing. Labels quote "1,000 mg fish oil" in large print and the numbers that actually matter in small print. Plant sources are described as if they were interchangeable with oily fish. And advice ranges from "everyone needs it" to "just eat salmon". This guide cuts through it: what EPA and DHA are, how much the evidence supports, how to read a label, and who might consider a supplement.

What are omega-3 fats?

Omega-3s are a family of polyunsaturated fats. Three matter most:

• ALA (alpha-linolenic acid) – found in plant foods such as flaxseed, chia seeds, walnuts and rapeseed oil.
• EPA (eicosapentaenoic acid) – found mainly in oily fish and fish oil.
• DHA (docosahexaenoic acid) – also found mainly in oily fish, fish oil and algae.

Your body can convert a small amount of ALA into EPA and DHA, but the conversion rate is low. That is why most of the research, and the authorised health claims, focus on EPA and DHA themselves.

What EPA and DHA do

In Great Britain, the following health claims are authorised for EPA and DHA:

• EPA and DHA contribute to the normal function of the heart. The beneficial effect is obtained with a daily intake of 250 mg of EPA and DHA.
• DHA contributes to maintenance of normal brain function. The beneficial effect is obtained with a daily intake of 250 mg of DHA.
• DHA contributes to the maintenance of normal vision. The beneficial effect is obtained with a daily intake of 250 mg of DHA.

You will see many other claims online about joints, skin, mood and training recovery. Some are areas of active research, but they are not authorised claims, so treat bold promises with caution.

How much do you need?

The NHS recommends that adults eat at least two portions of fish a week, one of which should be oily (a portion is about 140 g). One portion of salmon or mackerel can provide well over 1 g of EPA and DHA, so if you eat oily fish every week you are probably in good shape.

The reality is that many people in the UK do not. Survey data shows average oily fish consumption is well below the recommendation, especially among younger adults. If that sounds like you, the first step is to add one oily fish meal a week. If fish is not part of your diet, a supplement is a practical alternative.

Good food sources of EPA and DHA

Food (140 g portion)	Approx. EPA + DHA
Mackerel	2.5–3.5 g
Salmon (farmed)	2.0–3.0 g
Sardines (tinned)	1.5–2.0 g
Trout	1.0–1.5 g
Tuna (tinned)	0.2–0.4 g

Values are approximate and vary by species, season and processing. Note that tinned tuna is not counted as an oily fish in UK advice because canning reduces its omega-3 content.

How to read an omega-3 label

This is where most people get caught out. A capsule labelled "1,000 mg fish oil" does not contain 1,000 mg of omega-3. Standard fish oil is often only around 30% EPA and DHA, so that capsule might provide 300 mg in total. When comparing products, look for:

1. The EPA and DHA amounts per daily serving, not the total oil weight.
2. How many capsules make up a serving. A high figure per serving can mean two or three capsules.
3. The form and source – fish oil, krill oil or algal oil (a plant-based option for vegetarians and vegans).
4. Quality testing for purity, and an antioxidant such as vitamin E. Vitamin E contributes to the protection of cells from oxidative stress.

For anyone who rarely eats oily fish, a concentrated fish oil makes reaching the 250 mg reference intake simple. Our Omega 3 softgels provide 700 mg EPA and 500 mg DHA per daily serving, comfortably above the levels used in the authorised claims.

Omega-3 for active people

Athletes are often told to "take fish oil for recovery". The research on omega-3 and exercise is interesting, but results are mixed and there is no authorised claim linking omega-3 to recovery or performance. The honest summary is this: if you train hard, your heart, brain and eyes still benefit from adequate EPA and DHA, just like everyone else's. Recovery is driven mainly by sleep, total energy intake, protein and sensible programming.

Who should be careful?

• People taking blood-thinning medication should speak to their GP or pharmacist before taking high-dose fish oil.
• Pregnant women should avoid cod liver oil and other supplements containing vitamin A (retinol), and should follow NHS advice on fish intake.
• Anyone with a fish allergy should choose an algal-based product and check the label carefully.

Practical tips

• Take fish oil with a meal containing some fat – many people find this also reduces "fishy burps".
• Store capsules away from heat and light, and keep to the best-before date.
• Pair with vitamin D in winter. The NHS advises everyone to consider 10 µg of vitamin D a day from October to March.

Products mentioned in this article

FAQs

How much omega-3 should I take a day?

The authorised claims for heart, brain and vision are based on 250 mg of EPA and DHA (or 250 mg of DHA) a day. Eating two portions of fish a week, one oily, will provide this for most people.

Is fish oil the same as omega-3?

Not exactly. Fish oil contains omega-3 (EPA and DHA) along with other fats. Always check the EPA and DHA content per serving rather than the total amount of oil.

Can vegans get EPA and DHA?

Yes. Algal oil supplements provide EPA and DHA directly from algae, which is where fish get them in the first place.

Are flaxseed and chia seeds enough?

They are good sources of ALA, but the body converts only a small amount of ALA into EPA and DHA. They are healthy foods, but not a like-for-like replacement for oily fish.

When is the best time to take omega-3?

Any time of day is fine. Taking it with a meal is usually the most comfortable option.

Food supplements should not be used as a substitute for a varied, balanced diet and a healthy lifestyle.