Omega-3: what '2,000 mg fish oil' really means

The headline number on omega-3 capsules is usually the fish oil, not the omega-3. Here's how to find the EPA and DHA, how much matters, and what the approved claims are.

By Carol Standing · Published 4 November 2026 · 2 min read

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"High strength 2,000 mg!" sounds like a lot of omega-3. Usually it isn't, because the headline number is the fish oil, not the omega-3.

The numbers that matter: EPA and DHA

Fish oil is a mix of fats. The ones with approved health claims are two omega-3 fats: EPA and DHA. Turn the pack over and find the amount of EPA and DHA per daily serving, then add them together. That's your real dose.

Two products can both say "2,000 mg fish oil" and contain very different amounts of EPA and DHA.

Also check the serving size. "2,000 mg" is sometimes per two or three capsules.

What omega-3 can honestly claim

Under UK rules, approved claims include:

EPA and DHA contribute to the normal function of the heart. This applies with a daily intake of 250 mg of EPA plus DHA.
DHA contributes to the maintenance of normal brain function and normal vision. This applies with a daily intake of 250 mg of DHA.

Claims that omega-3 "reduces inflammation", "helps joints", "eases menopause" or "aids weight loss" are not approved claims for a supplement.

What the research says

The US National Institutes of Health summarises the evidence as mixed: eating fish is associated with heart benefits, but trials of supplements in the general population have had mixed results. If you eat oily fish regularly (for example salmon, mackerel or sardines), you may not need a supplement at all.

Safety

Omega-3 supplements are generally well tolerated. Fishy burps are the most common complaint. If you take blood-thinning medicines, speak to your doctor first. People who are pregnant should avoid fish liver oils, because they contain vitamin A.

Our picks

Best for: People who rarely eat oily fish

Fish oil capsules with EPA and DHA listed per serving

Choose one that clearly states the EPA and DHA in mg per daily serving. That's the part you're paying for.

Worth knowing: Speak to your doctor first if you take blood thinners.

See options on Amazon

Best for: Vegetarians and vegans

Algae-based omega-3 (vegan)

Fish get their omega-3 from algae. Algal oil supplies DHA (and often EPA) without fish.

See options on Amazon

The short version

Ignore the "fish oil" headline. Add up EPA + DHA per daily serving.
250 mg of EPA plus DHA a day is the amount the approved heart claim is based on.
Oily fish once or twice a week may be all you need.

Common questions

How much EPA and DHA do I need?

There's no official UK supplement dose. The approved heart claim applies with a daily intake of 250 mg of EPA plus DHA, which works out at roughly one or two portions of oily fish a week (amounts vary by fish), or a standard supplement.

Is a 'Which? Best Buy' label proof a supplement works?

No. Consumer test awards usually rate things like whether the label is accurate and the price per dose. They don't show that a supplement will improve your health.

Is it better to eat oily fish?

Where possible, yes. Oily fish also provides protein, vitamin D and other nutrients. Supplements are an alternative if you don't eat fish.

This article is general information, not medical advice. Speak to a doctor, pharmacist or other qualified clinician about your own health, especially before starting a supplement or if symptoms are new, severe or worrying.

Got a question about this, or a claim you want checked? Ask us.

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